## This Week’s Finds (Week 301)

The first 300 issues of This Week’s Finds were devoted to the beauty of math and physics. Now I want to bite off a bigger chunk of reality. I want to talk about all sorts of things, but especially how scientists can help save the planet. I’ll start by interviewing some scientists with different views on the challenges we face — including some who started out in other fields, because I’m trying to make that transition myself.

By the way: I know “save the planet” sounds pompous. As George Carlin joked: “Save the planet? There’s nothing wrong with the planet. The planet is fine. The people are screwed.” (He actually put it a bit more colorfully.)

But I believe it’s more accurate when he says:

I think, to be fair, the planet probably sees us as a mild threat. Something to be dealt with. And I am sure the planet will defend itself in the manner of a large organism, like a beehive or an ant colony, and muster a defense.

I think we’re annoying the biosphere. I’d like us to become less annoying, both for its sake and our own. I actually considered using the slogan how scientists can help humans be less annoying — but my advertising agency ran a focus group, and they picked how scientists can help save the planet.

Besides interviewing people, I want to talk about where we stand on various issues, and what scientists can do. It’s a very large task, so I’m really hoping lots of you reading this will help out. You can explain stuff, correct mistakes, and point me to good sources of information. With a lot of help from Andrew Stacey, I’m starting a wiki where we can collect these pointers. I’m hoping it will grow into something interesting.

But today I’ll start with a brief overview, just to get things rolling.

In case you haven’t noticed: we’re heading for trouble in a number of ways. Our last two centuries were dominated by rapid technology change and a rapidly soaring population:

The population is still climbing fast, though the percentage increase per year is dropping. Energy consumption per capita is also rising. So, from 1980 to 2007 the world-wide usage of power soared from 10 to 16 terawatts.

96% of this power now comes from fossil fuels. So, we’re putting huge amounts of carbon dioxide into the air: 30 billion metric tons in 2007. So, the carbon dioxide concentration of the atmosphere is rising at a rapid clip: from about 290 parts per million before the industrial revolution, to about 370 in the year 2000, to about 390 now:

As you’d expect, temperatures are rising:

But how much will they go up? The ultimate amount of warming will largely depend on the total amount of carbon dioxide we put into the air. The research branch of the National Academy of Sciences recently put out a report on these issues:

• National Research Council, Climate Stabilization Targets: Emissions, Concentrations, and Impacts over Decades to Millennia, 2010.

Here are their estimates:

You’ll note there’s lots of uncertainty, but a rough rule of thumb is that each doubling of carbon dioxide will raise the temperature around 3 degrees Celsius. Of course people love to argue about these things: you can find reasonable people who’ll give a number anywhere between 1.5 and 4.5 °C, and unreasonable people who say practically anything. We’ll get into this later, I’m sure.

But anyway: if we keep up “business as usual”, it’s easy to imagine us doubling the carbon dioxide sometime this century, so we need to ask: what would a world 3 °C warmer be like?

It doesn’t sound like much… until you realize that the Earth was only about 6 °C colder during the last ice age, and the Antarctic had no ice the last time the Earth was about 4 °C warmer. You also need to bear in mind the shocking suddenness of the current rise in carbon dioxide levels:

You can see several ice ages here — or technically, ‘glacial periods’. Carbon dioxide concentration and temperature go hand in hand, probably due to some feedback mechanisms that make each influence the other. But the scary part is the vertical line on the right where the carbon dioxide shoots up from 290 to 390 parts per million — instantaneously from a geological point of view, and to levels not seen for a long time. Species can adapt to slow climate changes, but we’re trying a radical experiment here.

But what, specifically, could be the effects of a world that’s 3 °C warmer? You can get some idea from the National Research Council report. Here are some of their predictions. I think it’s important to read these, to see that bad things will happen, but the world will not end. Psychologically, it’s easy to avoid taking action if you think there’s no problem — but it’s also easy if you think you’re doomed and there’s no point.

Between their predictions (in boldface) I’ve added a few comments of my own. These comments are not supposed to prove anything. They’re just anecdotal examples of the kind of events the report says we should expect.

For 3 °C of global warming, 9 out of 10 northern hemisphere summers will be “exceptionally warm”: warmer in most land areas than all but about 1 of the summers from 1980 to 2000.

This summer has certainly been exceptionally warm: for example, worldwide, it was the hottest June in recorded history, while July was the second hottest, beat out only by 2003. Temperature records have been falling like dominos. This is a taste of the kind of thing we might see.

Increases of precipitation at high latitudes and drying of the already semi-arid regions are projected with increasing global warming, with seasonal changes in several regions expected to be about 5-10% per degree of warming. However, patterns of precipitation show much larger variability across models than patterns of temperature.

Back home in southern California we’re in our fourth year of drought, which has led to many wildfires.

Large increases in the area burned by wildfire are expected in parts of Australia, western Canada, Eurasia and the United States.

We are already getting some unusually intense fires: for example, the Black Saturday bushfires that ripped through Victoria in February 2007, the massive fires in Greece later that year, and the hundreds of wildfires that broke out in Russia this July.

Extreme precipitation events — that is, days with the top 15% of rainfall — are expected to increase by 3-10% per degree of warming.

The extent to which these events cause floods, and the extent to which these floods cause serious damage, will depend on many complex factors. But today it hard not to think about the floods in Pakistan, which left about 20 million homeless, and ravaged an area equal to that of California.

In many regions the amount of flow in streams and rivers is expected to change by 5-15% per degree of warming, with decreases in some areas and increases in others.

The total number of tropical cyclones should decrease slightly or remain unchanged. Their wind speed is expected to increase by 1-4% per degree of warming.

The annual average sea ice area in the Arctic is expected to decrease by 15% per degree of warming, with more decrease in the summertime.

The area of Arctic ice reached a record low in the summer of 2007, and the fabled Northwest Passage opened up for the first time in recorded history. Then the ice area bounced back. This year it was low again… but what matters more is the overall trend:

Global sea level has risen by about 0.2 meters since 1870. The sea level rise by 2100 is expected to be at least 0.6 meters due to thermal expansion and loss of ice from glaciers and small ice caps. This could be enough to permanently displace as many as 3 million people — and raise the risk of floods for many millions more. Ice loss is also occurring in parts of Greenland and Antarctica, but the effect on sea level in the next century remains uncertain.

Up to 2 degrees of global warming, studies suggest that crop yield gains and adaptation, especially at high latitudes, could balance losses in tropical and other regions. Beyond 2 degrees, studies suggest a rise in food prices.

The first sentence there is the main piece of good news — though not if you’re a poor farmer in central Africa.

Increased carbon dioxide also makes the ocean more acidic and lowers the ability of many organisms to make shells and skeleta. Seashells, coral, and the like are made of aragonite, one of the two crystal forms of calcium carbonate. North polar surface waters will become under-saturated for aragonite if the level of carbon dioxide in the atmosphere rises to 400-450 parts per million. Then aragonite will tend to dissolve, rather than form from seawater. For south polar surface waters, this effect will occur at 500-660 ppm. Tropical surface waters and deep ocean waters are expected to remain supersaturated for aragonite throughout the 20th century, but coral reefs may be negatively impacted.

Coral reefs are also having trouble due to warming oceans. For example, this summer there was a mass dieoff of corals off the coast of Indonesia due to ocean temperatures that were 4 °C higher than average.

Species are moving toward the poles to keep cool: the average shift over many types of terrestrial species has been 6 kilometers per decade. The rate of extinction of species will be enhanced by climate change.

I have a strong fondness for the diversity of animals and plants that grace this planet, so this particularly perturbs me. The report does not venture a guess for how many species may go extinct due to climate change, probably because it’s hard to estimate. However, it states that the extinction rate is now roughly 500 times what it was before humans showed up. The extinction rate is measured extinctions per million years per species. For mammals, it’s shot up from roughly 0.1-0.5 to roughly 50-200. That’s what I call annoying the biosphere!

So, that’s a brief summary of the problems that carbon dioxide emissions may cause. There’s just one more thing I want to say about this now.

Once carbon dioxide is put into the atmosphere, about 50% of it will stay there for decades. About 30% of it will stay there for centuries. And about 20% will stay there for thousands of years:

This particular chart is based on some 1993 calculations by Wigley. Later calculations confirm this idea: the carbon we burn will haunt our skies essentially forever:

• Mason Inman, Carbon is forever, Nature Reports Climate Change, 20 November 2008.

This is why we’re in serious trouble. In the above article, James Hansen puts it this way:

Because of this long CO2 lifetime, we cannot solve the climate problem by slowing down emissions by 20% or 50% or even 80%. It does not matter much whether the CO2 is emitted this year, next year, or several years from now. Instead … we must identify a portion of the fossil fuels that will be left in the ground, or captured upon emission and put back into the ground.

But I think it’s important to be more precise. We can put off global warming by reducing carbon dioxide emissions, and that may be a useful thing to do. But to prevent it, we have to cut our usage of fossil fuels to a very small level long before we’ve used them up.

Theoretically, another option is to quickly deploy new technologies to suck carbon dioxide out of the air, or cool the planet in other ways. But there’s almost no chance such technologies will be practical soon enough to prevent significant global warming. They may become important later on, after we’ve already screwed things up. We may be miserable enough to try them, even though they may carry significant risks of their own.

So now, some tough questions:

If we decide to cut our usage of fossil fuels dramatically and quickly, how can we do it? How should we do it? What’s the least painful way? Or should we just admit that we’re doomed to global warming and learn to live with it, at least until we develop technologies to reverse it?

And a few more questions, just for completeness:

Could this all be just a bad dream — or more precisely, a delusion of some sort? Could it be that everything is actually fine? Or at least not as bad as you’re saying?

I won’t attempt to answer any of these now. We’ll have to keep coming back to them, over and over.

So far I’ve only talked about carbon dioxide emissions. There are lots of other problems we should tackle, too! But presumably many of these are just symptoms of some deeper underlying problem. What is this deeper problem? I’ve been trying to figure that out for years. Is there any way to summarize what’s going on, or it is just a big complicated mess?

Here’s my attempt at a quick summary: the human race makes big decisions based on an economic model that ignores many negative externalities.

A ‘negative externality’ is, very roughly, a way in which my actions impose a cost on you, for which I don’t pay any price.

For example: suppose I live in a high-rise apartment and my toilet breaks. Instead of fixing it, I realize that I can just use a bucket — and throw its contents out the window! Whee! If society has no mechanism for dealing with people like me, I pay no price for doing this. But you, down there, will be very unhappy.

This isn’t just theoretical. Once upon a time in Europe there were few private toilets, and people would shout “gardyloo!” before throwing their waste down to the streets below. In retrospect that seems disgusting, but many of the big problems that afflict us now can be seen as the result of equally disgusting externalities. For example:

Carbon dioxide pollution caused by burning fossil fuels. If the expected costs of global warming and ocean acidification were included in the price of fossil fuels, other sources of energy would more quickly become competitive. This is the idea behind a carbon tax or a ‘cap-and-trade program’ where companies pay for permits to put carbon dioxide into the atmosphere.

Dead zones. Put too much nitrogen and phosophorus in the river, and lots of algae will grow in the ocean near the river’s mouth. When the algae dies and rots, the water runs out of dissolved oxygen, and fish cannot live there. Then we have a ‘dead zone’. Dead zones are expanding and increasing in number. For example, there’s one about 20,000 square kilometers in size near the mouth of the Mississippi River. Hog farming, chicken farming and runoff from fertilized crop lands are largely to blame.

Overfishing. Since there is no ownership of fish, everyone tries to catch as many fish as possible, even though this is depleting fish stocks to the point of near-extinction. There’s evidence that populations of all big predatory ocean fish have dropped 90% since 1950. Populations of cod, bluefish tuna and many other popular fish have plummeted, despite feeble attempts at regulation.

Species extinction due to habitat loss. Since the economic value of intact ecosystems has not been fully reckoned, in many parts of the world there’s little price to pay for destroying them.

Overpopulation. Rising population is a major cause of the stresses on our biosphere, yet it costs less to have your own child than to adopt one. (However, a pilot project in India is offering cash payments to couples who put off having children for two years after marriage.)

One could go on; I haven’t even bothered to mention many well-known forms of air and water pollution. The Acid Rain Program in the United States is an example of how people eliminated an externality: they imposed a cap-and-trade system on sulfur dioxide pollution.

Externalities often arise when we treat some resource as essentially infinite — for example fish, or clean water, or clean air. We thus impose no cost for using it. This is fine at first. But because this resource is free, we use more and more — until it no longer makes sense to act as if we have an infinite amount. As a physicist would say, the approximation breaks down, and we enter a new regime.

This is happening all over the place now. We have reached the point where we need to treat most resources as finite and take this into account in our economic decisions. We can’t afford so many externalities. It is irrational to let them go on.

We can do the things anyone can do. Educate ourselves. Educate our friends. Vote. Conserve energy. Don’t throw buckets of crap out of apartment windows.

But what can we do that maximizes our effectiveness by taking advantage of our special skills?

Starting now, a large portion of This Week’s Finds will be the continuing story of my attempts to answer this question. I want to answer it for myself. I’m not sure what I should do. But since I’m a scientist, I’ll pose the question a bit more broadly, to make it a bit more interesting.

How scientists can help save the planet — that’s what I want to know.

Addendum: In the new This Week’s Finds, you can often find the source for a claim by clicking on the nearest available link. This includes the figures. Four of the graphs in this issue were produced by Robert A. Rohde and more information about them can be found at Global Warming Art.

During the journey we commonly forget its goal. Almost every profession is chosen as a means to an end but continued as an end in itself. Forgetting our objectives is the most frequent act of stupidity. — Friedrich Nietzsche

### 197 Responses to This Week’s Finds (Week 301)

1. Hybrid Moiety says:

I think developments to improve our nuclear technology are the most foolproof way long-term to reduce carbon emission. Reduce waste production, improve safety, and reduce plant cost to par with coal. Cost reduction is important because if plant cost stays at the current level nothing would happen.

Side benefits such as desalination can be important when California runs into water shortage.

• John Baez says:

I find it a bit odd how divergent people’s opinions are when it comes to nuclear power. Over on Climate Progress, I wrote:

It’s interesting how everyone here seems opposed to nuclear power.

James Lovelock wrote:

I find it sad and ironic that the UK, which leads the world in the quality of its Earth and climate scientists, rejects their warnings and advice, and prefers to listen to the Greens. But I am a Green and I entreat my friends in the movement to drop their wrongheaded objection to nuclear energy.

Even if they were right about its dangers, and they are not, its worldwide use as our main source of energy would pose an insignificant threat compared with the dangers of intolerable and lethal heat waves and sea levels rising to drown every coastal city of the world. We have no time to experiment with visionary energy sources; civilisation is in imminent danger and has to use nuclear – the one safe, available, energy source – now or suffer the pain soon to be inflicted by our outraged planet.

James Hansen also thinks we need nuclear power. The Australian writes:

“We should undertake urgent focused research and development programs in next generation nuclear power,” said atmospheric physicist James Hansen, head of NASA’s Goddard Institute for Space Studies and adjunct professor at Columbia University’s Earth Institute in New York.

While renewable energies such as solar and wind were gaining in economic competition with coal-fired plants, Professor Hansen said they wouldn’t be able to provide baseload power for years to come.

Even in Germany, which pushed renewables heavily, they generated only 7 per cent of the nation’s power.

“It’s just too expensive,” said Professor Hansen, an expert in climate modelling, planetary atmospheres and the Earth’s climate.

“Right now, fossil fuels are the cheapest form of energy, except for operating nuclear plants,” he said on the first day of a lecture tour in Australia.

According to Professor Hansen, because the threat of global warming was so serious, nations such as the US, China and even Australia must crank up support for so-called third and fourth generation nuclear systems.

“Current nuclear plants are the second generation. The third generation is ready to build now,” he explained, pointing to conventional light water reactors, which generated heat by the fission of uranium fuel. Two fourth-generation technologies are on the drawing board. Fast reactors use liquid sodium metal as a coolant for the fission of metallic solid fuel, including existing nuclear waste and weapons-grade uranium and plutonium.

Thorium reactors use fluoride salt as the medium for the energy-producing nuclear reaction, so they don’t require production of fuel rods.

Professor Hansen admitted he was a late convert to advanced nuclear power. “But fourth generation solves two of the problems that made me sceptical,” he said.

“One is nuclear waste. It uses over 99 per cent of the fuels, while second and third generations use less than 1 per cent, leaving a waste pile with a half-life of 100,000 years. Fourth generation burns almost all the fuel and waste has a half life of decades.”

No commercial scale fourth-generation plants exist, but seven nations, including Japan, France and China, have expertise or research and development projects. Which will get their first? “That’s an open question,” according to Professor Hansen.”

Stewart Brand also thinks we need it:

Can climate change be slowed and catastrophe avoided? They can to the degree that humanity influences climate dynamics. The primary cause of global climate change is our burning of fossil fuels for energy.

So everything must be done to increase energy efficiency and decarbonize energy production. Kyoto accords, radical conservation in energy transmission and use, wind energy, solar energy, passive solar, hydroelectric energy, biomass, the whole gamut. But add them all up and it’s still only a fraction of enough. Massive carbon “sequestration” (extraction) from the atmosphere, perhaps via biotech, is a widely held hope, but it’s just a hope. The only technology ready to fill the gap and stop the carbon dioxide loading of the atmosphere is nuclear power.

Nuclear certainly has problems—accidents, waste storage, high construction costs, and the possible use of its fuel in weapons. It also has advantages besides the overwhelming one of being atmospherically clean. The industry is mature, with a half-century of experience and ever improved engineering behind it. Problematic early reactors like the ones at Three Mile Island and Chernobyl can be supplanted by new, smaller-scale, meltdown-proof reactors like the ones that use the pebble-bed design. Nuclear power plants are very high yield, with low-cost fuel. Finally, they offer the best avenue to a “hydrogen economy,” combining high energy and high heat in one place for optimal hydrogen generation.

The storage of radioactive waste is a surmountable problem. Many reactors now have fields of dry-storage casks nearby. Those casks are transportable. It would be prudent to move them into well-guarded centralized locations. Many nations address the waste storage problem by reprocessing their spent fuel, but that has the side effect of producing material that can be used in weapons. One solution would be a global supplier of reactor fuel, which takes back spent fuel from customers around the world for reprocessing. That’s the kind of idea that can go from “Impractical!” to “Necessary!” in a season, depending on world events.

The environmental movement has a quasi-religious aversion to nuclear energy. The few prominent environmentalists who have spoken out in its favor—Gaia theorist James Lovelock, Greenpeace cofounder Patrick Moore, Friend of the Earth Hugh Montefiore—have been privately anathematized by other environmentalists. Public excoriation, however, would invite public debate, which so far has not been welcome.

I’m not sure what I think, but these guys aren’t dumb, and the world could be running out of options.

I was roundly scolded for my comment. The gist seemed to be something like:

1) Nuclear power is burdened by so many regulations that it takes a long time to get permits to build nuclear power plants, at least in the US — too long for them to save us from serious global warming.

2) Nuclear power advocates are asking for big government subsidies. Solar power is now cheaper than nuclear.

But I want to examine both sides of this argument more carefully.

• Roger Witte says:

There are interesting (?) interactions between nuclear power and climate change that are often neglected. For example most nuclear plants are currently sited on the land near the coast, but they are not designed to operate under water. What happens to the containment of radiation when the sea levels rise?

• bane says:

Here’s my 2 pence on the nuclear: I think it’s very likely to be essential, but even if it isn’t I think work ought to start now. The basic reason is that I’m (partly) an engineer, and two of the important things to keep in mind are

1. research prototypes of anything often work, but are not robust and often have significant unexplored regions of the “operating conditions space”.

2. completion of a design and then going into a hyper-rapid build-out is the surest way to create a big problem. (One of the things that worry me is that a lot of the most vocal nuclear supporters on the internet are software architects/web designers who don’t seem to appreciate that, in the event of a “bug” in a nuclear reactor, it’s more than just removing the script and restarting the server that’s needed.)

The blue line in this graph shows current world nuclear power capacity, so if you mentally differentiate it you can glimpse that production of new reactors has been very low over the past 15-20 years. As such there are relatively few designers, contractors, overseers, etc, with in the field experience of all the practical issues. So my view is that all the countries of need to start relatively slow design and building programs so that, collectively, we can make and discover most of the mistakes before, in 15-30 years time, we may well need to initiate a more intensive building proven designs with q wider pool of experienced workers.

[This isn’t just my flight of fancy. As an example, there has been the converse of Roger Witte’s scenario above actually happen: water cooled reactors in France have needed emergency shutdown when the rivers providing cooling water almost ran dry during a hot summer. So nuclear designers now know to be very conservative about cooling water availability assumptions when choosing reactor sites. But what other mistakes are lying latent in current designs that will only be found by deployment?]

• Joe Kaplinsky says:

The nuclear energy debate is a mess. Opponents are right that it’s burdened by so many regulations that it will take a long time to make a difference. But that is largely because … opponents never stop demanding more regulations. Trying to figure out costs and subsidies is an even worse swamp. All forms of energy are subsidised. How do you account for the cost of disposing nuclear waste? If you want to keep every radioactive atom away from human contact for a million years then you can spend billions just trying to study the geology of a waste repository, let alone building it. Meanwhile, ignore the previously buried uranium atoms pouring out of the chimney of the coal power station. Alternatively that waste could be reprocessed and largely turned into new fuel – unless you worry that will lead weapons proliferation.

Costs on the various dimensions of safety can be inflated indefinitely, it’s not a straightforward question of accountancy. I believe that nuclear energy can be done safely for reasonable cost. (I wouldn’t try to estimate costs by better than a factor of two, especially thinking on a decadal scale. If an energy source is ten times too expensive, it needs more research. If it is a factor two too expensive and it has potential to produce a lot of clean energy I would be inclined to support it with subsidy – now I would say that means nuclear, quite a bit of wind and a small but growing amount of solar.)

There’s lots of information available from a nuclear industry association here. It doesn’t pretend to be anything other than pro-nuclear, but I think it is well informed and basically honest.

On bane’s point about lack of trained engineers, data shows that new nuclear energy is being built mainly in the east – in China, India, South Korea, Japan and Russia. That may distort the European / American perspective a bit. Also France created a nuclear energy industry very quickly from a low base. But I do agree given the scale of energy demand, time is a factor. Fifteen years ago I would have put a lot more emphasis on nuclear rather than wind. Since then, wind has turned into a real, if fledgling industry. A lot of resources have gone into investment, training and research. I think that where we are, it is worth investing in both (as well as solar, geothermal and long term fusion research) as nuclear has a variety of advantages and complementary properties.

• Hybrid Moiety says:

I mostly see this as a practice of fighting the previous battle. It is true the light water reactor design has a lot of practical constraints, such as excessive nuclear waste production, and high plant cost.

Wind and solar can’t address the base load. By logic of elimination you are left with only nuclear.

Not a lot of people are familiar with the advantages of the molten salt reactor design. In a molten salt reactor the active fuel is circulated at room pressure. The reactor produces less nuclear waste. It can use nitrogen gas instead of water for cooling. Its construction cost should be lower since it does not need a huge containment dome.

The only catch is that its development is unfunded and we only had data from a test plant that was shutdown in 1969. It faces a sort of “Betamax” problem, but these things can be overcome if we recognize our survival is at stake.

• Giampiero Campa says:

Michael Dittmar from CERN has written a very interesting and detailed 4-parts report regarding status and future perspectives for nuclear energy:

The gist is that, using conventional reactors, we will run out of uranium even before we run out of oil. We don’t really know yet whether 4th-generation reactors are feasible, and most likely fusion is NOT feasible. He specifically leaves the door open for thorium reactors though, while i imagine that decades of research might still be needed for them.

But i encourage you to have a look at the reports themselves because they are really well written and interesting.

My opinion on solar energy is that perhaps time has come for the governments to pull the plug on financing it. Apart from other reasons, solar cells have a limited life and tend to break down after 20-some years, thus requiring constant re-installation on very very large surfaces. When i did try to add everything up, it did not look feasible to me to have 15-20TW coming out from solar power.

On the other hand, eolic, while requiring a lot of up-front investments (and batteries to store energy), does look feasible. Denmark has 20% of its energy coming from wind right NOW, and other countries range from 8 to 14%. So it looks just a matter of installing (many) more turbines. On top of that, this is a technology that is still evolving fast, so we might still expect several efficiency improvements.

• quakeyjase says:

Nuclear is statistically fairly safe but if you happen to be on the wrong side of the statistics, that isn’t much comfort as the results are not very pleasant (eg. Fukushima). Fusion would be nice, but we probably don’t have time to get it working: my hunch is that tokamaks are very good at throwing plasma round and round without any actual energy generation. (But I have a friend who is working on it anyway). As luck would have it we have a fully operational fusion reactor located at a safe distance whose power is available almost directly from much of the planet. I think it is partly political will codified in economics that is stopping governments from panelling over some of the vast swathes of countryside they own or putting up windmills. But as mentioned we can’t do it all with renewables yet even with massive investment. But if the economic resources that are mustered at the drop of a hat to invade “rogue states” were used instead to address climate change, the real imminent threat to our whole species, we could throw money at building nuclear and modestly invest in renewables for the long term. That’s my best guess with generation. We also need to consume less and have fewer kids on an individual basis.

• charlesrkiss says:

Sorry, nuclear power is absolutely unsafe on a basis of safety to BTU output.

In other words, we’ve been “fortunate” only because nuclear energy provides a largely insignificant percentage of total world energy production.

Throw in another thoulsand plants into your safety equation and see what happens.

• John Baez says:

Charles Kiss wrote:

Sorry, nuclear power is absolutely unsafe on a basis of safety to BTU output.

You’re making this claim without providing evidence, which is (kindly, gently) frowned upon on this blog. If you have access to data on this, it would be very helpful to provide it.

These are full of data:

• Keith Pickering, Hansen: Nuclear power has prevented 1.8 million deaths, Daily Kos, 4 April 2013.

• Pushker A. Kharecha and James E. Hansen, Prevented mortality and greenhouse gas emissions from historical and projected nuclear power, Environmental Science and Technology 47 (2013), 4889–4895.

The first is just a summary of the second, but it’s a bit easier to read.

• Look, the reason fission appears safe is because fission contributes a very small fraction to energy production. Build another thousand plants, and you’ll double the number of failures. Build enough plants to contribute meaningfully energy demand and you have failures in the tens, if not hundreds.

The safety of nuclear power generation will have to increase exponentially for it to be meaningfully safe; and this “safety” would all be speculation compared to the actual numbers we have now, say at a 5 INES level, or greater.

• John Baez says:

Charles Kiss wrote:

Look, the reason fission appears safe is because fission contributes a very small fraction to energy production.

In the US, nuclear contributes a significant fraction to electric power production: it’s wind and especially solar that contribute very small fractions. Here’s the 2012 EIA data:

• Coal 37%
• Natural Gas 30%
• Nuclear 19%
• Hydropower 7%
• Wind 3.46%
• Biomass 1.42%
• Petroleum 1%
• Geothermal 0.41%
• Solar 0.11%

The worldwide figures are comparable.

To me fission appears safe compared to fossil fuels because it causes fewer deaths per megawatt, so replacing fossil fuels with nuclear saves lives:

• Keith Pickering, Hansen: Nuclear power has prevented 1.8 million deaths, Daily Kos, 4 April 2013.

• Pushker A. Kharecha and James E. Hansen, Prevented mortality and greenhouse gas emissions from historical and projected nuclear power, Environmental Science and Technology 47 (2013), 4889–4895.

When discussing these issues it’s important to use statistics, because people’s impressions are not always accurate.

• quakeyjase says:

I agree. Renewables would be much preferable as a long-term solution once we’ve reduced population and consumption to sustainable levels, but that’s not the situation we’ve inherited. We are dealing with unsustainable exponential growth and nuclear fission is realistically what we need in order to hold us until we can rethink the basis of our society along sustainable zero growth lines. In many ways it is the pursuit of growth and return with interest that has poisoned us. It served us well in the past but it’s now driving us into a blind alley. We need a rethink.

• OMG; I didn’t write electricity production, I wrote energy production; what are you going to do about all those quadrillions of BTUs of transport demand? How is nuclear going to put into that? Therefore, “small fraction.”

• John Baez says:

Charles wrote:

OMG; I didn’t write electricity production, I wrote energy production; what are you going to do about all those quadrillions of BTUs of transport demand? How is nuclear going to put into that?

I agree that this is a real problem—but note that it’s a different problem than you were talking about at first. You were saying that nuclear only seemed safe because it represented a small fraction of power generation. I gave evidence that it was safer than the existing alternatives. If this is true, the safety of nuclear power is not an illusion due to how little of it we’re using.

Turning to the new issue: for the US to generate all its electric power using nuclear would only require multiplying nuclear power by a factor of 5. Since nuclear is only good for generating electric power, I think this is a relevant way of gauging how much we might increase nuclear power generation.

Of course, when cars go electric, we could go further. Thanks to the research of Hansen and other I believe it’ll then be safer to generate that electricity using nuclear power plants than fossil fuel plants.

Some other forms of transport (like airplanes) are harder to power electrically, though biofuels amount to a trick for converting solar power to fuel that can power transportation, and in principle you could use any energy source to synthesize fuel.

In the long run I’d prefer solar and wind, but I believe nuclear is a crucial stopgap, given how quickly we need to take action on global warming, and how little solar and wind power currently contribute to our needs.

• quakeyjase says:

Aeroplanes are hard to power with electricity, but what about airships? If you’re not in a hurry (and who says flying for leisure really needs to be done in a hurry), airships could be a very pleasant way of cruising around. Unfortunately we have been talked out of the idea by the mythology surrounding the Hindenburg disaster and the needs of twentieth century military.

• Thank you; but I still have to argue that the “Safety” of a plant isn’t something one measures in “lives” variables (input, output, etc.) only (keyword: “only”), so much as a collection of values, including sick future generations, and property, and other unmeasured, under-represented, parameters of value. This is why fire fighters lose their lives: they know this.

One can’t just take whole sections of the surface of the planet and contaminate them continually, each successive failure compiling over the others!

I think this is an intuitive response to your critique of my point-of-view.

I would like to add, that fission is only good at making bombs, and keeping an educated group of scientists involved in the engineering of predicting the outcomes of nuclear reactions and “controlling” them. I say this in hope, that this knowledge and involvement will increase the likelihood other nuclear reactions will also be engineered and controlled, such as fusion.

Finally, I actually say that this is the only reason fission energy production is a good thing: it merely creates interest at the forefront of physics and engineering, and human knowledge; but as far as an energy source, it has proven to be a failure at this known rate to make any significant impact of total consumption.

But fission also explodes things: immediate output of the most extreme quantities of energy. And that’s pretty good, too.

• John Baez says:

Charles Kiss wrote:

I would like to add that fission is only good at making bombs…

That’s your opinion, but I’ve already heard a large range of opinions on nuclear power, so each additional opinion is of very limited value: it’s mostly useful for updating my estimate of the probability distribution of opinions of people who feel like expressing their opinion. What I want is data.

• Fair enough; I’ll see if I have time to create parameters for measuring safety, and then fill them in with data.

• This “study” ignores the potential loss of life over a span the time where nuclear byproducts are lethal, ie. suppose there is a collapse of modern society, such as happened many times before, and information is lost, and regions of exposure exist that are very high and unknown. Also ignored are the lost opportunities: using limited resources in mitigating radiation damage could otherwise be used in eradicating AIDS, Malaria, Polio, etc.

This study only looks at the past, and makes no account of potential; particularly in an environment where nuclear power is ubiquitous. Nuclear fuel byproducts have a potential for causing damage that far exceeds a coal mine and the burning of carbon; I think this is understood intuitively.

I will try to find a way of quantifying this potential with data. The first calculation I will make is the “death potential” of one gram of Uranium-235 and Plutonium-239, to one gram of coal.

2. Aru says:

It’s all very interesting, especially climate change and so on. But i think the resolution of all the problems is not in technology at all: technology just showed,and accelerated problems of our civilization which were always there. To survive we don’t need new tools, except that we need a new brain. All the great thinkers of all time did not come up with one and probably most important thing – how to create a collective mind, or collective consciousness if you want.

So there is no realistic high level (by high level i mean the level of stable civilizations) method how to govern civilization. Don’t take me politically: it’s a very interesting and mathematical question – “What kind of interaction between two minds will make them stronger mind?” I don’t want to get here in details what is mind and so on. Its obvious that language can not be high level enough for such interaction. So we are doomed, since basically we lack organization structure and we have no high level enough language to make a bigger mind. So our civilization will continue it journey as a beautiful creation of its engineer who could make it to work by ITSELF.

We lack some very important conceptions as a civilization, this is the whole problem, not climate change at all. Scientist should work on that. But again civilization at its scale is too complex for one poor mind and since there is no way to create a bigger mind we are somehow in a loop :) We need bigger mind but we cant design it since the system is too complex. Our hope then is that bigger mind CAN be created from the head of one genius. You can look at our civilization as very complex Internet. Do you seriously think there is a way to govern the whole Internet? Probably there is but we don’t know it.

• John Baez says:

I have no objection to thinking very generally and broadly about these problems: in particular, it seems quite likely that global warming is just a symptom of some deeper problem.

However, I want to know what I can do that will take advantage of my specific skills (science, math, explaining stuff) and accomplish something useful. If a particular line of thought leads us to conclude that we are ‘doomed’, I’ll conclude that it’s not very useful and try some other line of thought? Why? Because I don’t think we are ‘doomed’: we may be headed for a disaster, but disasters come in different sizes, and we can affect the size of the disaster. I would prefer 999,999,999 species to go extinct than 1,000,000,000.

I will, however, be interviewing Eliezer Yudkowsky, who has devoted his life to developing ‘friendly artificial intelligence’: minds better than ours, that might help us with some of our problems. I don’t believe this will be created soon enough to let us escape some of the problems we’re facing — but if it’s possible at all, late is better than never.

• Mariusz Ceier says:

You can save almost all the species, by persuading everyone you know to sacrifice just one species.
http://vhemt.org/
For example you can tell them that giving birth to children is morally wrong, unless they have cure for death and suffering (real one, that could be used all around the world), because otherwise they consciously increase suffering in the world by condemning their children to death (death is afaik inevitable) by breeding.
Some intelligence-test based on similar argument:
http://vhemt.org/biobreed.htm#intelltest

Just an idea.

• Tim van Beek says:

Let’s not forget that humanity is the only species that – as far as we know – is capable to recognize and understand changes in the biosphere and cares about it (which even motivates certain individuals to create blogs about this topic). Did the dinosaurs create wildlife sanctuaries?

Like Q from “Star Trek Next Generation” I consider humanity to be on probation, still.

• zeynel says:

“All the great thinkers of all time did not come up with one and probably most important thing – how to create a collective mind, or collective consciousness if you want.”

This comment assumes that humanity controls its own destiny. It does not. There is already a collective consciousness; in the US it is the “consumer habits” taught to every individual by Hollywood and TV and Mad Avenue. And religion picks up the slack. And a consciousness of nature; “how we perceive nature” is imposed on the individual as a state religion in the form of Newtonian atomic materialism. Materials girls living in a material world.

Consumers are not interested in anything other than having their entertainment drug in ever higher dosage.

Any big change involving a humanity-scale change must come by dealing with the entities that control human individual by programming it. These are legal organisms. They don’t have a human body; so they cannot perceive a change in climate; they only “feel” legal action.

Take BP. BP learned its lessons from Exxon-Valdez incident and knew that it needed to control the public opinion so that there will be no legal action against it by the people. And BP succeeded.

I agree with the commenter that “the resolution of the problem is not in technology at all.” It is a legal problem.

3. Uncle Al says:

how scientists can help save the planet.

It’s been done – birth control. It’s been undone – jackbooted State compassion on all scales; mandatory charity, destruction of the productive to gorge the deserving. An engineer can plan against failure but not against sabotage. Absent personal responsibility, all is lost.

If you want to find the bottleneck, the first place to look is at the top of the bottle. When buying and selling are regulated, the first commodity to be bought and sold is the regulators.

Diversity! Rather than foster brilliance we allocate for its suppression. Best efforts will not substitute for knowledge. WE MUST DO SOMETHING!

What we really need is more surveillance cameras…

• Professor D says:

You are correct.

4. John F says:

What if the Sahara blooms and Siberia melts this century? Warming doesn’t just imply a change in pattern but rather a pattern of increasing change. I think the best defense/domestic/economic/education/energy/etc policy to implement taking the world in a love embrace in the context of climate instability is to fire all of our guns at once and explode into space.

The rise of ancient civilizations evidently required stable climate, e.g. irrigating near large rivers. I think we’re not so ancient anymore. But then again, I’m not only horribly disappointed that we still don’t have a moon base, officially, I’m even more upset that we haven’t starting working on the warp drive yet.

5. Charlie C says:

Just to establish a limiting case, suppose for the moment that somehow the entire world were to switch to nuclear power production for all of its electrical power. How long would the world’s supply of suitable nuclear fuel last?

• bane says:

The answer depends on what you’re prepared to assume will happen in the future.

This chapter of Without Hot Air basically says that, assuming nuclear power has to last 1000 years (giving humanity time to find even more exotic energy sources) assuming mined uranium in current efficiency reactors it can generate 0.55kWh of electricity per global person per day. At the other end of the spectrum, using thorium and assuming the ramp-up energy would be high enough that otherwise uneconomic thorium could be mined, it might be enough to generate 120 kWh/d per person for 60 000 years, with points in between. It’s worth looking at the chapter itself which is much more detailed.

One of my general caveats: as ever it’s worth making sure your beliefs about what’ll be achieved in future are based on what you believe is likely rather than assuming that “everything would be ok if this was achieved” is bound to happen.

• Charlie C says:

Bane, thanks for the input. Let me say a little more about my objective. In order to get a very rough idea of the magnitude of our situation, my objective was to use the simplest possible constraints: assume that the switchover to nuclear power takes place in one day, today, in order to avoid all the complications of ramping up and technology migration/coexistence; assume only today’s power production technology, to avoid the complications and uncertainty of future (more efficient) technologies; assume the use of today’s uranium extraction and processing technologies, and assume only today’s known uranium ore reserves are available; and assume today’s rate of total, worldwide electric power consumption. This approach has a couple of advantages: the data are as accurate as possible, since they they are based on today’s situation and don’t depend on future extrapolations. And the calculations are as simple as they can get. The disadvantage, of course, is that the results are not accurate. But my goal was to get a very rough estimate of whether or not the total uranium supply is likely to be a serious limiting factor in the potential conversion to nuclear power. If the result of this calculation says that we use up the available fuel supply in a few years, then it probably isn’t worth refining the calculations very much — we can easily see that total dependency on nuclear power a non-starter. If the result says we’re all set for the next 1000 years, then fuel is not likely to be a factor. If the result is, say, 50 years. Then it’s time to start refining the assumptions.

The number I’m having the most trouble computing is the number of tonnes of uranium ore need to be mined and processed in order to produce a TWh of electricity.

• Nullius in Verba says:

This may help.

I think the number you want is about 50,000 years, but of course it’s more complicated when you get into the details.

• John Baez says:

I’m sorry that I can’t instantly help you, Charlie, in figuring out how many tons of uranium ore is required to generate a terawatt-hour of electricity. This is the sort of information that a nice wiki would make easily available.

Here are three points that complicate the question you’re interested in:

1) You can get a lot more energy if you use a breeder reactor. According to the Wikipedia article, the “light-water reactor” typically used in the United States produces about 3% as much energy as a breeder reactor, for a given amount of uranium.

2) When we move past the point of peak uranium production, we may expect people to turn to ores of poorer quality, so the number you’re wondering about will rise.

3) There’s about 3 or 4 times as much thorium than uranium in the earth’s crust. There’s about 550 times as much thorium as uranium-235. For this and other reasons, there are many people enthusiastic about thorium-based breeder reactors. It seems that India is the country that’s actually using the most thorium reactors, right now.

• Charlie C says:

I don’t know how to reply to the two responses below, so I’ll just answer here.

@NiV: Thanks for that input. I’ll follow up on it.

@John: Yes, John, this question is impossible to answer accurately. I have some rough, by now probably obsolete figures that may give me a rule-of-thumb estimate for the amount of Uranium ore needed to generate a certain amount of electrical power. But as you and NiV point out, things get very messy as soon as we dig down into the details. Actually, that’s why I decided to go for such a simple approach. When I compute these simple numbers, I see that there are many assumptions being made. I think the assumptions even more interesting than the numbers themselves, because they highlight the problems, understood and not understood, which must be solved along the way. So when we say that we have enough uranium to power the world for the next x-thousand years, there is probably a list with scores and scores of assumptions.

• bane says:

I see your point about wanting a simple calculation in order to get some rough bounds. Just to make clear the point about ramp-up:

Often it requires “using” energy to extract energy (eg, building wind-turbines, mining fuel for a power-plant, etc). One of the problems is that if you can’t haven’t got the requisite resources in advance to extract the energy you can’t do it, even if the overall balance at the end would be an overwhelmingly positive. Of course, there’s even more nuances in that you can’t, for example, use wind turbines with total sufficient “average power output” to run an ore smelter without either going through batteries (to smooth out variability, but thus losing energy in conversions) or having a different backup generator system (again to smooth variability).

• John Baez says:

I hope you succeed in your simple order-of-magnitude calculation, Charlie! Let us know what you get. I’d help you, but I’m a bit distracted by other jobs… this blog can easily eat up all my time if I let it!

• Professor D says:

Sorry for the late comment, but I just found this site. John Baez saying “I don’t know how many tons of uranium it takes to produce a terrawatt of electricity” doesn’t make sense. Power (energy per unit time) is measured in watts. This makes no sense to me. When you are purporting to solve the worlds technical problems, technical accuracy is probably an important detail. But then, what do I know. I’m just a lowly electrical engineer.

• John Baez says:

Professor D wrote:

John Baez saying “I don’t know how many tons of uranium it takes to produce a terawatt of electricity” doesn’t make sense. Power (energy per unit time) is measured in watts. This makes no sense to me.

It doesn’t make sense to me, either. It was a slip of the fingers: I meant terawatt-hour. Thanks for catching it. I’ve corrected it.

But then, what do I know. I’m just a lowly electrical engineer.

We need electrical engineers here! Not to tell us the difference between watts and watt-hours (though apparently that comes in handy at times to), but to help us think about power grids, power plants and much more.

I have been a fan of your website for many years. It turns out I am mathematical physicist too working on helping the Earth to survive human beings! I work on hydrogen applications (apart from my quantum mechanics!).

I am pretty much convinced that the combination of solar+eolic power accumulated in the form of hydrogen is THE option. I would be very interested to know what is your point of view about that??

• John Baez says:

I’m glad you’ve enjoyed my website, César. And I’m even more glad to meet yet another mathematical physicist who is interested in saving the planet!

I am pretty much convinced that the combination of solar+eolic power accumulated in the form of hydrogen is THE option. I would be very interested to know what is your point of view about that??

One goal of the new This Week’s Finds, and the Azimuth Project in general, is to make it easier for people to develop informed and intelligent opinions on these issues.

I haven’t done enough work yet to give a good answer to your question here. So, I would prefer to ask you why you think a hydrogen economy based on solar and wind power is “THE” option.

You probably know this stuff, but it’s worth looking at:

• David JC MacKay, Sustainable Energy – Without the Hot Air, Chapter 25, Living on other countries’ renewables?.

He’s thinking about England, which is not a great place for solar power: one of the first times I went there, a woman told me “It’s a fine day: it’s only raining slightly!” Hence he speaks of other countries’ renewables. He favors concentrated solar power, and discusses the Desertec project. He also discusses wind, elsewhere.

I’m suspicious of the idea that there exists “THE” option for solving the energy problem — a unique best approach that we should all focus on. I hope you’re familiar with Pacala and Socolow’s famous paper:

• Stephen Pacala and Robert Socolow, Stabilization wedges: solving the climate problem for the next 50 years using current technologies, Science 305 (2004), 968-972.

Everyone should read it! It lists 15 measures, each of which could reduce carbon emissions by 1 billion tons per year by 2057.

Here’s an executive summary of what they claim:

• If we adopt 12 of these measures, we could lower our carbon emissions from the current figure of 8 billion tons per year to 4 billion tons per year by 2057. This might mean 450 parts per million of CO2 in the atmosphere by this time, and a global temperature rise of 2 °C (or 3.6 °F). With this, we could still expect coastal flooding that affects millions of people per year. Cereal crop yields will tend to decrease in low latitudes. And up to 30% of species might face the risk of extinction, with most coral reefs being bleached. But this is the "good" scenario.

• If adopt only 8 of the measures, we could hold our carbon emissions constant at the current figure of 8 billion tons per year. This might mean 525 ppm of CO2 in the atmosphere, and a global temperature rise of 3 °C (or 5.4°F). With this, we can expect the widespread death of coral reefs. We can also expect the bad consequences listed above, and: 30% of coastal wetlands being lost, with most ecosystems becoming carbon sources as permafrost thaws and vegetation burns or rots.

• If we adopt none of the measures, we can expect carbon emissions to double by 2057, to 16 billion tons per year. This might mean 800 ppm of CO2 in the atmosphere, and a global temperature rise of 5 °C (or 9 °F). With this, we can expect that more than 40% of species will face extinction. We can also expect the bad consequences listed above, and cereal crop yields decreasing in some mid- to high-latitude regions.

Here are the 15 measures, which Pacala and Socolow call “wedges”. Click for a bigger view!

One can — and should — argue about what they are saying here. But one basic point seems plausible: we need to simultaneously pursue many strategies, and then see how well they work, and focus on the ones that are working best.

• westy31 says:

I am also a physicist, working on hydrogen during the day time, and on fundamental stuff in my spare time.

I agree that we could in principle run our civilization on wind/solar, with the storage in the form of hydroelectric lakes for large scale, H2 when compactness is not important, and synthetic hydrocarbon for planes, where energy per volume or weight is crucial.

The “deeper problem” that John mentions is I think that planet earth is presently experiencing a plague of Homo Sapiens. We can’t help in the usual way (spraying DDT etc), because we *are* the plague. So we try to adapt. We’ve adapted before, but this new adaptation is a on a different level.

I estimate the total cast of the transition at something like 100 000 euro (or dollar) per human being. This is affordable if we spread it out over say 20 years. If you compare this pretty large challenge to something seemingly simple, like ending a senseless war, it may seem hopeless, since ending wars is apparently too difficult already for us in many cases. Fortunately, a war can sustained by a small group of “stupid” people, while a technological revolution can be brought about by a small group of “smart” people. ( I put the smart/stupid qualification in quotes, because it is of course never quite so simple). So it is not hopeless. And besides, I can’t think of anything cooler to do, except perhaps pure science.

I think technology is not the biggest problem. Although it is always nice to have better tools, we could in principle do it on existing technology. The real problem is that doing the required investments (like I mentioned, about 100 000 per human) is not going to happen if we don’t have a good “business plan”. There are just so many options.

Gerard

• John Baez says:

Gerard Westendorp writes:

The “deeper problem” that John mentions is I think that planet earth is presently experiencing a plague of Homo Sapiens. We can’t help in the usual way (spraying DDT etc), because we *are* the plague.

I actually don’t think it’s useful to analogize humans to a ‘plague’.

First of all, even if it were true, it would not be useful to emphasize it. The problems we’re facing are largely political. Politicians need ideas that attract voters. Nobody will win elections by saying “Hi there, voters! You are a plague! I can’t kill you off with DDT, but I can do the next best thing!”

Second of all, I wouldn’t say it’s true. Indeed, it’s not the sort of thing that can be true or false: it’s just an analogy with lots of emotional connotations.

Third, I am quite optimistic about the ‘overpopulation problem’ in the long run if global warming can be limited in the short run. I’m currently reading Stewart Brand’s Whole Earth Discipline, this is making me more optimistic about this issue. I’ll say more later, but for now: fertility drops as soon as people move to cities. People are rapidly moving to cities. So the problem will take care of itself — eventually.

The problem is whether eventually is soon enough!

The best estimate from the United Nations 2004 report is the middle curve here, the orange one:

Here’s what the report says (emphasis mine):

Long-range population projections are reported to 2300, covering twice as long a period as ever covered in previous United Nations projections. These projections are not done by major area and for selected large countries (China and India), as was the previous practice, but for all countries of the world, providing greater detail. In these projections, world population peaks at 9.22 billion in 2075. Population therefore grows slightly beyond the level of 8.92 billion projected for 2050 in the 2002 Revision, on which these projections are based. However, after reaching its maximum, world population declines slightly and then resumes increasing, slowly, to reach a level of 8.97 billion by 2300, not much different from the projected 2050 figure.

[…]

Europe and Africa will be particularly out of phase. Europe will hit its low point in growth in 2050, Africa not till 80 years later, after all other major areas. From 2000 to 2100, Europe’s share of world population is cut in half, 12.0 to 5.9 per cent, while Africa’s almost doubles, from 13.1 to 24.9 per cent. While shares of world population for major areas will rise and fall over the following two centuries, the distribution by 2300 will resemble that in 2100. Smaller regions within continents exhibit divergent patterns. For instance:

• Three African regions — Eastern Africa, Middle Africa, and Western Africa — will grow unusually fast in comparison to every other region through 2100, even though total fertility will be close to replacement by 2050.

• Southern Africa is seeing a decline in life expectancy to a lower level than anywhere else, but life expectancy will rebound, rise quite rapidly, and overtake other African regions.

• Asian regions will grow fastest to the west, slowest to the east, but in every case with growth rates, at least up to 2100, below Eastern, Middle and Western Africa. By 2100, Asia, instead of being four-and-a half times as populous as Africa, will be only 2.2 times as populous.

• Latin America and the Caribbean is the most homogenous major area, with most of its regions following relatively parallel fertility and life expectancy paths.

Northern America is unusual as the only region that will not experience negative growth, mainly due to projected migration up to 2050. (No migration is incorporated in projections beyond that date.)

• Europe, like Asia, will experience higher growth to the west, lower growth to the east. Eastern Europe stands out with low life expectancy, and even in the long run does not catch up with other regions.

I’m pretty sure none of these estimates take into account possible disruptions from global warming and subsequent warfare. And of course there are many unforeseeable possibilities! So, I would give these predictions a fair amount of credence up to 2050, less beyond that, and very little for the last date they consider, 2300.

7. Steve Bloom says:

I have my views on the details, but the important point about the whole nukes vs. renewables debate is that presently we are not on a path toward implementing *any* solution within the needed time, i.e. very, very soon. As of right now, fossil fuels continue to be subsidized on a large scale. While that remains true, it’s arguably just intellectual wheel-spinning to talk about what to replace them with.

Someone above mentioned that we should not forget the prospect of large-scale abrupt events, in particular permafrost melt. I agree.

Re extinction, I don’t think we are at particular risk as a direct consequence of a plausible worst-case scenario (unless we really do burn all of the unconventional fossil fuels). Indirectly we are very much at risk because of our own response to the stress.

• John Baez says:

I agree completely that we need to stop subsidizing fossil fuels! I would like to go much further, and get a carbon tax or cap-and-trade system that would gradually bring fossil fuel prices towards a level that reflects their full cost to the environment.

One major way scientists can help accomplish this is to educate people about the situation we’re in. However, I also think it’s useful for scientists and engineers to turn their energies towards developing the technologies that we’ll need to replace fossil fuels. Among other things, scientists who work on these subjects will make more effective educators!

When you say “Re extinction, I don’t think we are at particular risk”, I hope you are talking about the extinction of the human race. I agree it’s not likely that we’ll go extinct anytime soon. But I worry about other species going extinct. And I worry about large numbers of people suffering.

8. Nullius in Verba says:

There’s a lot to talk about in your long list, but I don’t want to try to address everything all at once. The conversation would just get too confusing.

Since we’re talking about nuclear power, I’ll just point you to a couple of good pages on just one of the many options available.
http://www.nationalcenter.org/NPA378.html
http://www.skirsch.com/politics/globalwarming/ifrQandA.htm

Digging in to those and publicising/popularising the technologies and issues would be a positive step, I think.

For example, I meet a lot of people who have been scared by scientific talk about “half-lives”, thinking that the bigger the number, the more dangerously radioactive the material is. Understanding how the most dangerous part of the waste decays quickly, and knowing about the level of natural radioactivity in the environment that you have to compare it against would be helpful. Do people know about the Oklo ‘natural reactor’ in Gabon? Or how cosmic rays increase with altitude? Or have they ever thought about what it means to have natural Uranium ore deposits in the ground, without any protection or containment?

Incidentally, I can’t resist making at least one comment – you say “the fabled Northwest Passage opened up for the first time in recorded history”. Do you mean apart from when it opened in 1853, 1906, 1921, 1940, 1969, 1977, 1984, 1986, and 2003? “Open” is a somewhat fuzzy term in this context, (as it depends on how fast you can move and how good your timing is,) the difference between ‘open’ and ‘closed’ is small (so only a small change in ice extent might be needed), and the data is somewhat incomplete prior to 1979 when we started getting satellite pictures. Since nobody lives up there, how would we know?

You might want to look up the history of the north west passage (and the north east passage too!) just to fact-check me. And then have a look at where you got the information from.

• Steve Bloom says:

You have novel sources, NiV. Starting e.g. with your 1853 date, as I recall that ship was caught in ice and sunk, although the *crew* made it through via sledge after they were rescued (after three years of being trapped in the ice) by an expedition that had entered from the other side. The first actual passage in 1906 took *three years*. Anyway, open means open for commercial shipping purposes, not just small boats or exploratory expeditions. BTW, discussion of the NWP in this regard is confusing since there are actually three routes, the southernmost of which is too shallow for shipping purposes but has been the only one that could be used until recently.

• Nullius in Verba says:

The problem with the term “open” is that it is time-related, as well. If a path is only open for a day, a ship sailing from the east coast of America to the west would have to be very lucky to get there at just the right moment. To be navigated, the path has to be open for the entire duration of the trip (and you have to know it before you set off), which is a far more challenging requirement than that it be “open”.

As ships get faster and as satellite data provides better navigation, the metric changes.

But I take your point about the definition. Let me know when commercial shipping through there starts in earnest, so we can declare it “open”.

• Steve Bloom says:

Just to add that plenty of people opposed to current nuclear power technology are more than sufficierntly informed on the technical details, including everything you mention. Fourth-gen technology has the advantage of solving a couple of the basic problems, i.e. waste disposal (mostly) and the potential for core melt-downs, but has the drawback of not actually existing.

• Nullius in Verba says:

“…but has the drawback of not actually existing.”

Why is that a drawback?

You can’t be saying “we’re not going to build any, because we haven’t built any yet.”

• John Baez says:

Hi, Nullius. Someday I plan to study nuclear power in much more detail and try to write a readable summary of the pros and cons — thanks for the references. It’ll take me a while to get around to reading them. Once I get the wiki going it will be easier for us to accumulate such references and manage the process of synthesizing the information. Luckily, it’s almost ready!

It’s not deeply important to me whether the Northwest passage had been open at various dates, but it’s always good to get things right. I got my information from the National Snow and Ice Data Center webpage that I linked to upon saying “area of Arctic ice reached a record low in the summer of 2007”. I’m trying to make the sources of all my data as evident as possible without tons of footnotes.

The NSIDC webpage says:

Arctic sea ice receded so much that the fabled Northwest Passage completely opened for the first time in human memory (see Figure 4). Explorers and other seafarers had long recognized that this passage, through the straits of the Canadian Arctic Archipelago, represented a potential shortcut from the Pacific to the Atlantic. Roald Amundsen began the first successful navigation of the route starting in 1903. It took his group two-and-a-half years to leapfrog through narrow passages of open water, with their ship locked in the frozen ice through two cold, dark winters. More recently, icebreakers and ice-strengthened ships have on occasion traversed the normally ice-choked route. However, by the end of the 2007 melt season, a standard ocean-going vessel could have sailed smoothly through. On the other hand, the Northern Sea Route, a shortcut along the Eurasian coast that is often at least partially open, was completely blocked by a band of ice this year.

9. Joe Kaplinsky says:

– I don’t agree we’re ‘annoying the biosphere’. I just don’t find Gaia like ideas plausible, for a variety of reasons. The lesson of evolution is that all the organisms on the planet have evolved in a competitive struggle with each other. Of course that doesn’t say anything about what it’s moral for humans to do. But it does suggest that there isn’t any sort of ‘general interest’ in the biosphere which will defend itself. (You might have a better chance of finding homeostatic processes in physical processes interacting with biogeochemical cycles, but I don’t think you will find them in evolution.)

– I would be even more arrogant than wanting to ‘save the planet’. That’s just stopping catastrophe. If we want to inspire people we should aim higher – beyond just stopping things getting worse, what about making things better? How about improving the planet? We need progress.

– A note on your point that records are tumbling. Records will always be set. To do this right you have to show that there are more record highs than record lows, which is done here.

– I don’t think that overpopulation is a sensible way to try to understand problems. Presumably if you think that overpopulation is a problem then you think there is an optimum population. How would you calculate it? What people do (I don’t just mean how much they consume – people solve problems as well as cause them) is more important than their numbers.

• Steve Bloom says:

Well, I’m part of the biosphere and I’m annoyed! :)

• John Baez says:

Joe wrote:

I don’t agree we’re ‘annoying the biosphere’. I just don’t find Gaia like ideas plausible, for a variety of reasons.

Ugh, I hadn’t meant to open that can of worms here. It’s an interesting can of worms, but I don’t want worms for breakfast.

It was supposed to be obvious that this was just a poetic phrase for ‘causing damage to the biosphere in a way that will lead to effects that hurt us’. But it wasn’t. I will change my wording.

I find some Gaia-like ideas interesting. It’s interesting to try to dream up mechanisms where competing species could lead to a biosphere with homeostatic processes. We’ve already discussed here the limitations of Lovelock’s Daisy World model and a possible way to improve it. But I don’t see much evidence for homeostasis except possibly the faint young Sun paradox. So, it’s certainly not part of the case I’m advocating. And I don’t want people who find the Gaia hypothesis implausible to lose interest in what I’m saying. So in that sense, it’s a can of worms.

• Robert Smart says:

For the record, the anti-Gaia hypothesis goes something like this. What the Earth seems to want to achieve is to maximize its rate of entropy production. The great Australian atmospheric scientist Prof Garth Paltridge showed that this was a good way to understand weather/climate. One of Earth’s best inventions for maximizing its entropy production was life. Intelligent life was even better: getting all that low entropy oil and coal and turning it into high entropy CO2. Its hard to believe that Earth will be happy to go back to lower level of entropy production when there’s all that low entropy nuclear ore around.

Well that’s all fluff, however the Maximum Entropy Production Principle does seem to be important in understanding various relevant phenomena. I guess it’s some sort of Least Action idea. It would be nice to improve our understanding of when it applies and how to apply it. Apparently Dewar’s paper on this has some flaws. Anyway I’d encourage the mathematicians who want to do mathematics to save the world to try to fix this.

• John Baez says:

Tim van Beek pointed out some work on the Maximum Entropy Production Principle in a comment to week294, and pointed us to some papers:

• L.M. Martyusheva and V.D. Seleznev, Maximum entropy production principle in physics, chemistry and biology” Physics Reports 426 (April 2006), 1-45.

• R. C. Dewar, Maximum entropy production and the fluctuation theorem. (Available only with subscription.)

I never got around to reading Dewar’s paper… and I was very confused, because Ilya Prigogine has a quite successful principle of least entropy production that applies to certain linear systems. But Martyusheva and Seleznev write:

1.2.6. The relation of Ziegler’s maximum entropy production principle and Prigogine’s minimum entropy production principle

If one casts a glance at the heading, he may think that the two principles are absolutely contradictory. This is not the case. It follows from the above discussion that both linear and nonlinear thermodynamics can be constructed deductively using Ziegler’s principle. This principle yields, as a particular case (Section 1.2.3), Onsager’s variational principle, which holds only for linear nonequilibrium thermodynamics. Prigogine’s minimum entropy production principle (see Section 1.1) follows already from Onsager–Gyarmati’s principle as a particular statement, which is valid for stationary processes in the presence of free forces. Thus, applicability of Prigogine’s principle is much narrower than applicability of Ziegler’s principle.

Anyway, then David Corfield got me really excited by noting that Dewar’s paper relies on some work by the great E. T. Jaynes, where he proposes something called the “Maximum Calibre Principle”:

• E. T. Jaynes, Macroscopic prediction, in H. Haken (ed.) Complex systems – operational approaches in neurobiology, Springer-Verlag, Berlin, 1985, pp. 254–269.

And I read this paper and got really excited… and then I got distracted by other things.

I need to get back to this someday. Not because it will ‘save the world’, but because it addresses incredibly fundamental issues in physics.

• John Baez says:

Robert wrote:

A note on your point that records are tumbling. Records will always be set. To do this right you have to show that there are more record highs than record lows, which is done here.

I understand that — thanks for the reference. You’ll note that before mentioning the record high temperatures I said:

Between their predictions (in boldface) I’ve added a few comments of my own. These comments are not supposed to prove anything. They’re just anecdotal examples of the kind of events the report says we should expect.

I had some qualms about including these anecdotes but I thought it’d make the rather dry list of predictions more humanly accessible.

In a sense temperature records are a very unrobust way to study temperature trends, since they involve the tails of probability distributions. But one could argue that they’re important, because heat waves and cold spells can have big effects.

In principle, it’s completely possible for a global warming trend to cause greater fluctuations in temperature, and thus an increase in both high and low temperature records. But at least in the US, this doesn’t seem to be happening:

All the references I’ve seen treat the United States; I’d be interested in a worldwide analysis.

• John Baez says:

Robert wrote:

What people do (I don’t just mean how much they consume – people solve problems as well as cause them) is more important than their numbers.

It’s hard to understand this statement, at least in such an unqualified form. For example: if we’re interested in how much energy people use per year, we can multiply the average per capita power consumption by the number of people. Saying the first factor is ‘more important’ is a bit like saying that when you compute the area of a rectangle, the height is more important than the width.

Hmm. Now I’m curious about the numbers in this particular example. Let’s work them out:

From 1980 to 2007 the world-wide usage of power went up from 10 to 16 terawatts. The population went from 4.4 billion to 6.6 billion. So, the power usage per capita must have gone from 2.2 kilowatts to 2.4 kilowatts.

So:

• The power per capita went up about 10%.

• The population went up about 50%.

• The total power usage went up 60%.

So at least in this particular calculation, I’d have to say that the change in people’s numbers was more important than the change in what they did.

I’m not saying this proves anything in general! I just don’t think it makes sense to generalize and say which is more important overall: what people do, or their numbers.

• Nullius in Verba says:

I believe what he means is that the raw measure of resources used is not the best measure of the effect on the environment.

For example, suppose I drive a truck round collecting litter and garbage? Suppose I devote a few hundred kilowatts to cleaning up the effluent from my factory? Suppose I devote time and energy to manufacturing smoke stack scrubbers to clean the soot from power station chimneys? Suppose I carry my garbage home with me?

I’m expending more energy than I have to by doing it that way, but the result is a cleaner, not a dirtier world.

With better technology and greater prosperity, we have more choices about the way be do things. With greater prosperity, we can afford to devote more resources to improving our surroundings. With more people at greater densities, we have a more fertile exchange of ideas, a more optimal division of labour, so the technology to do so moves faster. We move from chopping down the forests to burn the wood, to digging up coal and oil, to nuclear power. As we generate more and more power, we do less and less damage to the environment, because of our growing choices about how we do it.

It has often been said that our ability to care for the environment follows a J-shaped curve as we develop. Things get worse at first, and then they get a lot, lot better.

In fact, there is a fairly widespread body of opinion that things have been getting better!

There is a huge body of statistical evidence supporting this position – one of the best sources on the subject is Bjorn Lomborg’s book The Skeptical Environmentalist. Environmental activists hate it, and have tried hard to discredit it. But the book has been peer-reviewed and is well referenced (over 70 pages of references!) from the best official and academic sources available at the time, and they have had little success. But it’s another one of those contentious debates where neither side seems persuadable. Opinions on it are firmly divided.

It might give you some insight into why so many people are not worried about the state of the world, and hence how you can best address that. But I leave it up to you whether you want to look into it – it would require a considerable investment of time.

• John Baez says:

I own Lomborg’s book, I’ve read it, and as far as I can tell, it’s deliberately misleading when it comes to global warming and the extinction of species. There’s a lot of correct stuff mixed in, too. But I’d really rather avoid spending time quarrelling about Lomborg, and go straight to any references you care to select from his vast bibliography.

It has often been said that our ability to care for the environment follows a J-shaped curve as we develop. Things get worse at first, and then they get a lot, lot better.

In fact, there is a fairly widespread body of opinion that things have been getting better!

The question of whether “things are getting better” is incredibly vague: it seems to serve mainly as a Rorschach test to determine the personality of the person being questioned. Insofar as things are getting better, I’m content; insofar as they’re getting worse, I want to do something about them.

But, I do believe that rich, prosperous societies do a better job of caring for the environment than poor ones. And so, for example, one of my favorite ways of tackling overpopulation is education, particularly of women.

• Nullius in Verba says:

Do you mean that you think he’s accurate but giving the wrong (or an incomplete) impression, or that he’s inaccurate?

I have to say, his position on global warming is one that I respect but don’t agree with, as he follows his usual policy of accepting the ‘authoritative’ science and statistics on any topic and more or less fully supports the IPCC and the AGW theory. What he’s primarily against is the exaggeration and sensationalism you see outside scientific circles. Are you arguing that he’s wrong to do so, or that he misidentifies the sensationalism?

On the question of species extinction, I don’t think there’s any real data. So far as I know, the number of species that are known to have gone extinct over the past few hundred years is a matter of record, and in the neighbourhood of one a year. Do you know of a more comprehensive list? The number we don’t know of is unknown, and the number of new species being created is similarly unguessable. Do you know of any evidence to the contrary that does not come from guesses, computer models, and species-area extrapolation? Because I for one would be interested.

Isn’t the question of whether things are getting better just as vague as the one about whether things are getting worse? Would you agree that this seems to work as a Rorschach test, too? You gave a long list above of ‘things are getting worse’ weather stories, and while you do say they don’t prove anything, I assume you put them in because you wanted the reader to interpret events in that direction.

The weather is indeed a Rorschach test – randomness that we can each pick features from to aid our point. I’m not going to do so, because I’m sure you already know I can. I’m sure you also realise that more and more people are able to recognise it as such.

The importance of addressing our efforts to the actual environmental problems we face, rather than the ones we imagine, is exactly Lomborg’s message. One reason, I think, that he gets so irritated with the environmental alarmists; It distracts and dilutes our attention from the real problems, to the detriment of the actual environment – and none of us want that. Whether or not you agree with him on the specifics of which is which, wouldn’t you agree with that as a principle?

• John Baez says:

I said I don’t want to waste time quarreling about Lomborg, and that’s still true. If I had brought his book to Singapore I might succumb to the temptation of discussing it with you. But since I didn’t, that temptation is easy to resist.

Isn’t the question of whether things are getting better just as vague as the one about whether things are getting worse? Would you agree that this seems to work as a Rorschach test, too?

Sure, I think of these as essentially the same question — and posed at this level of generality, it’s a question I’d like to avoid.

Please don’t take the negative tone of week301 as a sign that I believe things are getting worse in general. I have a lot of trouble figuring out what it even means to say that things are getting better or worse ‘in general’. The ambiguity of this question is why it functions as a Rorschach test.

• bane says:

Nulius wrote

The importance of addressing our efforts to the actual environmental problems we face, rather than the ones we imagine, is exactly Lomborg’s message.

There’s clearly a point about how to respond to uncertain knowledge about what’s “actual” (I know, I’m like a stuck record), but leaving that for now.

I haven’t read Lomborg’s book, because I know I wouldn’t devote the time to adequately analysing it. Assuming the wikipedia article is roughly accurate, then

Moreover, he asserts that the cost of combating global warming would be disproportionately shouldered by poor developing countries. Since the policy combating global warming places unrealistic limits on economic activities, the countries that suffer from pollution and poverty due to the state of their economies will be condemned to continue in such a state. He proposes that the importance of global warming in terms of policy priority may be low compared to other policy issues such as fighting poverty and disease and aiding poor countries, which has direct and more immediate impact both in terms of welfare and the environment.

suggests that he’s concerned about a combination of the enivronment and global equity. This is not going to be a uniformly accepted “value” here, but fundamentally I value “the viability of human society into the indefinite future” more than I value “increasing global equity now and letting the future take care of itself”. (That’s not to say huge efforts shouldn’t be made to increase equity, but if the two come into conflict I’m afraid I’ll choose the future.)

• Nullius in Verba says:

Bane,

“I value “the viability of human society into the indefinite future” more than I value “increasing global equity now and letting the future take care of itself”.”

So do we all. However, there is absolutely no reputable scientific opinion indicating that the viability of human society is in any way at risk. Not from the IPCC. Not from the economic models.

A variety of (heavy) costs and impacts are forecast, and there are arguments to be had over their accuracy, but Lomborg doesn’t dispute any of that. All he is saying is that if you look at what the IPCC reports do say, and the economic models on which they are based, all the more “end of the world” claims are unsupported by science. Nothing is predicted that we couldn’t cope with, or that we don’t already cope with.

Doing so would be at a cost; and it’s a perfectly valid argument as to which cost would be the greater and therefore what our response ought to be. But it does us no good to exaggerate.

I’ll give you another example, to illustrate the point. It was one of the original motivations for Lomborg’s work, and has great relevance for the current debate in terms of how public policy should work, if not in outcome.

(Note, I’m not bringing this example up to say this is the same as AGW – only to say that not knowing the future, we’re faced with the same sort of choice. Try to ignore the inherent appeal to emotion. It’s not intended.)

In the late 1960s, a group of influential scientists and economists warned of impending civilisational collapse due to over population and resource depletion. There would be wars and mass starvation throughout the developing world by the 1980s, spreading to the developed world during the 1990s.

It was inevitable, they said, and the best we could do would be to soften the eventual impact by making some harsh decisions now.

“The battle to feed humanity is over. In the 1970s, the world will undergo famines. Hundreds of millions of people are going to starve to death in spite of any crash programs embarked upon now. Population control is the only answer.” “In ten years all important animal life in the sea will be extinct. Large areas of coastline will have to be evacuated because of the stench of dead fish.” “A cancer is an uncontrolled multiplication of cells, the population explosion is an uncontrolled multiplication of people. We must shift our efforts from the treatment of the symptoms to the cutting out of the cancer. The operation will demand many apparently brutal and heartless decisions.” “Before 1985, mankind will enter a genuine age of scarcity […] in which the accessible supplies of many key minerals will be facing depletion.” “By 1985 enough millions will have died to reduce the earth’s population to some acceptable level, like 1.5 billion people.” “By 1980 the United States would see its life expectancy drop to 42 because of pesticides, and by 1999 its population would drop to 22.6 million.”

As you can see, the threat predicted to human society was even more explicit.

So as a policy maker, and bearing in mind that they didn’t know then what we know now and that the position was widely supported in the public debate, what would you have done? And why?

If you can come up with a good argument, it may be useful.

• Bruce Bartlett says:

John wrote:

“But, I do believe that rich, prosperous societies do a better job of caring for the environment than poor ones.”

I’m very wary of going down that road, as it encourages the people who say that more development, more people, more more is a good thing. Your This Week’s Finds article concentrated on carbon dioxide emissions as a primary measurement for how bad this global warming thing is going to get. Poor countries give off a tiny fraction, per capita (the only reasonable way to measure) of worldwide greenhouse gas emissions compared to rich countries. (That’s before we even factor in historical emissions). They may be poor, they may be burning wood for fuel at an alarming rate, and they may be indiscriminately killing wildlife, but the poor people in Africa, Asia and South America are contributing a tiny fraction of the greenhouse gas emissions of their richer brothers in the developed world. Moreover their daily power consumption is also a tiny fraction of their brothers in the developed world, though of course it’s catching up.

• John Baez says:

Bruce wrote:

Poor countries give off a tiny fraction, per capita (the only reasonable way to measure) of worldwide greenhouse gas emissions compared to rich countries.

That’s true. When I said

But, I do believe that rich, prosperous societies do a better job of caring for the environment than poor ones.

I was being pretty sloppy — in this sentence I was thinking about deforestation, traditional forms of pollution, and other various other things… not global warming.

Maybe it goes like this: rich societies have a greater ability to deal with environmental problems after they’ve decided to deal with them. We haven’t decided to do anything about global warming, and it’s not clear we’ll make that decision in time.

You’re right that rich countries emit a vastly disproportionate amount of carbon dioxide. But it’s also been said that people in poorer countries are too busy worrying about survival and ‘getting ahead’ to care about global warming. Will China and India find a way to ‘get ahead’ without boosting their CO2 emissions to European or American per capita levels? Can we persuade them not to be like us? That’s a really important question.

• bane says:

In response to Nullius several posts earlier. Firstly, just to be clear I was pointing out that it’s quite possible that the values upon which Lomborg, and others, base their calculations may be different from those that others do. As such, it’s not just a case of “look at a cost-benefit analysis” (which I fully agree with), there also needs to be thought about what values are used in the costs and benefits, and people may disagree about them.

Regarding your question, I don’t have a copy of Lomborg’s book so I can’t tell whether the influential scientists were also proficient scientists, whether they were speaking on the basis of evidence or being futurists, and whether those quotes have been subjected to “spinning” somewhere along the line. So the best I can do is say that evidence like this paper on falling rice yields as temperature rises and this paper about the “optimsation” of current relatively small number of monoculture breeds that makes me think that, though by no means certain, there’s enough of a likelihood that I’d rather money/political capital allocated to the future of world as a whole (not humanitarian aid) were put into food crop robustness research, cap-and-trade or some variety of carbon tax than put into, for example, “the project on lowering barriers to migration for skilled workers” or “the ‘government’ project concerned with lowering the cost of starting new businesses” listed here. To be fair, that page makes it very clear that the goal (i.e., value driving the analysis) is “advancing global welfare”, where trading off an uncertain future for more certain results for the current population is reasonable.

• Nullius in Verba says:

Bane,

“So the best I can do is say that evidence like this paper on falling rice yields as temperature rises…”

Thank you. I understand the paper presents empirical evidence that the rate of growth in yield has decreased, not that the yield has decreased. (The second derivative is negative rather than the first. Yields themselves are still rising.) The records from individual farms are mostly very short – the longest being 6 years, ranging down to 2 or 3. They compared the short-term yield records against the averaged 26 year trend from a global temperature dataset (I’m not sure which dataset they used). The projection of future reductions in actual yield are based on the usual modelling work, which is acknowledged to be very poor at predicting local changes in climate. And even that (as they acknowledge) assumes we take no measures to adapt.

That’s the sort of thing I mean. You read the press releases and news stories and get one impression, and then you look at what the science and data actually says and get another.

That’s exactly what Lomborg’s book is all about.

But please don’t take that as any sort of criticism. In presenting the evidence on which you based your conclusion, you did exactly the right thing, (and you’re doing a far better job of it than me). And given the general tone of the media coverage of the paper, I’d say your conclusion was reasonable. I’d like to see the exchange as a hopefully positive step.

• Steve Bloom says:

Er, NiV, but based on what you say you didn’t go straight to the science and data (i.e. the paper). Out of curiosity, where did you get your information?

Also, Lomborg’s book peer-reviewed? Source for that claim?

I assume also that you’ve reviewed the extensive documentation of his errors available on the internet?

• bane says:

FWIW, it wasn’t the media response that made me think it said a falling yield, I was trying to figure out what conclusions it drew from the abstract (since unfortunately I don’t have academic journal access at the moment).

• For a summary of “peer reviews” of Lomborg’s stuff see http://www.lomborg-errors.dk/skeptical.htm

Mentioning Lomborg should earn a good score on the climate crackpot index.

• Conventional wisdom based on previous research held that land plant productivity was on the rise. A 2003 paper in Science […] showed that global terrestrial plant productivity increased as much as six percent between 1982 and 1999. That’s because for nearly two decades, temperature, solar radiation and water availability — influenced by climate change — were favorable for growth.

Setting out to update that analysis, Zhao and Running expected to see similar results as global average temperatures have continued to climb. Instead, they found that the impact of regional drought overwhelmed the positive influence of a longer growing season, driving down global plant productivity between 2000 and 2009. The team published their findings Aug. 20 in Science.

“This is a pretty serious warning that warmer temperatures are not going to endlessly improve plant growth,” Running said.

• Nullius in Verba says:

Florifulgurator,

“For a summary of “peer reviews” of Lomborg’s stuff…”

Yes, I know about it. I also know about Lomborg’s 185-page reply to all the points, pointing out errors in the criticism. (In Danish, unfortunately, but some of it has been translated.) I notice you didn’t mention that.

In most cases I’ve looked at, the criticism is simply that Lomborg has not presented every aspect of the problem in depth, so that you can see the arguments for and against his thesis, and in particular, those against. (i.e. he chose not to argue against his own case.)

This fails on two points:
– that we already know the argument for the other side, which has been presented to the public exclusively – and with a premium on space, and with a need to balance up an unbalanced debate, Lomborg has to concentrate on presenting the new information;
– the same criticism applies with even greater force to the more alarmist picture, who even with greater resources and media access have been slow to present arguments and evidence against their own position. Have they critically examined their own work with anything like the same enthusiasm? They have been tolerant of errors and gaps in works they support; it would be misleading to set a different standard for works they oppose.

“Mentioning Lomborg should earn a good score on the climate crackpot index.”

On what basis? That he puts forward a view that you don’t agree with?

Any sort of ‘crackpot’ index has to judge on the basis of methods, not conclusions. In particular, the use of fallacies and illogical arguments – argument from authority, confirming the consequent, correlation implying causation, argument from ignorance, argument ad populum, argument from adverse consequences, use of anecdotal examples rather than data, cherrypicking, definitional retreat, etc.

Mentioning Lomborg, so long as it is not done as part of argument from authority (i.e. it’s credible because Lomborg said it) and so long as it is noted that there are criticisms which a careful reader might want to follow up (which of course I did) is no more a fallacy than any other citation. Lomborg clearly relies on reasonably reputable data, checks sources, and remarks on their limitations. Compared to other popular science books aimed at the general public, there’s a lot more evidence, references and statistics presented than is usual. At first glance, and without being an expert in the subject, there’s no obvious reason to classify it as “crackpot”.

(Just as I wouldn’t classify the IPCC reports as “crackpot”, even though I think much the same of them as you do of Lomborg.)

The only reason I can think of for you to expect a non-expert to be suspicious of it is that it comes to the “wrong” conclusion. And any argument proceeding from conclusions in that way is itself fallacious and therefore quite possibly “crackpot” itself.

John,

While we’re at it, I’d like to ask you what your policy on use of the word “crackpot” is? On the whole, I’m happy to see ad hominem being used by the other side, but I’d like to know that I’m playing on a level playing field. Up to now, I’ve been very careful about my use of language – something I intend to continue – but I’d feel a little more relaxed about it if I knew where the boundaries were, and that others were respecting them too.

• John Baez says:

Calling anyone a “crackpot”, or some equivalent term, is strongly discouraged on this blog — and forbidden when referring to somebody else posting on this blog. I also discourage further discussion of Lomborg, at least on this particular blog entry, because I want to focus attention on science, and this is taking us away from that. Especially in the field of climate change, as soon as we move from from science to the merits of a particular person, the comments gradually tend to degenerate into a Punch and Judy show.

Thus, I’ve deleted two posts by Nullius and Florifulgurator which were solely focused on Lomborg and whether or not he is a “crackpot”.

10. Bruce Bartlett says:

Congratulations on the first “This Week’s Finds”. Let’s try and save this place. I must say, the thing I don’t like about the George Carlin stand-up is this notion that somehow we are insignificant in comparison with the earth; that somehow the earth is so huge and so massive and it will one day just flick mankind away as a dog shakes off fleas from its back. I think many people think that way; it’s a very convenient idea to have because it takes responsibility away from us; we’re so insignificant and all compared to mountains and earthquakes so let’s just carry on business as usual and not be so arrogant as to think we actually matter to the world at large!

I don’t think it’s true: I think we -are- significant on a “cosmic” scale to the earth and its history. For instance, my understanding is that, if we pooled all our resources together and we so wanted, we could build an almost-arbitrarily large thermonuclear bomb which when set off could certainly equal the impact of any of the meteor impacts in earth’s history; heck we could probably perturb the earth out of its orbit. Am I right in this? It’s an important point because many people simply think that even with all our technology we are still so “small” and “insignificant” when compared to big mother earth.

• John Baez says:

Hi, Bruce! Our pal Andrew Stacey has gotten the Azimuth Project wiki running, and soon I’ll get to work on that.

… my understanding is that, if we pooled all our resources together and we so wanted, we could build an almost-arbitrarily large thermonuclear bomb which when set off could certainly equal the impact of any of the meteor impacts in earth’s history.

What a brilliant plan! We could solve all our problems in an instant!

Am I right in this?

I actually doubt it. The asteroid impact at Chicxulub was far from the biggest our Earth has survived, but it probably helped kill off the dinosaurs, and Wikipedia estimates its energy at 4×1023 joules, equivalent to 100,000,000 megatons of TNT. That seems hard to top. As a point of reference, the megatonnage of the US nuclear arsenal is currently around 1,430.

But your overall point is right. I think a better way to illustrate it is to note the percentage of various biosphere flows that are now used by humans. Maybe someone can find more numbers, but how about this:

… end consumption by people raises the total human appropriation of net primary production to 23.8% of potential vegetation. It is estimated that, in 2000, 34% of the Earth’s ice-free land area (12% cropland; 22% pasture) was devoted to human agriculture.

11. crazy bill says:

I think that one of the key issues you’ve identified is the one about “negative externalities”. This is something that seems to be generally misunderstood or ignored by those who deny that there is a problem. And yet it goes to the core of the “problem” that industrial society is causing to the biosphere. It is also the core reason why political opposition to “saving the planet” is so strong – giving up the free use of these “externalities” really will impose large costs on many people, business interests, and indeed entire economies. And the issue of “externalities” that impact the community impacts most heavily on libertarian-type political philosophies that say individuals have no “moral responsibility” towards the wider “community”.

So one thing that scientists (not just physical scientists, but those who study human relations as well) need to do is to really clarify the reasons that we as a society and as individuals need to “care about” screwing up our environment.

• John Baez says:

I agree wholeheartedly. Some people don’t seem to notice the vast array of mechanisms that support modern societies by preventing externalities that once caused a lot of trouble. These mechanisms didn’t all spring into existence on their own — many of them took a lot of work to develop, and many of them rely on the force of law. If you pay attention to all this, it becomes plausible that there are other externalities that still need tackling today. And then you look around and you see them.

12. John Sidles says:

Save the world? Ed Wilson’s new novel Anthill gives a succinct prescription (p. 348):

“Raff lived by three maxims. Fortune favors the prepared mind. People follow someone who knows where he’s going. And control the middle, because that’s where the extremes eventually have to meet.”

In the context of the rest of the novel, Raff’s three maxims are Ed Wilson’s carefully conceived prescription for saving big chunks of 21st century Alabama … and by extension, the 21st century world.

13. Richard Séguin says:

John,

14. John Baez says:

I’m pleased with how civilized this conversation has been. It gives me hope that together we can figure out some of the complex problems we’re trying to understand here. True, one person tried to post a comment saying I was “crazy” — without explanation, alas — and one otherwise pleasant commenter suddenly took it into their head to call another one “moronic”. I deleted these comments, and repeat offenders will be permanently banned. But in general it’s wonderful to see how friendly and cooperative people can be, at least under close supervision by a benign despot with total authority.

(More sophisticated forms of governance are rumored to be more effective in the long run, but this seems to be working for now, here.)

15. Just a couple of quick points regarding externalities:

1) If you’re going to address population issues, it would be a great mistake to overlook the *positive* externalities of population growth. An externality is a cost or benefit that’s not accounted for by the decision maker. For example, this blog is a positive external benefit of your parents’ decision to have a kid; presumably they did not account for the benefits of the blog when making this decision. More generally, the ideas and diversity that people bring into the world are big positive externalities, and I think it’s highly plausible that they outweigh the negatives, which would imply that the population is generally growing too slowly, not too fast.

2) It is a major (Nobel-winning) insight of modern economics that all externality problems are symmetric. If you’re walking by my window when I dump my waste bucket, I’ve imposed an externality on you. But at the same time, your presence below my window creates pressure for me to be forbidden to keep throwing waste, or at least to be taxed for it — and that imposes an externality on me. (This is not in any way an assertion of moral symmetry, but if you’re arguing on efficiency grounds, it’s a key *economic* symmetry.) The upshot is that it might very well be optimal to tax my waste-throwing — but alternatively, it might be optimal to forbid you from walking under my window and allow me to keep throwing waste at will.

Pigou believed that once you’ve identified an externality, it’s always optimal to tax it, and that mistake has become widely disseminated among non-economists. We now know that the problem is much subtler than that, and that sometimes the best solutions are the counterintuitive ones.

• John Baez says:

More generally, the ideas and diversity that people bring into the world are big positive externalities, and I think it’s highly plausible that they outweigh the negatives, which would imply that the population is generally growing too slowly, not too fast.

I find that conclusion highly implausible, which means we’d actually need to get some data — and think about the right way to study it — before we came to an agreement. Somehow we’d need to tackle the fact that birth rates are higher in poorer countries.

So, the richest countries are starting to complain about underpopulation, while the poorest ones are complaining about overpopulation. It’s not a homogeneous situation.

• I find that conclusion highly implausible, which means we’d actually need to get some data — and think about the right way to study it — before we came to an agreement.

For starters, we’d want to think about what the negative externalities actually are. Here it’s important to keep in mind that consumption per se imposes no external costs. The stuff you produce and the stuff you trade for comes at no cost to anyone. The stuff you inherit (which can be substantial) comes at a large cost to your siblings, who would have had bigger shares if you hadn’t come along, but that’s presumably something your parents were aware of when they chose to have you, and as long as the parents cared about the siblings, this cost is not external. (In other words, your parents thought you were worth having even after accounting for the cost to your siblings.)

Likewise, overcrowding is not a significant external cost, because the world is full of empty space. The choice to live in a crowded place instead of an uncrowded place is voluntary, often driven by the fact that crowds come with more opportunities to earn income, making them, if anything, a net positive externality. You can’t count something as a cost if it’s easy to escape.

So what are the big externalities associated with having another child? As far as I can see, they are the prospects that the child could grow up to be a thief, a conqueror or a major polluter. You’d have to argue that these negatives outweigh the positives of a lifetime of interaction with people who love you, plus (and this is a huge one) a lifetime of ideas that are easily imitated and in that sense live forever, plus contributions to the world’s diversity, plus (just by virtue of adding to the population) an increase in the potential gains from specialization and economies of scale.

All this goes out the window if you think that a substantial number of children are unplanned, so that we can’t think of parents as decisionmakers. But the evidence from many times and many places indicates that family size responds quite sensitively to changes in economic conditions, in exactly the ways you’d expect if most children were planned.

• John Baez says:

Steven wrote:

So what are the big externalities associated with having another child? As far as I can see, they are the prospects that the child could grow up to be a thief, a conqueror or a major polluter.

Since almost everyone in the developed world is a major polluter when it comes to CO2 emissions, the last is the one I’m most concerned with. A special feature of this externality is that the bad effects are likely to become apparent only in the future. In undeveloped countries, many people contribute to deforestation, a negative externality whose bad effects also take a while to become fully apparent.

I don’t have the energy to think about this very seriously on a lazy Sunday morning — it’s a fascinating and complicated subject, but I’m just lying here in bed sipping coffee, making sure folks didn’t start insulting each other while I was asleep. So, I’ll just mention a few things I read here:

With education, women become much less fatalistic regarding their family size. As Cochrane notes in a study of fertility in Nigeria, only 10 per cent of the women with education beyond the primary stage believed fertility to be ‘determined by God’, whereas 50 per cent of the totally uneducated women held that belief.

In gender-stratified societies, as in South Asia, son preference is a common feature. If a couple desires to have two living sons, they will end up having 3.9 children on an average. If parents want at least one daughter and one son, the average would turn out to be 3. Thus son preference increases the family size significantly in the long run. Chowdhury finds that in Bangladesh son preference is so strong that even education above primary level cannot counteract it. Cleland and Jejeebhoy suggest that very high levels of education are required in order to counter the preference for sons in such societies.

There appears to be a positive relationship between the education of women and contraceptive knowledge. Cleland and Jejeebhoy argue that “the role of schooling becomes more apparent in terms of detailed knowledge: the number of methods, especially non-terminal methods, known; the correct use of a particular method; and from where a particular method can be acquired.” For example, they refer to a study showing that in India, 95 per cent of the women with secondary education knew about the IUD whereas only 39 per cent of the uneducated women had the knowledge of this method of birth control.

In many developing countries, it has been observed that even women who are highly educated do not have an adequate understanding of reproductive physiology — upon which the success rate of traditional and modern contraceptive methods depend. Moreover, there still exists a large gap between knowledge and actual practice of contraception.

• Tom Leinster says:

One of my favourite charities is Camfed (Campaign for Female Education). It works on the principle that in developing countries, increasing the level of education available to girls is an extremely effective way of bringing about positive social change:

When you educate a girl in Africa, everything changes. She’ll be three times less likely to get HIV/AIDS, earn 25 percent more income and have a smaller, healthier family.

The evidence backing up these claims is highly persuasive.

16. Philip Gibbs says:

What is the model used for the Carbon Dioxide Stabilisation curves? They seem to show that no matter how much CO2 is cut-back the amount of atmospheric CO2 will not decrease. Is that correct? The measurements of atmospheric carbon dioxide show that it goes down during part of the season, so it seems odd that it would not go down if we stop putting CO2 into the air.

I am not asking this as a skeptic. I just want to understand the physics behind this.

• Nullius in Verba says:

You might find it useful to look up the “solubility pump”.

As I understand it, about 2 ppm is currently absorbed per year by natural sinks, which is about half the human contribution. (i.e. CO2 is going up half as fast as it would if all our CO2 stayed there.) This is probably going into the oceans – either by direct solution, or via the biology – but I don’t think anyone is very sure. They may even have miscounted – the carbon cycle has a fair degree of uncertainty in some of the numbers.

I understand that some of the models predict an eventual saturation of these sinks, which is one of the reasons why the global warming is predicted to accelerate so fast over what we have seen so far.

• Philip Gibbs says:

Thanks for the pointers.

If the carbon dioxide continued to be removed at 2 ppm/yr then the blue curves on the upper plot would be heading down, not leveling off. I suppose the model used is assuming that the carbon sink is being saturated, despite the uncertainties you speak of. So these look like they are conservative plots.

It would be nice to know more about the uncertainties and it would be good to see how these curves look given a model that is less conservative but still plausible.

• Philip Gibbs says:

In case anyone thinks I am being a denialist, I’d also like to see how the curves would look with the kind of positive feedback that some people suggest could happen. I am just interested in how the uncertainty affects the curves either way.

• Nathan Urban says:

Here is a model intercomparison which shows some of the uncertainties in the carbon cycle response to future emissions, and here for a comparison of carbon cycle uncertainties to other climate uncertainties. Those papers don’t look specifically at stabilization scenarios. This paper does (for temperature, not CO2 stabilization).

• Nathan Urban says:

Phil wrote:

What is the model used for the Carbon Dioxide Stabilisation curves?

According to John’s link to Wikipedia, they were derived using a modified version of this model by Wigley.

They seem to show that no matter how much CO2 is cut-back the amount of atmospheric CO2 will not decrease.

They were explicitly constructed as “stabilization curves”. That is, assuming you want CO2 to asymptotically approach some constant value, what emissions trajectory will cause that to happen?

The measurements of atmospheric carbon dioxide show that it goes down during part of the season, so it seems odd that it would not go down if we stop putting CO2 into the air.

Right, but those curves don’t show a scenario in which we stop putting CO2 into the air. They show scenarios in which CO2 emissions are cut drastically, but not all the way to zero (within the time frame considered). See the lower panel of the figure.

• Steve Bloom says:

This was analyzed in a paper that was discussed a few months ago at RealClimate. It turns out that atmospheric CO2 starts to drop fairly soon if emissions go to zero.

• John Baez says:

Thanks, Nathan!

You wrote:

According to John’s link to Wikipedia…

It was actually the Global Warming Art wiki. But you got the key idea: in the new series of This Week’s Finds, I’m trying to make the sources of my information pretty easy to find without burdening the text with footnotes. I encourage everyone else to do the same! It’s easy to link to your sources — and your arguments will be a lot more credible, and checkable, if you do.

So: if you’re wondering about the source of some information in This Week’s Finds, just click on the nearest link. If you’re wondering about the model behind those climate stabilization curves, just click on those curves and read the stuff. Soon you’ll get to Wigley’s paper. I also cited this:

Carbon is forever, Nature Reports Climate Change, 20 November 2008.

which is a good starting-point for accessing more recent literature.

(I would love to write a This Week’s Finds about this… but there’s a lot to talk about, so I’m not sure if I’ll get around to it.)

Steve wrote:

This was analyzed in a paper that was discussed a few months ago at RealClimate. It turns out that atmospheric CO2 starts to drop fairly soon if emissions go to zero.

Do you mean this?

• Steve Bloom says:

That’s the one, John. As noted in the comments, what would happen with temperature in the real world is a different story than the paper discusses since if CO2 emissions go to zero so would aerosol emissions. In addition, the CO2 that’s already present may be sufficient to trigger major warming feedbacks before the sinks can draw it down. Of course, immediate zero CO2 emissions isn’t exactly the real world to begin with.

17. “The population is still climbing fast, though the percentage increase per year is dropping.”

I still see value in what my mentor in sociometrics and public policy, Herman Kahn, Physics post-doc tuned futurist, military strategist, systems theorist, was doing in making best fits of Logistic curves to these putatively exponential growths.

The Year 2000: A Framework for Speculation on the Next Thirty-Three Years, (MacMillan), ISBN 0-02-560440-6

Herman Kahn (February 15, 1922 – July 7, 1983) was one of the preeminent futurists of the latter third of the twentieth century. In the early 1970s he predicted the rise of Japan as a major world power. He was a founder of the Hudson Institute think tank and originally came to prominence as a military strategist and systems theorist while employed at RAND Corporation, USA. He was known for analyzing the likely consequences of nuclear war and recommending ways to improve survivability.

His theories contributed to the development of the nuclear strategy of the United States….

18. Richard Errett Smalley [6 June 1943 – 28 October 2005) was the Gene and Norman Hackerman Professor of Chemistry and a Professor of Physics and Astronomy at Rice University, in Houston, Texas. He was awarded the Nobel Prize in Chemistry in 1996 for the discovery of a new form of carbon, buckminsterfullerene (“buckyballs”) (with Robert Curl, also a professor of chemistry at Rice, and Harold Kroto, a professor at the University of Sussex)….

Smalley attended Hope College before transferring to the University of Michigan where he received his B.S. in 1965. Between his studies, he worked in industry, where he developed his unique managerial style. He received his Ph.D. from Princeton University in 1973. He completed postdoctoral work at the University of Chicago, with Lennard Wharton and Donald Levy, where he was a pioneer in the development of supersonic beam laser spectroscopy.

Richard Smalley

In his later years, Smalley was very outspoken about the need for cheap, clean energy, which he described as the number one problem facing humanity in the 21st century. He felt that improved science education was key, and went to great lengths to encourage young students to consider careers in science. His slogan for this effort was “Be a scientist, save the world.”

Skeptical of religion in general for most of his life, Smalley became a Christian shortly before his death. (See the Wikiquote for his personal statement in May 2005.)

In some of his later presentations, he presented a list entitled “Top Ten Problems of Humanity for Next 50 Years”.
[Top Ten Problems of Humanity for Next 50 Years”, Professor R. E. Smalley, Energy & NanoTechnology Conference, Rice University, May 3, 2003.]
His list in order of priority is:

1. Energy
2. Water
3. Food
4. Environment
5. Poverty
6. Terrorism & war
7. Disease
8. Education
9. Democracy
10. Population

… He was an outspoken critic of the idea of molecular assemblers, as advocated by K. Eric Drexler and introduced scientific objections to them. His two main objections, which he had termed the “fat fingers problem” and the “sticky fingers problem”, argued against the feasibility of molecular assemblers being able to precisely select and place individual atoms. He also believed that Drexler’s speculations about apocalyptic dangers of molecular assemblers threaten the public support for development of nanotechnology. He debated Drexler in an exchange of letters which were published in Chemical & Engineering News as a point-counterpoint feature.

19. Orr says:

“How can scientists save the planet?”
They can start by traveling less, much less.

• John Baez says:

I agree. Scientists need to talk, face-to-face… but we live in a marvelous age where it’s free to have a video conversation with anyone who has an internet connection! Now that I live in Singapore, I’m continuing my weekly meetings with my 5 grad students back in the United States… using Skype.

I’ve tried to break the habit of going to conferences merely because I’ve been invited to speak
and it’s ‘prestigious’. (Being a skinflint, I’ve always found it easy to resist going to conferences when I had to pay for travel.) I find it’s nice having more time to think.

We also need to get better at video conferences. There’s going to be one soon, on the subject of loop quantum gravity. I was invited to blog about it. You’ve just convinced me this could be a good opportunity to advertise the virtues of video conferences.

But because the most important conversations at conferences often happen over lunch or dinner, I keep hoping that someone will open a chain of restaurants equipped with high-quality video links that let you talk and eat with someone in a distant city. The idea: a table facing a wall-sized video screen showing the other half of an identical table in an identically furnished restaurant in another city. Same menu, so you can compare choices with your colleagues just as in a normal restaurant! For more cities, divide the table in thirds or quarters. Conference organizers or businessmen holding meetings could book a number of these rooms in a number of big cities.

Maybe it’s not economical yet. Maybe oil prices need to rise more before it becomes economical.

Quite generally, communication should tend to replace transportation as oil prices rise. Especially air travel: we can build battery-powered cars, but we can’t build battery-powered passenger planes.

But also, every time I see the crush of traffic on the Los Angeles highways, I think about the virtues of telecommuting.

• Steve Bloom says:

I suspect we’ll be seeing the return of blimps/dirigibles in the not too distant future. A big advantage is that they don’t require large airport facilities, so travel time might be better or at least no worse for shorter-range trips.

• bane says:

An important precursor is to figure out what you want a tele-academic-conference, and telecommuting in general, to achieve. To a certain extent, if you’re a high-level nabob in some university, your subset of the scientific community or have some other claim to fame, you can ask pretty much anyone to talk to you and they will. At the other end of the spectrum, grad students and post-docs often have various “physical” cues at a conference that will mean that they can get to talk to lower level people interested in what they’re doing, and maybe get at least seen by a couple of the upper echelon people interested in that area.

For example, I don’t know if pure mathematics has poster sessions — everyone sticks an a0 poster describing your stuff up and stand next to it for 2 hours — but they’re partly build upon physical cues: if I’m standing at the front of a couple of people looking at your poster, it’s understood that it’s ok for me to be the primary one asking you questions, and equally the physical presence of those behind me is a reminder I shouldn’t monopolise your time. Similarly, I can look at a neighbouring poster keeping track out of the corner of my eye to move in once the crowd moves away. If you have a virtual poster session, it wouldn’t be not too hard to set up a “talk to owner” button, but you really need to come up with an interaction/feedback scheme that promotes desirable results.

Likewise, anything electronic faces the fact that we’re still figuring out “natural” degrees of visibility of statements electronically. For example, I might say to someone I know over coffee that I think a given presentation has “set a new record for dividing an idea into Minimum-Publishable-Units”. In real life, nothing stops someone nearby recording me and making this public and, if it came down to it, I would stand behind anything I’ve ever said, but for reasons of an easy life/not being unnecessarily hurtful I don’t intend those statements to be easily findable automatically. But all of the electronic technologies we have tend to assume global, automatic-search visibility, with an option to ask search engines not to index a particular copy of the data (but you might not be the only one with a copy of the data), so you might well end up with either the facebook effect (people trying to disassociate themselves from things they didn’t expect everyone to see) or everyone being so hyper-careful that relationships and ideas don’t develop as they currently do. (It’s amazing how much bonding seems to happen when you both agree over a beer that respected group X’s lauded clutch of papers at the conference are actually a load of ********.) This is something most of the social networking sites are researching right now: a list of checkboxes isn’t a substitute for the physical cues we use to unconsciously keep track of what context we’re in. Eg, you’re familiar with the shift in conversation topic that happens when you peripherally see someone (who possibly has to be rather than wants to be) “respectable” approaching; technologists need to figure out a way to do this in abstract communications.

So the technology is hard but probably doable, but we need to figure out what the technology should really be doing to optimise the goals.

(Incidentally, that’s why I use a pseudonym on blogs: regrettably even given the care I’ve taken separating thigns, web searches show up several “informal” comments I’ve made before any of my “authoritative” papers comes up.)

• John Baez says:

Bane wrote:

At the other end of the spectrum, grad students and post-docs often have various “physical” cues at a conference that will mean that they can get to talk to lower level people interested in what they’re doing, and maybe get at least seen by a couple of the upper echelon people interested in that area.

Good point. I only started going to lots of conferences after I got tenure — due to some spectacular lack of understanding of how scientists get jobs, together with the luck of fools. So I tend to neglect the ‘getting to know people in the first place’ aspect of conferences. But I did break into quantum gravity and then category theory after getting tenure, so I did do a lot of standing near the edge of a circle of people, hoping they’d pay attention to me. So in fact I should be able to keep this aspect of conferences in mind!

For example, I don’t know if pure mathematics has poster sessions — everyone sticks an a0 poster describing your stuff up and stand next to it for 2 hours — but they’re partly built upon physical cues…

We don’t have lots of poster sessions in math, but we do have some, and of course I’ve been to lots of physics conferences, where they are more common. So yeah: developing an online version of this would be an interesting challenge.

It should be doable.

I just had a somewhat obvious idea. How about doing a conference in a virtual world like Second Life? I bet someone has already done it. I’ve never used Second Life or anything like that, but it can’t be that hard, given how many people do — and it should be pretty easy to stand by a “poster” and size up passers-by to see who looks interested.

Of course one downside of Second Life is that people use it for all sorts of disreputable activities, which might scare away conference organizers. But it should be easy to create or wall off more stuffy, formal virtual worlds for business purposes… and I bet the Second Life people are already busy trying to tackle this problem.

One upside of something like Second Life is that you could have a conference on astrophysics on a starship cruise to a black hole!

Or: a conference on molecular biology in a hotel that shrinks to fit inside a cell and then visits various organelles!

And so on.

(Incidentally, that’s why I use a pseudonym on blogs: regrettably even given the care I’ve taken separating things, web searches show up several “informal” comments I’ve made before any of my “authoritative” papers comes up.)

Ah, I wondered about that. Personally I decided long ago to keep a single unified identity. I need to be more careful about what I say, but on the other hand, people are more likely to listen — since the more you talk, the more people listen, as long as you say reasonably interesting things.

• bane says:

Second life (and other VR technologies) is certainly a reasonable approach. However, I think it’s possible to do this for more abstract “video-window” style telecommunication. As an analogue, it’s easy to forget how “weird” the conventions of single-clicking, double-clicking, right- and left-clicking with a mouse are, but people learn semi-conscious associations between what they want to do and the mouse click pretty well. It’s more of a case of needing appropriate people to “extract” all the interactions that need duplicating and other appropriately trained people formulating an effective interaction scheme embodying them.

20. Robet says:

You may want to drop the automatically generated “Possibly related posts” thing at the bottom of the articles. It seems that your mention of crystals of calcium carbonate triggered a link to a page promoting healing by magical crystals. It dosn’t give a good impression, especially when “related posts” in other blogs are usually by the same author. :-)

• John Baez says:

Sometimes these automatically generated links are stupid. But sometimes they seem interesting. So I couldn’t decide whether to get rid of them or not.

But you just made up my mind. They’re gone!

21. John Baez says:

By the way, if you don’t like the skinny-column blog format for This Week’s Finds, you can see “week301” on my homepage here. I’m not sure I’ll keep doing this, but it’s sorta nice having it on my own site.

22. westy31 says:

Well, the word ‘plague’ may sound a bit insulting. I actually quite like Homo sapiens. But what if you asked gorillas, polar bears or tunas? What would happen if they had DDT sprays, would they use them against us?

Even though the population will stabilise at 9 billion, we also have to face the fact that we increase what we consume per human. We eat 150 watts, but now use an extra 3000 watts because of our way of life.

OK, I want to be constructive. The negative emotional connotation of a plague may prevent it from working as a political slogan. But it is interesting to think *why* we dislike plagues. Nature is a somehow a constant competition for food, and biodiversity is the result of the fact that no species has ever won. (although losing, ie extinction, is very common) Plagues happen when finally, a species really does its homework. What if a plant managed to grow very efficiently, and be very poisonous to herbivores? It might cover the earth at the cost of all other life. Why has this not already happened? Would it be bad if it did?

One reason I don’t want to drop the plague idea just yet is the tendency to romanticise the idea of living in harmony with nature. Partly this is impossible. Even if we were all vegetarian, we will always have to stop other animals eating our agriculture. You can’t have a field of extremely tasty food, and stop other animals from eating it in a natural way. For each extra human being, there have to be less other organisms competing for food. Normally this is not a problem for the ecosystem, because the other animals fight back. But we have become too good. We still need to get food at the cost of other animals, but we must do it in unnatural an unprecedented way.

Nature has its way of ending plagues. We may not like these ways. This is why I am interested in them.

Gerard

• John Baez says:

Gerard wrote:

The negative emotional connotation of a plague may prevent it from working as a political slogan.

I may have overreacted — after all, we’re not creating slogans here, we’re trying to understand things, and figure out what to do. But the green movement has long been criticized for an essentially negative view of the effects of humans on nature, and I’d like to avoid falling into certain traps of this sort. Later I’ll interview Thomas Fischbacher, who points out that we tend to vacillate between two extreme views:

1) humans as victorious conquerors and masters of nature,

2) humans as evil despoilers and destroyers of nature.

Both of these views are oversimplified, and we need to find more accurate and useful views. We are in fact part of nature, although a very unusual and novel part, that’s still just in its first stages of affecting the world.

Plagues happen when finally, a species really does its homework. What if a plant managed to grow very efficiently, and be very poisonous to herbivores? It might cover the earth at the cost of all other life. Why has this not already happened? Would it be bad if it did?

The final question involves ethics and is thus automatically very difficult. I will sidestep it.

More interesting to me is the question right before that: why has this not already happened? This is the sort of question I imagine scientists could actually answer.

What fascinates me is that while plants do many things to avoid getting eaten by pests, they also do many things to attract herbivores to spread their pollen and seeds. I don’t think this is a complete answer to your question, but it might be relevant. There’s more to evolution than competition: there’s also cooperation.

In my diary I once wondered why grapefruit taste good. I listed various chemicals characteristic of grapefruit, including:

Limonoids like limonin, nomilin and nomilinic acid. These give citrus peels their nice tangy scent. They have antiviral, antifungal, antibacterial and insecticidal properties which defend the fruit against pests — following the same basic principle that underlies the nice smell of pine needles and many herbs and spices. Indeed, the chemicals that give pine needles, cinnamon, cloves, ginger, camphor and mints their smell are terpenes and terpenoids — and the latter include the limonoids.

It’s fascinating to me that these chemicals, which prevent pests from eating citrus fruits and spice, make us want to eat them — and that we can benefit from their properties! So, we cultivate them and breed new varieties. It’s as if these plants and we are in the same side in the bio-battle against insects and microorganisms.

Of course, there also plants we should beware of, like sassafras — it smells great, and I used to make tea out of it as a kid, but the nice-smelling stuff, safrole, turns out to be a mild carcinogen! So, we have pick our allies wisely.

It is very interesting to look at the chemical structure of terpenes and terpenoids, and learn why they’re poisonous to insects.

On another note: it might be interesting to compare people with other species that ‘took over the world’ — like trilobites.

• John F says:

Although you may be thinking of interesting math such as predator-prey relationships, or perhaps logic such as the parasite paradox (don’t kill your host), perhaps the main scientific answer to why Earth retains biodiversity is that it has always had diverse habitats. Also the Earth is large and plants don’t move fast, so none of *them* will take over the world before evolving. The trilobites dominated in basically a single habitat, shallow warm ocean, and even then their lack of extinction evidently required considerable diversity. FWIW taxonomically trilobite success is more akin to mammal success rather than human success.

Wherever natural monocultures locally dominate, such as aspen or birch stands, the populations never are very old and are intolerant of invasive species and pathogens. Relatedly, human gut flora diversity decreases due to urbanization. Some important bowel diseases are due to attacks *on* (not by) good gut flora. One more factoid: almost all sewage treatment effectiveness measures depend upon the activity of viruses to kill bacteria.

• westy31 says:

John wrote:

More interesting to me is the question right before that: why has this not already happened? This is the sort of question I imagine scientists could actually answer.

I am glad we’re avoiding a polemic style discussion.

I wonder about this for example when I see how a field often consist of a mix of grass, clover, dandelions, and some other flowers. Apparently, although they continually compete, they stay in a perpetual balance of power. I don’t know why this is, but perhaps agriculture can learn from this; crops are usually grown as a monoculture. (hmm, clover can fix nitrogen…Maybe the other plants need clover for the nitrogen, when there is enough nitrogen, they outgrow the clover until they start suffering nitrogen starvation)

One mechanism for biodiversity I can think of is disease. If you have lots of the same species in a small space, disease will spread very efficiently. Another is temporary lack of selection pressure. In the Wikipedia article on biodiversity, they mention that biodiversity varies with time, being in a minimum after a mass extinction, and growing when the climate is stable. Third reason, species are interdependent. I remember a Darwin quote that said something like worms are extremely important. They transport material through the soil; apparently we would all die without them.

It’s as if these plants and we are in the same side in the bio-battle against insects and microorganisms.

Maybe because insects are not helping to spread the seed, they just eat the fruit. Mammals and birds eat the fruit while spreading the seeds.

Understanding these things will be important for deciding how to grow food for 9 billion people. Its not as simple as letting nature do its thing. Man intervention like irrigation and fertilisation are inevitable.

There is probably some cool maths out there too. Verhulst dynamics is just the simplest example…

Gerard

• John Baez says:

Gerard wrote:

I am glad we’re avoiding a polemic style discussion.

Me too — I prefer to figure things out than fight, and when it comes to the tough problems I’m talking about nowadays, I need all the help I can get.

I wonder about this for example when I see how a field often consist of a mix of grass, clover, dandelions, and some other flowers. Apparently, although they continually compete, they stay in a perpetual balance of power. I don’t know why this is, but perhaps agriculture can learn from this; crops are usually grown as a monoculture.

Fairly soon on This Week’s Finds I’ll be interviewing Thomas Fischbacher, who will talk about ‘permaculture‘. This is an approach to agriculture that, among other things, avoids monocultures.

I don’t know why fields have mixtures of plants they do. It would be fascinating to spend a few decades studying this.

If you’re not familiar with the concept of a ‘guild’ in ecology, you might be interested in studying it. A guild is a group of populations that compete for the same resources in a similar way. How can different members of the same guild stably coexist? I know ecologists think about this question but I don’t know what they think. I’m having trouble finding a good link, but you might try this. There is probably better material available in textbooks and journals.

It’s as if these plants and we are in the same side in the bio-battle against insects and microorganisms.

Maybe because insects are not helping to spread the seed, they just eat the fruit. Mammals and birds eat the fruit while spreading the seeds.

That must be it. Note that my grapefruit has nice flowers with nectar for the bees — it’s not opposed to insects on principle, just the ones that hurt it.

There is probably some cool maths out there too.

Definitely!

23. gowers says:

I’ve just discovered this blog, and am very pleased to see it. My attitude to climate change has been one of something close to despair (coupled with a desperate hope that the deniers and sceptics might turn out to be right for unexpected reasons). It seems to me that we face a sequence of questions of increasing abstraction, with “What should we do about climate change?” right at the bottom, and “Is there, in fact, no solution to the tragedy of the commons?” somewhere near the top.

Something like a tax that forces people to pay the real cost of the carbon they use might seem like a solution, but it creates a higher-order problem of a similar kind since you need lots of countries to agree to do it. And this in order to deal with something that many people deny exists.

What is your view about very scary scenarios where positive feedback comes into play and leads to much bigger changes than you describe? I’m referring to this kind of thing: melting permafrost releases methane, which is far worse than carbon dioxide, and this causes more permafrost to melt, and suddenly there’s nothing we can do any more about rising temperatures. (Actually, I’ve just read the link I provided and apparently methane doesn’t last as long in the atmosphere. But I still don’t like the words “positive feedback” and find it surprising that this danger doesn’t get more publicity.)

• John Baez says:

Hi, Tim! It’s great to see you here. I’d like to see a lot of really influential mathematicians and physicists get actively involved in climate and environmental issues — but for now it’s up to pipsqueaks like me to get the ball rolling.

I will be interviewing various scientists who are active on these issues. If you know any good people who’d be willing, maybe you could let me and/or them know. But probably it’s best to wait until some interviews have already appeared. I’ve got some lined up and ready to go.

My attitude to climate change has been one of something close to despair (coupled with a desperate hope that the deniers and sceptics might turn out to be right for unexpected reasons).

That was my attitude for a long time, and I’m sure it’s widely shared. But then I noticed I had a similar attitude before I started going to the dentist regularly!

I was really scared that it was too late to do anything about certain problems with my teeth — so I was scared to go to the dentist. But I was also secretly hoping that the problem wasn’t really too bad, so I could put off going to the dentist. Finally I went to the dentist and found that 1) some of the problems were irreversible, 2) most of them could still be fixed, 3) it had been silly to wait so long, but 4) it was good to have finally done something.

What is your view about very scary scenarios where positive feedback comes into play and leads to much bigger changes than you describe? I’m referring to this kind of thing: melting permafrost releases methane, which is far worse than carbon dioxide, and this causes more permafrost to melt, and suddenly there’s nothing we can do any more about rising temperatures.

I’ll get back to you (and the world) on that. I don’t think anyone knows precisely how bad this permafrost feedback mechanism is — or, for that matter, the methane in ice clathrates at the bottom of the sea. If you want to scare yourself, read about the Paleocene-Eocene Thermal Maximum and the possible role that ice clathrates played in that.

But I still don’t like the words “positive feedback” and find it surprising that this danger doesn’t get more publicity.

Yeah, me too. My first interview will be with Nathan Urban and he’ll do a rundown of the most well-understood positive feedback mechanisms. It’s important to remember that the ones we know are still outweighed by the negative feedback caused by the fact that a hot Earth radiates more energy. In other words, as far as we can tell, we’re not actually at an unstable equilibrium where a small perturbation should cause a runaway feedback loop. But nonetheless, the effect of any small perturbation is bigger than you’d naively think, thanks to various positive feedback mechanisms.

• Steve Bloom says:

We may not be at risk of any sort of runaway, although IMHO a potential rapid permafrost melt carries with it the risk of a PETM-like excursion, but let’s not forget that the equiibrium climate state associated with the amount of forcing we’ve already applied involves some considerable differences in ocean-atmosphere circulation relative to the present, and based on past experience there’s every reason to expect at least some aspects of the transition to be abrupt. A new paper discusses the tendency toward abrupt change (press release).

• Richard Séguin says:

I also have been worried about the possibility of positive feedback. Unfortunately, I think that human behavior itself can be one positive feedback pathway. In the developed world we deal with increasing heat by using air conditioning more, and since a large percentage of air conditioners (especially in North America) are ultimately driven by coal, green house gases rise even further. Where I live, in Wisconsin, we just had one of the hottest summers on record, and the local power company publicly noted the unusually high utility bills.

One way of dealing with large temperature swings is migration: if it’s too hot, travel toward the nearest pole. This is no longer a viable solution for most humans and animals. People are now tied to jobs, and the population is now so high and private property so pervasive that movement is severely constricted for them. Birds can still migrate easily, but many mammals that could have easily migrated in the past can no longer do so because of habitat loss and all of the obstacles that people have now put in their way, and of course frogs and turtles can never go anywhere very fast. Many mammals and amphibians may be screwed, but humans can and do invoke dirty technology to solve their problem in the short term.

One can speculate that in rising temperatures, increased use of air conditioning is balanced by decreased use of furnaces. I personally don’t have the information needed to determine if that is true or not, although I think I might have seen something in the press to the effect that air conditioning may be exceeding furnaces as a problem. If anyone knows the answer to this, I would like to know.

Steve Bloom’s comment referring to chaotic behavior reflects another fear of mine. This should be of interest to some dynamical systems folks. Fortunately, I fall asleep at night rather easily.

24. […] kevin on September 1st, 2010  Here’s a well-written blog post from John Baez, a mathematical physicist who is now working on less abstract things such as Climate […]

25. vorpal says:

There are 2 primary ways of helping:

1) preserving habitat
2) effectively selecting habitat to preserve

the Union of Concerned Scientists is a bunch of fools who think that technology can save the planet. This is because they are scientists. They have a hammer and thus the problem is a nail.

To the contrary, James Hansen is absolutely correct when he points out that the problem is primarily an economic one. He is right when he says the answer is not in _adding_ technology, but rather _subtracting_ resources from the human dinner plate. In fact, I was one of the first people to point this out to him. And to his credit, he has moved away from the technofix. Hanson is one of the few that understand the nature of the beast.

To be effective, environmentalists should be extremely focussed in their mission: Preserve and protect habitat. The less resources are available to people, the more chance the other creatures have of surviving.

Science can help by ensuring that the most important habitats are protected first. They need to know what needs to happen to ensure success.

In short, anything you buy for yourself hurts (yes dear, even the hybrids), any habitat you preserve helps.

• John Baez says:

I’ll let you go ahead and call the Union of Concerned Scientists ‘a bunch of fools’ just this once because:

1) you probably didn’t notice yet that insults are forbidden on this blog,

and

2) the Union of Concerned Scientists will probably not be seriously hurt by your remark.

I completely agree that the problem is primarily an economic one. I wouldn’t be surprised if the Union of Concerned Scientists agrees with that. But I don’t know if their goal is to ‘preserve habitat’. One can imagine other goals. If they have different goals, they’ll probably advocate different approaches.

It is interesting to look at their National Blueprint for a Clean Energy Economy — thanks for bringing it to my attention. They’re trying to lay out a method to:

1) Reduce annual U.S. emissions at least 80
percent from 2005 levels by 2050.

2) Constrain cumulative U.S. emissions to the
mid-range of a 2000–2050 U.S. “carbon budget”
of 165–260 gigatons CO2 equivalent.

It is difficult to summarize their strategy (since I’m just reading this stuff), but here are a few of their economic considerations:

Understanding Market Barriers to Climate Solutions

Many studies have documented market barriers to the development and use of cost-effective energy efficiency, conservation, and renewable energy solutions (see Chapters 4–6).

One major market failure is that energy prices do not include all the environmental, health, and national security costs of burning fossil fuels—which greater reliance on energy efficiency, conservation and renewable energy would avoid.

A second major market failure is “risk aversion”: the reluctance of households and businesses to invest in climate solutions that have high up-front costs but long-term financial benefits.

A third major market failure is “split incentives” between building owners and renters. Owners do not make efficiency improvements because they do not pay the utility bills. Renters will not make the up-front investment because they are unlikely to occupy the building for long. These split incentives also exist between home developers and purchasers, and in other parts of the economy.

Other market barriers include:
• Lack of information and expertise on solutions to global warming
• Lack of capital needed for up-front investments in global warming solutions
• Lack of a core infrastructure and manufacturing capacity to support increased use of renewable energy, energy efficiency, advanced vehicle technologies, and expanded mass transit

Specific policies targeted at increasing energy efficiency, conservation, and renewable energy, such as those in the Climate 2030 Blueprint, can directly address these market failures and barriers. Such policies can reduce consumers’ overall costs more than energy price signals—such as those resulting from a cap-and-trade program—alone.

• vorpal says:

As James Hansen says. All that matters is what’s left in the ground.

Efficiency simply does not help. Look at US electricity consumption over the past 30 years. Has that dropped? No. Yet electrical appliances are far far more efficient than what they were.

Price is the only thing that controls consumption, and encourages efficiency. The logic does NOT work the other way. Efficiency does not reduce consumption, in fact it _increases_ it because you are getting that much more value for your money.

My recommendation works because it entails raising the price. With less resources available, those that produce them must charge more.

Finally, as far as preserve habitat goes; isn’t this what it is all about? Species exist in a habitat (including us). If you have the habitat, then you have the species. Species preservation is the number one goal of the environmental movement, since Carson’s “Silent Spring”.

The entire “efficiency” movement is a waste of time as far as enviromentalism is concerned. Efficiency helps humans, not animals. Consumption is controlled by price, not efficiency.

Like I said, look at a plot of US consumption of electricity. Efficiency is no help.

26. vorpal says:

Here is a link to the short email I wrote to Dr Hansen and his response. Just to document.

http://tinyurl.com/2643ahc

• John Baez says:

Interesting! And the notes on the interview with Hansen are also interesting.

• Eugene says:

Your discussion with Dr Hansen strongly suggests that if the efficiency of the car fleet is improved and if, simultaneously, the cost of driving a unit of distance is kept constant or increased then the total CO2 emissions may go down.

• vorpal says:

Just the opposite. This was his position in 2006, you can see from John’s (Baez) post that Hansen’s position has changed 180 since then.

These are my policy recommendations from 2007. I have yet to see anything better.

http://tinyurl.com/277bmbq

Prof. Rutledge at Caltech read them and thought I did a good job (3 years ago). Btw: Prof. Rutledge is featured in this month’s Scientific American (Sept 2010).

27. […] from: This Week's Finds (Week 301) « Azimuth Share and […]

28. Al Tekhasski says:

I really cannot understand how a scientist of such caliber as J.Baez can put his signature below this standard catastrophic AGW propaganda as this article (“week 301”). For starters, here are few standard points you need to address:

(a) Carbon “residence time” has nothing to do with anything. Any normal scientist understands that, given enormous diurnal magnitudes of local natural CO2 fluxes, the “lifetime” of CO2 is about one (!!!) day;

(b) Relationship of atmospheric CO2 concentration to “global temperature” is a pure speculation based on crude spectrally under-resolved calculations of OLR under unrealistic atmospheric conditions and using a mistaken procedure for averaging. There is no experimental confirmation of this estimation of 3.7W/m2 “radiative forcing” per CO2 doubling;

(c) Climate sensitivity derived from variations of CO2 in ice core records contradicts to sensitivity derived from modern instrumental records by an order of magnitude.

I think this should be enough to retract this entire article (“week 301”).

• John Baez says:

Let’s cut the rhetoric and focus on the science. And let’s tackle one of your points at a time — talking about too many things at once gets confusing.

(a) Carbon “residence time” has nothing to do with anything. Any normal scientist understands that, given enormous diurnal magnitudes of local natural CO2 fluxes, the “lifetime” of CO2 is about one (!!!) day;

As I’m sure you’re aware, saying something does not make it so. Please give a reference for your claim here, preferably from a credible scientific source.

Also: please make it clear what you mean by saying that the “lifetime” of CO2 is about one day.

I didn’t actually mention “residence time” in week301, so I’m not sure why you bring it up only to dismiss it. But I think it’s important to make sure we understand what we mean by that term, as well as the ambiguous term “lifetime”. The details are crucial here.

Individual carbon dioxide molecules enter and leave the atmosphere quite quickly. But if you add a gigaton of CO2 to the atmosphere, it takes considerably longer for the amount of CO2 in the atmosphere to return to its original value.

This is easy to understand: it’s just like how on a subway, individual passengers may enter and leave quickly, but the overall number of people on the subway changes more slowly.

The first, shorter timescale is sometimes called the “residence time” or “turnover time”.

The United States Environmental Protection Agency gives this definition:

Residence Time: The average time spent in a reservoir by an individual atom or molecule. With respect to greenhouse gases, residence time usually refers to how long a particular molecule remains in the atmosphere.

The glossary of Climate Change 2007: Working Group I: The Physical Science Basis gives a more precise definition for what they call “turnover time”:

Turnover time (T) (also called global atmospheric lifetime) is the ratio of the mass M of a reservoir (e.g., a gaseous compound in the atmosphere) and the total rate of removal S from the reservoir: T = M / S.

With this definition, the turnover time of CO2 in the Earth’s atmosphere is roughly 4 years, because there’s roughly 750 gigatons of carbon in the atmosphere, and roughly 200 gigatons flow into and out of the atmosphere each year.

On the other hand, we have various concepts of ‘lifetime’. The EPA gives this definition:

The lifetime of a greenhouse gas refers to the approximate amount of time it would take for the anthropogenic increment to an atmospheric pollutant concentration to return to its natural level (assuming emissions cease) as a result of either being converted to another chemical compound or being taken out of the atmosphere via a sink. This time depends on the pollutant’s sources and sinks as well as its reactivity. The lifetime of a pollutant is often considered in conjunction with the mixing of pollutants in the atmosphere; a long lifetime will allow the pollutant to mix throughout the atmosphere. Average lifetimes can vary from about a week (sulfate aerosols) to more than a century (chlorofluorocarbons (CFCs), carbon dioxide).

(Emphasis mine.)

Of course the return to original levels is an asymptotic process so this definition is approximate, as they note. The IPCC glossary is again more precise:

Lifetime: Lifetime is a general term used for various time scales characterising the rate of processes affecting the concentration of trace gases. The following lifetimes may be distinguished:

Turnover time (T) (also called global atmospheric lifetime) is the ratio of the mass M of a reservoir (e.g., a gaseous compound in the atmosphere) and the total rate of removal S from the reservoir: T = M / S. For each removal process, separate turnover times can be defined. In soil carbon biology, this is referred to as Mean Residence Time.

Adjustment time or response time (Ta) is the time scale characterising the decay of an instantaneous pulse input into the reservoir. The term adjustment time is also used to characterise the adjustment of the mass of a reservoir following a step change in the source strength. Half-life or decay constant is used to quantify a first-order exponential decay process. See “response time” for a different definition pertinent to climate variations.

The term lifetime is sometimes used, for simplicity, as a surrogate for adjustment time.

In simple cases, where the global removal of the compound is directly proportional to the total mass of the reservoir, the adjustment time equals the turnover time: T = Ta. An example is CFC-11, which is removed from the atmosphere only by photochemical processes in the stratosphere. In more complicated cases, where several reservoirs are involved or where the removal is not proportional to the total mass, the equality T = Ta no longer holds. Carbon dioxide (CO2) is an extreme example. Its turnover time is only about four years because of the rapid exchange between the atmosphere and the ocean and terrestrial biota. However, a large part of that CO2 is returned to the atmosphere within a few years. Thus, the adjustment time of CO2 in the atmosphere is actually determined by the rate of removal of carbon from the surface layer of the oceans into its deeper layers. Although an approximate value of 100 years may be given for the adjustment time of CO2 in the atmosphere, the actual adjustment is faster initially and slower later on. In the case of methane (CH4), the adjustment time is different from the turnover time because the removal is mainly through a chemical reaction with the hydroxyl radical OH, the concentration of which itself depends on the CH4 concentration. Therefore, the CH4 removal rate S is not proportional to its total mass M.

(My emphasis.)

It is important to note that if you add a gigaton of CO2 to the atmosphere, several different processes with different time scales are involved in the return of the CO2 level to its original value: it’s not just an exponential decay process. So, interpreting “lifetime” as “half-life” is not really accurate.

Here are some references that have the advantage of being free online. Perhaps experts here can provide more:

Carbon is forever, Nature Reports Climate Change, 20 November 2008. (Has a useful bibliography of recent literature.)

• TML Wigley, Balancing the carbon budget. Implications for projections of future carbon dioxide concentration changes, Tellus 45B (1993), 409-425.

The Global Carbon Cycle, SCOPE Vol 13, edited by B. Bolin, ET Degens, S Kempe and P. Ketner, John Wiley & Sons; 1979. (Old but useful.)

So, please state precisely what you mean by ““lifetime” of CO2 is about one (!!!) day”, and provide some credible evidence for this claim.

29. Al Tekhasski says:

I entirely agree to cut the rhetoric, especially the fuzzy IPCC glossary. However, it is difficult to make precise statements in this field. It is quite obvious that perturbations of state trajectory of such complex nonlinear system as Earth cannot be adequately approximated by a simple fixed point topology, especially when we are dealing with averaging of chaotic dynamics on a 2D torus. Before being able to operate with global averages (“750GT”, “7GT/year”), one needs to begin with underlying instant dynamics of CO2 exchanges, because the formal averaging procedure of turbulent continuous media does not yield a closed set of equations.

Now, to illustrate the scale of real CO2 processes, I suggest to stop thinking about bulk atmosphere, and consider the so-called “Atmospheric Boundary Layer”(ABL), where the most meteorological and biological activity occurs, see
http://lightning.sbs.ohio-state.edu/geo622/622_lectures.htm
Any infusion of carbon must pass through this layer first before being “integrated” by bulk atmosphere. Let’s consider the amount of local mass of carbon in this layer and its variations.

This ABL is 100m to 3000m high. Generously assuming the lowest 100m, this layer contains about 1% of air mass, and therefore contains about 7.5GT of carbon, or 7.5E+12 kg. Considering that Earth surface is 5.1E+08 km2, it gives about 1.5E+04 kg of carbon per each km2 of the boundary layer.

Now let’s estimate daily changes in amount of carbon in this layer of air using observational data. On waters, the following source,
http://www.co2.ulg.ac.be/pub/Frankignoulle_et_al_2003.pdf ,
says that the day-night variation of CO2 is from 375 to 650 ppm. On land, according to http://meteo.lcd.lu/papers/co2_patterns/co2_patterns.html , the typical observed variations are from 380 to 480ppm. Obviously, as expected, these numbers fluctuate with wind and who knows what else, but fluctuate substantially. These data show that every day the local concentration of CO2 (over 1km2 area) varies by about 30% on average.

This means that every morning the increase in local carbon storage is about 4500kg per km2 of surface area. Then, every afternoon, nearly 4500kg are consumed back by natural processes. This cycling up and down of 1/3 of entire carbon content of ABL happens every day.

That’s why I’d say that CO2 “turnover time” is of the order of few days, not years.

Now, the global man-made emissions of carbon are estimated as 7GT/year. This amounts to 38kg of carbon per km2 per day. Therefore, as we see, man introduces about 38kg into local afternoon sink of 4500kg. This is less than 1%. One might even wonder if this minuscule amount can change anything at all in the integral sense.

Furthermore, according to my concern (b), all this CO2 business seems to be largely irrelevant to climate dynamics.

• John Baez says:

Al wrote:

It is quite obvious that perturbations of state trajectory of such complex nonlinear system as Earth cannot be adequately approximated by a simple fixed point topology, especially when we are dealing with averaging of chaotic dynamics on a 2D torus.

For the nonmathematicians reading this, let me translate. You are saying that

1) the weather doesn’t settle down to a constant, unchanging state; small changes can have a big effect,

and

2) the earth is doughnut-shaped.

I don’t wish to discuss these points, though I can’t resist registering doubts about the second. As I said, it gets confusing to talk about lots of things at once. I want to focus on your claim that:

CO2 “turnover time” is of the order of few days, not years.

and settle it if possible, or agree to disagree. Then we can go on to another claim, and so on. That’s how real progress in understanding is made.

So: we are talking about “turnover time”: the average time that a CO2 molecule stays in the air. We are not talking about what the IPCC call the “adustment time”: the approximate time it takes for an amount of CO2 added to the air to go away. It’s the adjustment time that matters for global warming, not the turnover time. So, your claim has only indirect relevance to global warming.

If we were trying to understand global warming, we’d need to focus attention on the adjustment time. We’re not. But that’s okay: it’s good to think about physics for its own sake.

So, let’s do it!

As far as I can tell, you’re claiming that the atmosphere has a lower layer, 100 to 3000 meters high. And you wish us to focus attention on the turnover time for molecules in this lower layer. You do not want to discuss the turnover time for the whole atmosphere.

This is an interesting project. Let me note two points:

2) A CO2 molecule in this lower layer can leave or enter either from above, or from below. That is, it can either move into or out of the atmosphere further up, or enter or leave the ocean or land (including plants on land, etc.). To analyze the situation we need to study both possibilities.

3) This lower layer seems extremely ill-defined. There is, after all, no “ceiling” that separates it from the air above. We can arbitrary specify some height for the lower layer, and our answer will depend on this height. I suspect that the turnover time will become shorter as we make the height lower. Why? Both because CO2 molecules will more quickly be absorbed by the ocean or land below, and because they will more quickly rise to higher layers!

So, for example, if we define the lower layer to be one centimeter high, the turnover time for this layer will probably be much less than a day. If we define it to be one millimeter high, it could be on the order of a minute.

Are you suggesting that there’s some specific height — possibly varying with location — that’s particularly interesting to study? If so, how do we define this height? If not, let’s just pick one arbitrarily and proceed.

Since you haven’t cited any literature on this subject, does that mean this idea is an invention of your own? If you’re serious about it, you should do a literature search to avoid wasting a lot of time “reinventing the wheel”. Do you have access to a university library?

• Steve Bloom says:

Aha, wrong — he clearly specified a *2D* torus, so no doughnut! :)

• Al Tekhasski says:

John:
(1) Since the entire system is forced with two externally imposed frequencies, its PHASE SPACE is a direct product of 2D torus and the whatever else (rather multidimensional subspace) is left. The Earth itself is obviously nearly spherical at this level of accuracy :-). I hope I don’t need to introduce and elaborate on the concept of state space of dynamical systems, although it is usually a deep post-graduate topic.

(2) I am not claiming that Earth atmosphere has this boundary layer; this is obvious and well known (for some people) fact, and I gave a reference to this important phenomenon.

(3) Yes, the ABL is a complicated spatio-temporal object. Properties of boundary layers are intriguing and were subject of massive scientific research in mechanics of continuous media. And no, unfortunately, there is no specific scale which is particularly “interesting”: it is known from basic theory of turbulence that there is no single characteristic scale but rather a continuous spectrum of cascade of scales, both into low and high wavenumbers. This is one of reasons why it is not possible to clearly separate weather from climate, which is confusing for most climatards.

(3a) Yes, it is possible to define smaller parcels of the boundary layer, and this is exactly where physical processes occur that define the actual CO2 production and consumption: consider a typical tree leaf as an elementary exchanger.

(3b) If you want to have an example of a millimeter-scale surface processes that define the rate of CO2 exchange, consider a sea-air interface, where a microscopic surface-tension driven convection occurs, all strongly depends on “cold” or “warm bias” (aka the sign of temperature difference between sea and air) and local wind speed.

(4) I am not reinventing any new wheel. I am just pointing to a glaring blank in climatology. As Ray Pierrehumbert wrote in his book (that used to be available online), “volumes are written on this subject”. I assume that it is a common knowledge for a reasonably educated scientist, although I do realize that the theory of motion of continuous media is at the opposite end if physics to the quantum field theory.

However, I would like to claim the idea of comparing magnitudes of localized natural CO2 fluxes with man-made contribution as mine, although it is quite possible that independently and somewhat earlier similar ideas had already visited other inquiring minds.

• bane says:

FWIW, in trying to find the “constructivist” work from which Al is working, I tried to look at any citations. One of the names cited was Pierrehumbert, but reading the pdfs available on his web-page I come across

Pierrehumbert RT 2006: Climate change: A catastrophe in slow-motion. Chicago Journal of International Law, 6, 573-596

wjere he makes statements roughly co-inciding with John’s account how the volume of carbon dioxide in various parts of the atmosphere changes. So assuming his no longer available book didn’t do a volte face on the issue, it appears Pierrehumbert’s own contribution to the “volumes written on the subject”, even if unread, don’t support Al’s point.

• John Baez says:

Al wrote:

The Earth itself is obviously nearly spherical at this level of accuracy :-).

Okay, good: while the ‘doughnut earth’ theory has its charms, I don’t think it’ll ever get much of a market share compared to the ’round earth’ and ‘flat earth’ theories.

Steve wrote:

Aha, wrong — he clearly specified a *2D* torus, so no doughnut! :)

Well, mathematicians call the surface of a doughnut a 2d torus, even if it’s embedded in 3d space in the usual way, like this:

A real doughnut with the dough inside, we call a ‘solid torus’.

Al wrote:

… the theory of motion of continuous media is at the opposite end of physics to the quantum field theory.

I don’t feel that way: they’re both field theories, and I got tenure based on my work on classical field theory. But the Navier-Stokes equations were never my favorite thing: I wasted my youth thinking about nonlinear wave equations like the Yang-Mills equations and the φ4 theory. So I never spent much time thinking about boundary layers — though of course I’ve known about them since I was a kid, just from playing in creeks, reading physics books, and wondering why golf balls have dimples.

So, we seem to agree that the concept of ‘atmospheric boundary layer’, while important, is not sharply defined: in that Powerpoint presentation you referred to, from Jialin Lin’s class on Boundary Layer Climatology, he says:

Definition of the atmospheric boundary layer: that part of the troposphere that is directly influenced by the presence of the Earth's surface and responds to surface forcings with a time scale of about an hour or less. Scale: variable, typically between 100 meters and 3 kilometers deep.

But it seems clear that the time scale of ‘one hour’ is a bit arbitrary: as you say, there’s “no single characteristic scale” but rather a continuous spectrum of time and length scales at work here.

So, we should just accept this fact and consider a concept of turnover time that depends on the thickness of the slice of atmosphere we happen to be considering. In the limit where this slice gets so thick as to include the whole atmosphere, this time should approach 3-4 years, since then the only way for a molecule of CO2 to leave this slice is to go into the ocean or ‘land’ (which I’m always using to include plants, animals, etc.). But for thinner layers it will be less.

And as you note, the turnover time will probably also depend a lot on where we are. You mentioned the paper by Frankignoulle et al. They saw the CO2 vary daily from 385 to 750 ppm in a mangrove swamp, while remaining close to constant in the nearby open ocean!

It would be nice to study this complicated business, even though its relevance to global warming eludes me, since human-made CO2 still goes into the upper atmosphere, where it contributes to the greenhouse effect. (Or are you claiming otherwise?)

But, to study this, I would start by digging into the published literature…

I am not reinventing any new wheel. I am just pointing to a glaring blank in climatology. As Ray Pierrehumbert wrote in his book (that used to be available online), “volumes are written on this subject”.

I’m a bit confused. First, it’s impossible to reinvent a new wheel — the problem is reinventing an old one. But more importantly, if “volumes are written on this subject” then how could it be a “glaring blank”?

Are you saying that specialists in weather and climate haven’t thought about boundary layer phenomena even thought they’re well-known in physics? That seems hard to believe. After all, you pointed out that Jialin Lin is teaching a class on Boundary Layer Climatology at Ohio State, and his specialties include “global climate modeling”.

30. Al Tekhasski says:

John, let’s drop your mockery about “doughnut earth”. You are obviously not up to speed with geometrical concepts in differential equations and nonlinear dynamics in general. I suggest to start with introductory book “Ordinary Differential Equations” by V.I.Arnold (ISBN 962-430-026-7, an edition for middle Asia) before trying to understand applications to N-S equations. This book is miles above the heads of contemporary climatards, but you should digest it in a couple of weeks given your background. Then look at ISBN 962-430-029-1, and more special literature.

I also have no intent to argue semantics about new or old wheels, or glaring or dull omissions. It is obvious that while volumes are written, they are not necessarily being read by people in question. And if read, it is not necessary being understood.

Regarding that the boundary layer “is not sharply defined”, its imprecise definition does not preclude all important gas exchanges to be confined to small local areas along very complicated surfaces, where CO2 fluxes exceed man-made contribution 100-fold. To attribute all bulk increases in CO2 to men, one needs to assume perfect “balance” between natural CO2 producers and consumers, which is not the case: rotting soil in Amazon does not know how much leaves will grow this season in Siberia and Canada.

Regarding your statement that “human-made CO2 still goes into the upper atmosphere, where it contributes to the greenhouse effect”, then yes, I will argue that this contribution is likely highly overstated.

• John Baez says:

Sorry to annoy you with the “doughnut earth” jokes, Al. Doubtless miffed, you wrote:

You are obviously not up to speed with geometrical concepts in differential equations and nonlinear dynamics in general.

If I made a mistake in something I said, please point it out and correct it.

It is obvious that while volumes are written, they are not necessarily being read by people in question. And if read, it is not necessary being understood.

Okay, so you’re claiming that climate scientists are making big mistakes because they don’t understand boundary layer effects well enough, even though other people do.

At this point I’m willing to turn my attention to that issue, because I think we see eye-to-eye on some of the preliminaries. But let me just recap the conversation so far, to make sure.

At first you said the “lifetime” of CO2 is on the order of days. I pointed out that “lifetime” can mean several different things.

I think we’ve got that clarified now: you’re saying that the turnover time of CO2 residing in some layer of the Earth’s atmosphere near the Earth’s surface is on the order of days.

In other words: after a period of days, an average molecule in this layer will either be absorbed by the ocean or land, or drift up to higher layers.

Good. That makes sense. Indeed it’s bound to be true if we choose the right thickness for this layer — since the thinner we define this layer to be, the shorter the turnover time, while if it’s thick enough, the time is about 3-4 years.

Furthermore, you seem to be claiming that the right thickness is about 100 – 3000 meters high. I don’t know if that’s true. To resolve this question, maybe one could measure the daily variation of CO2 concentrations at various altitudes, with the help of an airplane. Someone should have tried that already, but I don’t know if they have.

Anyway, now let’s move on to the possible relevance of these ideas to global warming.

I have two questions here:

1) First, the issue of the ‘adjustment time’: the approximately defined time it takes for a bunch of CO2 dumped into the atmosphere to ‘go away’. Do you believe that the existence of a thin layer with short turnover time implies that the adjustment time is also short?

That’s what I thought you were saying, at first: people often claim that. But now I think you meant something else, namely:

2) Are you claiming that if there’s a thin boundary layer such that natural CO2 fluxes in and out of this layer greatly exceed man-made ones, the man-made contributions will not ‘add up’ to create a gradual increase in CO2 concentrations?

That seems to be the idea here:

Regarding that the boundary layer “is not sharply defined”, its imprecise definition does not preclude all important gas exchanges to be confined to small local areas along very complicated surfaces, where CO2 fluxes exceed man-made contribution 100-fold. To attribute all bulk increases in CO2 to men, one needs to assume perfect “balance” between natural CO2 producers and consumers, which is not the case: rotting soil in Amazon does not know how much leaves will grow this season in Siberia and Canada.

I’d love answers to questions 1) and 2).

• Al Tekhasski says:

John wrote:
“If I made a mistake in something I said, please point it out and correct it.”

Yes, you made a mistake of confusing physical geometry of system with geometry of attractor in its phase space.

You wrote: “so you’re claiming that climate scientists are making big mistakes because they don’t understand boundary layer effects well enough, even though other people do.”

No, I did not claim such thing. No one “understands” boundary layers well. Climatology makes a mistake when it takes approximate parametrizations of boundary layers, but then treat them as absolute truth and extends them beyond established limits of applicability.

Let’s recoup our current standings. You seem to admit that there is an intensive boundary layer that determines spatio-temporal fluctuations of CO2 sources and sinks. The magnitude of these fluctuations is very substantial. All processes (including man-made) occur inside this boundary layer.

Now, what is the mechanism of “adding-up” of “Boundary Layer CO2” to “Bulk CO2” (the one measured at Mauna Loa)? This mechanism is known as “intermittency” and “entrainments”. [Google{boundary layer entrainment} gives 343,000 hits]

These processes are highly turbulent and unpredictable. Simply speaking, when peak of CO2 is reached at some point in day, some fraction of it gets carried away into the bulk. I agree that once this CO2 excess enters the relatively isolated bulk of atmosphere, it stays there for long time.

Likewise, when CO2 gets depleted in some area of boundary layer, entrainments of fresh bulk CO2 supply the influx. Without global CO2 sources the entire CO2 air content could be consumed by photosynthesis very fast, in one season I guess, or even faster.

Now, you seem to agree that the man-made contribution to local magnitudes of these flux fluctuations is small, about 1%. They should be considered as negligible in any reasonable physical theory. It does not seem very logical to conclude that the negligible effect determines all increase in atmospheric CO2, unless the first order processes cancel each other precisely. As I argued, it is hard to believe, given substantial distances (in time and space) between producers and consumers, and correspondingly weak cross-coupling. Of course, soils “remember” the amount of leaves grown couple years back to some degree, so the actual system is a non-autonomous system with delays, which is known for not easy mathematical treatment. Therefore, I remain very skeptical about CO2 projections based on averaged box models.

And again, there are indications that all this CO2 fuss is unimportant for the problem of global warming.

• John Baez says:

Al wrote:

Now, you seem to agree that the man-made contribution to local magnitudes of these flux fluctuations is small, about 1%.

Well, let’s see. I could do some reading but I’m pretty busy right now, so I’ll just note that NASA estimates:

• 5.5 gigatons of carbon per year goes into the atmosphere from fossil fuels and cement production
• 1.6 gigatons of carbon per year goes into the atmosphere from change in land use, e.g. deforestation.

while natural causes put in about:

• 60 gigatons C / year from vegetation
• 60 gigatons C / year from soils
• 90 gigatons C / year from the oceans

Of course carbon also goes out of the atmosphere into vegetation, soils and oceans, but I’m trying to see what percentage of carbon flowing in comes from human causes.

I’m getting 7.1. gigatons/year from human causes and 210 gigatons/year from natural causes. That’s 3.4%.

So, a lot more than 1%, but still within an order of magnitude of that guess.

They should be considered as negligible in any reasonable physical theory.

Why? This is what I don’t get. While 3.4% may seem small, I don’t see why it’s ‘negligible’. Small amounts can add up over time. The complicated boundary layer issues you raise might prevent this from happening, but you haven’t said why they will.

I’ve been trying to find a nice example to illustrate my point. Here’s is the best one I can think of so far — imperfect, but maybe it gets the point across.

Consider the house edge in various casino games. The ‘house edge’ or ‘vigorish’ is the percentage of money the casino makes on average each time you play that game. Apparently the house edge is lowest for craps (a dice game), namely 0.6%. You might say that this percentage is ‘negligible’ — but clearly it’s not, because casinos find it profitable to run this game! The customers, distracted by the random fluctuations of wins and losses, may not notice that overall, on average, their money is gradually going to the casino. But it is.

Similarly, I think we agree that the flow of carbon dioxide in and out of the boundary layer is a complicated and unpredictable process. You described it nicely:

These processes are highly turbulent and unpredictable. Simply speaking, when peak of CO2 is reached at some point in day, some fraction of it gets carried away into the bulk. I agree that once this CO2 excess enters the relatively isolated bulk of atmosphere, it stays there for long time.

We can think of this process as a bit similar to a casino game where the upper atmosphere gains and loses CO2 from the lower atmosphere in an erratic manner. But if the ‘house odds favor the casino’, I’d expect the upper atmosphere to keep gaining CO2 on average.

Again, the analogy is imperfect. It’s easy to find flaws in it.

But my real point is this: you haven’t said why you think the human-caused influx of carbon dioxide should have a negligible effect. You’ve simply asserted that the large random fluctuations will make a 1% effect, or 3.4% effect, count as ‘negligible’. But the carbon dioxide concentration of the atmosphere is going up 0.5% each year, now. That’s the effect we’re trying to understand. So it’s not clear that discounting effects at the 1% level is admissible.

Without global CO2 sources the entire CO2 air content could be consumed by photosynthesis very fast, in one season I guess, or even faster.

Maybe I’m mixed up, but that doesn’t sound quite right. According to NASA, there are about 750 gigatons of CO2 in the atmosphere, while land plants absorb about 120 gigatons per year, and marine plants absorb about 50.

On the positive side, I agree that boundary layer effects, turbulence and entrainment are likely to be important in understanding how CO2 spreads through the atmosphere. A simple “diffusive” model would be really oversimplified.

• Al Tekhasski says:

John,
Your (or NASA) example deals with globally averaged numbers. The actual physical processes occur on much smaller scales, as I illustrated for the worst case of 100m. For more realistic (average) height of ABL, the percentage of man-made influx may go down to 0.1%. Of course, all depends on variations in “effective” CO2 boundary layer, which I don’t know, and doubt if anyone else does. It is hard to measure.

But you are correct, this does not preclude this stuff from accumulation, theoretically. However, I already explained my reason: it could happen only if first order processes practically cancel each other with the same accuracy. As I said, I cannot imagine how daily fluctuations of photosynthesis (that depends on instant insolation) match respiration to that degree, and how Amazon forests know now much CO2 will sink in Northern Atlantic.

Your casino example is also a typical AGW talking point, and is wrong. The 0.6% accumulation comes from knowing exact dice probabilities, which are time-independent and symmetrical. Probabilities of weather attractor are not known to anyone, not in short term, and not on 100,000 year scale.

Regarding my estimation of CO2 depletion time, here are some numbers. As we saw from the local ABL example, the _observed_ sink of CO2 is 4500kg of carbon per km2 per day. This amounts to global 2GT daily. Or the 750GT will be consumed in 375 days. But, accounting for diversity of lands and waters, it might boil down to the NASA estimates of 3 years. So, the 3 years seems to be a very realistic estimation of atmospheric relaxation time, which is supported by observations of effects of Pinatubo eruption. So, not “hundreds of years”, which is a typical AGW catastrophism.

[P.S. Did you get Arnold’s books?]

• John Baez says:

Al wrote:

Your (or NASA) example deals with globally averaged numbers. The actual physical processes occur on much smaller scales, as I illustrated for the worst case of 100m. For more realistic (average) height of ABL, the percentage of man-made influx may go down to 0.1%.

Yeah, I kind of figured some sort of averaging could be involved in those NASA numbers. For example, plants take in CO2 every day but also put out some CO2 at night due to cellular respiration. I don’t know for sure, but I imagine they don’t separately estimate both those quantities and subtract them, because the difference is probably easier to estimate. Right?

But you are correct, this does not preclude this stuff from accumulation, theoretically. However, I already explained my reason: it could happen only if first order processes practically cancel each other with the same accuracy.

Why? Why do you think human-produced CO2 can accumulate in the atmosphere only if the ‘first order’ processes practically cancel each other? That’s what I want to know.

Your casino example is also a typical AGW talking point, and is wrong.

Oh shucks, I made it up myself — I didn’t know it was a ‘standard talking point’. Guess I reinvented an old wheel.

But as I already said, I know it’s a flawed analogy. It wasn’t supposed to prove anything: just illustrate how small effects can be hidden behind large fluctuations at short distance or time scales, yet add up and become important at large scales.

Now, you’re claiming this effect can’t happen with carbon dioxide. You’re saying human-created CO2 can’t gradually build up unless some unlikely cancellation of ‘first order’ processes occurs. I think I understand this claim.

Now I want to know: why do you believe this? I can’t move on to other issues until I understand your logic in detail.

[P.S. Did you get Arnold’s books?]

I’ve looked at those books before, back when I was interested in dynamical systems. But I’ve actually spent more time with his Mathematical Methods of Classical Mechanics, since I used it to teach a class. Most of my limited knowledge of general (non-Hamiltonian) dynamical systems comes from Abraham and Marsden’s tome.

I’m sure it would it be great to reread those books, because Arnold is a great writer and a great mathematician. Even if I theoretically know that stuff, it would be great to learn it again. But unfortunately I have limited time, so most of my technical reading these days must be related to my job. So: optical lattices, the Hubbard model, tensor network states, Lindbladian mechanics — that’s the stuff I need to read about. And I really don’t get the feeling that Arnold’s books are what I need to understand your theories about carbon dioxide and atmospheric boundary layers. It would probably make more sense for me to read about carbon dioxide and atmospheric boundary layers!

• Nathan Urban says:

John,

While I’m not really interested debating with someone who regularly refers to people as “climatards” (isn’t that against your blog policy?), you might appreciate knowing that there are meteorologists who are expert in both atmospheric boundary layer physics and the carbon cycle. For example, my Penn State meteorology collaborator Ken Davis, or Scott Denning at Colorado State. You could poke around their publication lists to see if they have any review articles on the subject, if you’d like to know more about carbon fluxes in the ABL.

• Al Tekhasski says:

Nathan, I was intrigued by your remark about expertise of your collaborators in boundary layer effects, and took a peek at your publications. In particular, I found formula (8) in your recent submitted work, “Probabilistic Hindcast … model”. The text says that

“The uptake of heat into the interior ocean is governed
by a one-dimensional diffusion equation, … (8)”

Are you familiar with the existence of substantial turbulent convective mixing in the upper layer of oceans, such that the diffusion model is a very poor approximation of heat transport? Or are you of a typical climatological opinion that “we do not have any better model, so it must be good enough”?

Also, you calibrate your model to [allegedly] known radiative forcings from GH gases for 1850-2009 (mostly CO2 as I understand). Why you are so sure that there were no other (and substantially stronger) radiative forcings during that period? It is known from recent observations [1] that global decrease in cloud cover (from 70% to 64%) has led to 2% albedo decrease from 1985 to 1998 (from 0.319 to 0.297). It is also known that radiation imbalance from 1.4% change in low cloud cover [2] exceeds the entire [alleged] effect of full CO2 doubling. Alternatively, the observed 2% albedo decrease over 1.5 decade has an equivalent of 7 (seven!!!) CO2 doubling, or two orders of magnitude stronger than historical CO2 “forcing”. How can you be sure that this kind of overwhelming radiation balance changes did not occur in the past (calibration) period?

[1] Earthshine Project http://www.iac.es/galeria/epalle/reprints/Palle_etal_EOS_2006.pdf
[2] model http://forecast.uchicago.edu/Projects/full_spectrum.html

• John Baez says:

Nathan wrote:

While I’m not really interested debating with someone who regularly refers to people as “climatards” (isn’t that against your blog policy?), you might appreciate knowing that there are meteorologists who are expert in both atmospheric boundary layer physics and the carbon cycle.

At first I thought Al Tekhasski was using “climatard” to mean something like “someone who studies climate”. Sorta like “Lombard”. Only later did I realize it might be an insult formed by blending “climate” and “retard”. But it seemed so lame that I couldn’t really believe it until now. In the future posts using that insult — or, of course, others — will be deleted.

I would like to learn more about climate fluxes in the atmospheric boundary layer (ABL), so thanks. So far I don’t understand Tekhasski’s logic for why he thinks ABL effects prevent CO2 from accumulating in the upper atmosphere unless “first order processes practically cancel each other”. Have you ever heard this claim before? You don’t need to debate him, just talk to me.

• Steve Bloom says:

Yeah, I’ve heard it before. Of course the basic answer is that the wind blows and convection happens, mixing surface CO2 upwards pretty quickly. That aside, given the consistent measurements at Mauna Loa and elsewhere, we know that whatever happens at the surface, CO2 has been increasing inexorably and that given isotope analyses the increase is anthropogenic. Of course Al will happily argue all of that with you from his understanding of first principles, without resorting to the literature (since one of his premises is that it’s all wrong).

• Nathan Urban says:

John,

For some reason your comment below didn’t have a “Reply” link, so I couldn’t respond to it, so I’m replying to my own comment.

You wrote: “So far I don’t understand Tekhasski’s logic for why he thinks ABL effects prevent CO2 from accumulating in the upper atmosphere unless “first order processes practically cancel each other”. Have you ever heard this claim before?”

I’ve heard many variants of “Anthropogenic CO2 sources are small compared to natural sources, therefore they are negligible”. I haven’t heard the version where this negligibility requires cancellation of first order processes.

Of course, there is practical cancellation of first order processes, which is why CO2 only fluctuates by a few ppm during the seasonal cycle, why CO2 was so stable during the Holocene interglacial, and only varied by ~100 ppm even between glacial-interglacial transitions.

However, cancellation of natural sources and sinks has nothing to do with whether increasing a source will tend to increase the CO2 content of the atmosphere. Of course it will. Maybe it will be a small increase superimposed on a large natural variability, but it will, in general, be an increase. And, as per above, the natural variability in the net natural source-sink is not nearly as large as the increase in the anthropogenic source.

• John Baez says:

Thanks for the reply, Nathan. That’s what I thought. So, until we hear back from Al Tekhasski, I’ll have to conclude that his first claim:

Any normal scientist understands that, given enormous diurnal magnitudes of local natural CO2 fluxes, the “lifetime” of CO2 is about one (!!!) day

is based on a theory that is simply wrong. (There is also the data to consider, but our discussion hadn’t gotten into that yet.)

For some reason your comment below didn’t have a “Reply” link, so I couldn’t respond to it…

You’ll note that with the nested comments in this blog, each comment is more skinny than the comment it’s commenting on. After four layers of comments they get ridiculously skinny so no fifth level of comments is allowed.

So, you’re supposed to do what you actually did: don’t reply to the comment you’re commenting on, but to the comment it is commenting on.

In fact I often use this trick even when it’s not strictly necessary, to keep my comment from getting annoyingly skinny.

If someone knows how to edit the CSS for WordPress blogs to improve the layout of comments, please let me know.

• bane says:

One quick and dirty option might be to decrease both the indent-per-level and drop the margins around comments. I’m not sure this will work but you might try this (copied and modified from elsewhere on the net)

ol.commentlist li.comment ul.children li.depth-2 { border-left:2px; margin:0 0 0em 0em; }
ol.commentlist li.comment ul.children li.depth-3 { border-left:2px; margin:0 0 0em 0em; }
ol.commentlist li.comment ul.children li.depth-4 { border-left:2px; margin:0 0 0em 0em; }

I’ve no idea why this does whatever it does, but it might conceivably work.

• Al Tekhasski says:

John, There is indeed the “cancellation” of global fluxes, just by virtue of existence of relatively stable global climate attractor. Most convincing evidence for relationship between atmosphere and man-made emissions is the CO2-O2 diagram

based on estimations of changes in oxygen. However, allow me to remain skeptical about the exact magnitude of “net fluxes” that were “computed” from only four (!) spots on otherwise spacious and highly naturally variable planet.

Although my “one day” estimation for residence time was a bit too low :-), your references to hundreds and millions of years are clearly absurd. The only right thought in your environmental essay is about dangers of overpopulation.

And BTW it is very true that Arnold WAS a great writer and a great mathematician.

• John Baez says:

But you are correct, this does not preclude this stuff from accumulation, theoretically. However, I already explained my reason: it could happen only if first order processes practically cancel each other with the same accuracy.

Why? Why do you think human-produced CO2 can accumulate in the atmosphere only if the ‘first order’ processes practically cancel each other?

• Al Tekhasski says:

John, why do you keep your questioning? If the natural fluxes do not practically cancel each other (as the expert Nathan told you so), and man-made CO2 is just 1/100th of magnitudes of local/seasonal fluxes, would not that mean that all global millennial variations are quite natural, and the human input may not matter in neither way?

But I see we are running circles, unless you have a good mathematical description of all natural-seasonal-average variability.

• John Baez says:

Al wrote:

John, why do you keep your questioning?

(a) Carbon “residence time” has nothing to do with anything. Any normal scientist understands that, given enormous diurnal magnitudes of local natural CO2 fluxes, the “lifetime” of CO2 is about one (!!!) day

I kept asking questions, trying to understand why you believed this. The first sentence was too vague to discuss, so I focused on the second.

We first agreed that by “lifetime” you meant “residence time”, rather than “adjustment time” (the timescale relevant for global warming).

Then, despite your initial claim that “any normal scientist understands it”, you changed your mind about the one day figure:

my “one day” estimation for residence time was a bit too low :-)

I don’t know if the smiley here means you agree it was much too low. The usually cited estimate is 3-4 years.

Your claim then shifted to something like this: human-produced carbon dioxide cannot build up in the atmosphere unless the large daily natural inflows and outflows of carbon dioxide precisely cancel each other. You seemed to claim that such a precise cancellation would be needed on short time scales and/or distance scale: otherwise it would be impossible for human-produced CO2 to gradually accumulate.

If this is indeed your claim, it is quite remarkable. So I want to know what mechanism you believe prevents the CO2 from accumulating.

One last point. You wrote:

If the natural fluxes do not practically cancel each other (as the expert Nathan told you so)…

This sentence is ambiguous. I can’t tell whether you’re saying Nathan said the fluxes do practically cancel each other, or do not practically cancel each other. Let’s be clear on what Nathan said:

Of course, there is practical cancellation of first order processes, which is why CO2 only fluctuates by a few ppm during the seasonal cycle, why CO2 was so stable during the Holocene interglacial, and only varied by ~100 ppm even between glacial-interglacial transitions.

I am perfectly willing to stop this discussion here, since we seem to agree now that your original claim (a) was false. If we stop here, I will not believe your claim that the accumulation of human-produced CO2 is unlikely. Maybe that’s okay with you.

We can then move on to examine your claim (b), or quit — whichever you prefer.

• Al Tekhasski says:

Jonh, you said: “since we seem to agree now that your original claim (a) was false.”

I already agreed that it was substantially off, and later corrected my estimation to about 300 days stretchable to 3 years. Yet you failed to admit that the claims of your presentation about “centuries” and “thousands of years” are misleading in context of this topic.

Now, regarding my skeptical statement (b), let me now begin with a question: why do you believe that CO2 doubling reduces global OLR by 3.7W/m2?

• John Baez says:

Al wrote:

I already agreed that it was substantially off, and later corrected my estimation to about 300 days stretchable to 3 years.

Oh, great! But let’s be precise, so I understand exactly what you are saying.

You are — I think — now saying that the average amount of time a CO2 molecule stays in the Earth’s atmosphere (the "residence time") is somewhere between 300 days and 3 years.

I am not sure what the “conventional” estimate of the residence time is.

Over on Skeptical Science I see the “turnover time” estimated at 3-4 years, and in a comment on that page you suggest a turnover time of 4-5 years.

Readers of this discussons will remember that the residence time is not the same as the turnover time. The United States Environmental Protection Agency gives this definition:

Residence Time: The average time spent in a reservoir by an individual atom or molecule. With respect to greenhouse gases, residence time usually refers to how long a particular molecule remains in the atmosphere.

The glossary of Climate Change 2007: Working Group I: The Physical Science Basis give this definition:

Turnover time (T) (also called global atmospheric lifetime) is the ratio of the mass M of a reservoir (e.g., a gaseous compound in the atmosphere) and the total rate of removal S from the reservoir: T = M / S.

If we carefully keep track of each time a CO2 molecule leaves the air, even if it re-enters the next day or next second, then the turnover time will, I believe, equal the residence time. But — as you pointed out — if our computation of the turnover time fails to count each time a CO2 molecule flows out of the air, we will get a turnover time that overestimates the residence time.

But, I am happy to let this issue rest, if you think I’ve accurately summarized your position.

Similarly, since you have repeatedly failed to answer this question:

Why do you think human-produced CO2 can accumulate in the atmosphere only if the ‘first order’ processes practically cancel each other?

I will assume you are unwilling to defend this claim.

Next, you say:

Yet you failed to admit that the claims of your presentation about “centuries” and “thousands of years” are misleading in context of this topic.

I have nothing to admit, since the statements in “week302” had nothing to do with turnover time or residence time! They concerned the “adjustment time”, which is defined by the IPCC as follows:

Adjustment time or response time (Ta) is the time scale characterising the decay of an instantaneous pulse input into the reservoir. The term adjustment time is also used to characterise the adjustment of the mass of a reservoir following a step change in the source strength. Half-life or decay constant is used to quantify a first-order exponential decay process.

It’s the adjustment time that matters for global warming, not the turnover time or residence time. You may have mistakenly believed that the adjustment time must equal the turnover time. It is easy to see that it’s possible for them to be different. And in fact, the adjustment time is much longer. This is what I was discussing in “week301”.

If you don’t have any further comments on this issue, we can move on to your point (b).

• Al Tekhasski says:

I do have a comment on (a). To start, my recent comment has nothing to do with your next “Week 302” presentation. So, please. Then, you put forth a comprehensive effort lecturing me about variety of “precise” definitions and trying to dig discrepancies in different estimations for different processes. Let’s re-examine my statement:

(a) Carbon “residence time” has nothing to do with anything. Any normal scientist understands that, given enormous diurnal magnitudes of local natural CO2 fluxes, the “lifetime” of CO2 is about one (!!!) day;

And compare it with your presentation that concluded with cumulative idea: “the carbon we burn will haunt our skies essentially forever… This is why we’re in serious trouble “.

First, my statement makes a distinction between “residence time” and “lifetime”, which apparently should be construed as “half-time”. Second, I already admitted (twice) that my hip shooting of “one day” was quite off, which I corrected later.

In contrast, your figure 7a describes an eclectic mix of terms. On the top it says “residence time”, but inside it says “New Equilibrium is Achieved after a few Centuries”, which is obviously referring to more like “adjustment time”, aka “response time”, or “half-life time”. I understand that you did not make that picture, but you used it to lead readers to a conclusion that “carbon is forever”.

As observations of “adjustment time” [ from eruption of Pinatubo] show, this time is about 3 years. This is the fact, in contrast to some web speculations from AGW catastrophists. Therefore, I maintain that claims of your presentation about “centuries” and “thousands of years” and “carbon forever” are misleading and wrong. I think you need to admit this before moving further.

• John Baez says:

John wrote:

I have nothing to admit, since the statements in “week302″ had nothing to do with turnover time or residence time!

Al wrote:

To start, my recent comment has nothing to do with your next “Week 302″ presentation. So, please.

Sorry, that was a typo. I meant “week301”.

In contrast, your figure 7a describes an eclectic mix of terms. On the top it says “residence time”, but inside it says “New Equilibrium is Achieved after a few Centuries”, which is obviously referring to more like “adjustment time”, aka “response time”, or “half-life time”. I understand that you did not make that picture, but you used it to lead readers to a conclusion that “carbon is forever”.

I’m glad you finally explained your remark “residence time has nothing to do with anything” — as soon as you made it, I said:

I didn’t actually mention “residence time” in week301, so I’m not sure why you bring it up only to dismiss it.

Now I understand: it’s in the caption of this figure prepared by Robert Rohde! I agree, he is using the term ‘residence time’ in a confusing way here.

Thanks for pointing this out. I have corrected the figure on “week301” and will email Rohde suggesting that he use the more appropriate term, “adjustment time”.

As observations of “adjustment time” [from eruption of Pinatubo] show, this time is about 3 years.

Okay, so your estimate of the adjustment time is vastly smaller than that of the United States Environmental Protection Agency and many peer-reviewed papers, for example these:

Carbon is forever, Nature Reports Climate Change, 20 November 2008. (Has a useful bibliography of recent literature.)

• TML Wigley, Balancing the carbon budget. Implications for projections of future carbon dioxide concentration changes, Tellus 45B (1993), 409-425.

The Global Carbon Cycle, SCOPE Vol 13, edited by B. Bolin, ET Degens, S Kempe and P. Ketner, John Wiley & Sons; 1979. (Old but useful.)

I have already brought these to your attention, so you shouldn’t claim that these longer estimates of the adjustment time are merely “web speculations from AGW catastrophists”. They are in fact quite widely accepted by climatologists.

So: if you wish to convince me that these longer estimates are wrong, please present your evidence. You mentioned Mt. Pinatubo. Could you point me to a source — preferably a refereed scientific paper — that uses Mt. Pinatubo observations to determine the adjustment time for carbon dioxide?

• Nathan Urban says:

John,

I think I’ve mentioned in our unpublished interview installment that “residence time” is sometimes applied to both types of time scale. Despite what the IPCC has said, I don’t know if the terminology has actually ever been standardized, even in the scientific literature. It invites misinterpretation.

You probably already know from what I said there that there are multiple response times in the carbon cycle. Fast volcanic events like Pinatubo mostly excite the high frequency response, and so can say very little about the longer response times. To estimate those from data, you obviously have to look at data over longer time scales.

• John Baez says:

Thanks, Nathan. And by the way: don’t feel the least obliged to get involved in this discussion I’m having with Al Tekhasski. I think it’s working pretty well with just the two of us. It probably looks incredibly slow and frustrating to you, but I’m just learning the basics, and a discussion with a determined opponent is actually a good way to do it. You must remember how many years I spent arguing physics with all and sundry on sci.physics. It’s no substitute for reading books and papers, but it’s a nice complement. I don’t have as much spare time these days, so I don’t really want a free-for-all where I match wits with everyone on the planet who has some ideas about climatology, but this discussion with Al is proving helpful.

31. westy31 says:

Did you hear about ocean fertilization?

A bit scary, but potentially very effective.

Gerard

• John Baez says:

Maybe the idea has potential, but the results of the tests so far don’t sound very promising:

• Kenneth Coale et al, A massive phytoplankton bloom induced by an ecosystem-scale iron fertilization experiment in the equatorial Pacific Ocean, Nature 383 (10 October 1996) 495 – 501.

On the BBC Kenneth Coale says:

“To date we’ve conducted experiments in what amounts to 0.04% of the ocean’s surface,” he told BBC News.

“All have indicated that iron is the key factor controlling phytoplankton growth, and most have indicated that there is carbon flux (towards the sea floor) – this is one that didn’t.”

Coale is talking about the experiment described at the Sietch Blog, which was led by Dr Wajih Naqvi and Dr Victor Smetacek. If you read his quote, you might think other experiments were getting significant amounts of carbon going to the sea floor. But Coale’s paper cited above says that while iron stimulated the growth of phytoplankton, “the magnitude of the biological and geochemical response was much smaller than predicted”.

Perhaps some fine-tuning is needed?

• westy31 says:

I was thinking,

The idea of fertilization to enhance the rate of plant growth of course applies equally to land as to sea.

Fertilisation greatly influences growth. I live an a very fertile area myself called ‘Betuwe’, but accross the river there is ‘Veluwe’, named after ‘good soil’ and ‘bad soil’ respectively. Maybe we should manage these minerals in a smarter way.

We know now that the easiest way to do it, nitrate based fertiliser, also has negative side effects. Nitrates get into the ground water, and methane into the air. I bet there are many ways to do it in a smarter way, avoiding these side effects.

Related to this is the fact that there is a 1.6 gTon/yr carbon flux into the atmosphere due to soil resuse. (Fossil fuel is 6.3 gTon/yr) Apparently, the way
we turn forest into agriculture is not smart.

How do you make fertile soil without contaminating the ground water and the atmosphere?

Gerard

• John Baez says:

Gerard wrote:

How do you make fertile soil without contaminating the ground water and the atmosphere?

People know a lot about how to do this. Some people do it — but most people don’t.

You’ll see a bit more about this in my interview with Thomas Fischbacher. That would be a good time for us to dig more deeply into these questions.

32. Ijon Tichy says:

I don’t think scientists (as scientists) can do any more than continue the vast amount of work they’re already doing in this area. It is up to the political leaders and the people they lead to push forward and implement solutions to this problem. As an admittedly pessimistic person, I don’t see the world’s major governments doing anything substantial to solve these problems. It’s only when things get really bad that emergency actions might be taken.

One of the most promising of these emergency responses that I have read about is large-scale extraction of CO2 from the atmosphere via the mineral olivine. This is a chemical process that already occurs in nature, but we can speed it up by mining it, grinding it down sufficiently, and spreading it over a wide area. The chemical reaction is:

Mg2SiO4 + 4 CO2 + 4 H2O –> 2 Mg2+ + 4 HCO3- + H4SiO4

(So 140 grams of olivine will sequester 176 grams of CO2, with the help of 72 grams of water, i.e. rain, seawater)

During major periods of tectonic uplift in the Earth’s past, huge slabs of olivine-rich rock (mostly peridotite) have been pushed up through the Earth’s crust, with some of it being exposed at the surface. The resulting chemical weathering caused or contributed to a significant drop in CO2 levels leading to global cooling.

Some work on this has been done by Olaf Schuiling, a professor in geochemistry at the University of Utrecht. The only online material on this subject I could find by him was a poster:

Let the Earth help us to save the Earth

• Graham says:

“A worldwide search is on for cheap processes to sequester CO2 by mineral reactions. Removal by reactions with olivine is an attractive option, because it is widely available and reacts easily with the (acid) CO2 from the atmosphere. When olivine is crushed, it weathers completely within a few years, depending on the grain size. All the CO2 that is produced by burning 1 liter of oil can be sequestered by less than 1 liter of olivine. The reaction is exothermic but slow. In order to recover the heat produced by the reaction to produce electricity, a large volume of olivine must be thermally well isolated. The end-products of the reaction are silicon dioxide, magnesium carbonate and small amounts of iron oxide.”

There’s some references too. I’m reading this one now.

http://www.netl.doe.gov/publications/proceedings/01/carbon_seq/6c1.pdf

33. John Baez says:

Ijon writes:

I don’t think scientists (as scientists) can do any more than continue the vast amount of work they’re already doing in this area.

I don’t exactly agree. Take me, for example. I’m a scientist. What was I doing to help save the planet? Nothing, essentially. Now I’m doing a bit more… and I hope to do even more in the years to come.

In short, I’m not asking for scientists already working on climate change, energy technology, etc. to redouble their efforts. I’m asking more scientists to get involved — starting with me. More scientists means more new ideas and also more sheer political mass. Though one sometimes gets the opposite impression, especially in the US, ordinary people actually do care what scientists think. And scientists involved in academia have a special role to play: education.

If things are heading the way I fear they’re heading, at some point lots of scientists will get involved — a bit too late. As Saul Griffith put it: don’t think of it as a Manhattan Project. Think of it as World War II, but with everyone fighting on the same side.

Thanks for pointing out that olivine reaction! The big question, as always, is how easily it could scaled up. At some point I’ll compare lots of geoengineering ideas on This Week’s Finds. This one was new to me.

Btw, Stanislaw Lem was one of my favorite SF authors when I was younger. Still is, I guess, but I ran out of stuff by him to read!

• Ijon Tichy says:

Another scientist like you who has turned his attention to this subject of climate change and potential solutions to it is Barry Brook from Australia. He has a blog with lots of articles you may find interesting:

Brave New Climate

• Crust says:

This paper by Hartmann and Kempe has a contrary take on the enhanced weathering idea. From the abstract:

Unless progress in application procedures is provided, the recent realistic maximum net-CO2-consumption potential is expected to be much smaller than 0.1% of anthropogenic emissions, and the SW [stimulated weathering] would thus not be one of the key techniques to reduce atmospheric CO2 concentration.

I don’t have any expertise on this, just found it from a Google search. The beauty of ideas to remove CO2 from the atmosphere compared to most other geoengineering ideas is it gets at the root cause of the problem; so it simultaneously deals with warming and ocean acidification.

As an aside, Al Gore and Richard Branson have offered a \$25 million prize if anyone can come up with a workable solution that removes a billion tons or more per year from the atmosphere. I hope they end up paying out!

34. Blug says:

John- congratulations on the new blog and for all the
interest it’s generating! It is a wonderful idea to get scientists thinking about these things not only because it is crucial to our survival, but because it can be interesting and even fun. That’s how to get people involved.

Apparently France (i.e. Sarkozy) has just announced a huge investment in fusion research. My guess is this is a huge mistake; fusion has been 20 years in the future for each of the last 50. And the S. regime has a pattern of choosing and then imposing ill-thought-out and very radical “reforms”, alienating many good people in the process.

35. Cui Piggy says:

We humans are a complex creature, both altruistic and self interested; compulsive gamblers yet risk averse; and focused on the small scale and immediate rather than the global and abstract. The psychology of how to change our collective destructive habits is a worthy challenge for study. Could, for example, the transtheoretical model of change (http://mdm.sagepub.com/content/28/6/845.abstract) guide strategy and policy rather than the blunt scare tactics and ‘megaphone’ approach (LISTEN TO US IT’S IMPORTANT) we scientists rely on?

The global climate challenge is almost too big for most people to grasp, and too abstract: most of us are far removed from the consequences of our consumption, or the production of those goods consumed. Many of us continue to gamble that this abstract potential harm will have no effect on our lives, while striving to avoid the small material losses (and get more of the material comforts) that do.

A price on carbon would bring the issue home, with an increased cost on energy and food. However, I’m unconvinced that small collective actions such as household or even corporate energy conservation will be sufficiently large to make a difference to global climate, though these will be a focus of much public interest when a tax on greenhouse gases is introduced.

So I don’t see a carbon tax leading to sufficient reduced energy consumption to have any impact on climate BUT, importantly, because we will go to great lengths to avoid paying costs like taxes, it might stimulate demand for investment into technology that may have an impact, and into the preservation and replanting of forests that might help reduce atmospheric carbon.

We change when we recognise that change meets our self interest. Could our simple desire to save a buck save the planet? And if not, what would motivate us to sufficient collective investment or action to make a difference?
Finally, I am astonished that we can consider ourselves capable of handling nuclear waste if we cannot manage something as ‘dangerous’ as carbon dioxide waste.

36. mtakuo says:

This is not about the main points, but for your possible amusement… The birth of pottery goes much longer before “-6000”. See here for example:
http://en.wikipedia.org/wiki/Jōmon_Pottery
According to another article there (written in Japanese), what may be fractures from the oldest pots were found 1998. Said to be around 16500 years old (but not firmly determined). I know that part of the world, but am culturally not those pots’ people’s descendant, unfortunately…
I am not a scientist but am training to be one. Your warnings on extinction of species were very shocking.

37. Mattias Wikström says:

You suggest that “the human race makes big decisions based on an economic model that ignores many negative externalities”. Without necessarily disagreeing, below is how I analyze the problem faced by the human race.

The problem is not money: If we did not have money we would just use gold or something else instead. The problem also is not the idea of ownership: Whether we call it ownership or not, as long as there are conflicts between people we need to know who has the right to use which resources in what ways. The problem is rather that whenever we have power (which may come in the form of “rights”) we need to use it in a responsible way, in accordance with ideals.

The great thing about using power in a responsible way is that you can forget about power. It does not really matter who is responsible for something as long as the responsibility is being handled properly. It does not matter whether you live in democratic country A or democratic country B as long as they both live up to the same democratic ideals. It does not matter whether you are buying a phone from company A or a phone from company B as long as they both make phones according to the same best practices on how phones should be made. And so on.

When people do not use power in a responsible way we get conflicts. Fortunately, competition between the different sides in a conflict can be a creative force that makes reason win. (Moreover, competition exists not only in unfriendly but also in friendly forms, and competition between nations, universities, political parties, charity organisations, companies, or divisions within a company can be a most fruitful thing, something that helps us be responsible.)

Competition involves positive and negative feedback, and I am afraid that a big organisation may be like an animal in that it understands little more than positive and negative feedback. Like an animal it takes care of itself and things it has been programmed to take care of, but the fact that it is made up from people rather than machines or cells prevents it from showing too much mobility. Instead, it is individuals who are responsible for applying positive and negative feedback at the right places so that organisations act in a responsible way.

In the case of global warming we should try to make sure that negative feedback is applied at anything that is responsible for CO2 pollution (perhaps in part by transferring the negative feedback nature is already giving many developing countries). Imagine a group of aliens trying to apply negative feedback at whatever is responsible for the planet destruction: They may start by trying to apply negative feedback at the United Nations, but they would then find they should instead turn to each of its members, and as they find nations to be very irresponsible they may instead try to apply negative feedback at politicians, voters, intellectuals, people who hold stocks in companies responsible for pollution, those who buy from or make deals with companies responsible for pollution, and so on. To do this they would need a lot of power, but in principle we have a lot of that power ourselves, and with power comes responsibility.

38. Renato Iturriaga says:

I think there is something that doesn’t fit or I don’t understand the amount of CO2 we are disseminating it looks more than the increments we observe, so I guess there is some absorption somewhere, but this contradicts your assertion that the carbon we burn will haunt our skies essentially forever.

My calculations
Area of the earth : 12 x (6.3×10^3)^2=480X10^6 km^2
Volume of Atmosphere: Area times 10= 4.8 x10^9 km^3
Weight of a 1m^3 of air 1 Kg
Weight of 1 km^3 of air 1X10^6 tons
Weight of the atmosphere 4.8 x10^15 tons

Then 30 X10^9 tons of CO2 in the atmosphere looks like 6.25 ppm.
In ten years of similar emissions we should see around 60 ppm increments, so if we see “only” 20 ppm in this ten years I guess there is some absorption somewhere.

• John Baez says:

The phrase ‘carbon is forever’ shouldn’t be taken too literally: it’s meant to remind you of a song. I didn’t check your calculations, but the ratio of 20 ppm to 60 ppm sounds roughly consistent with what I wrote above:

Once carbon dioxide is put into the atmosphere, about 50% of it will stay there for decades. About 30% of it will stay there for centuries. And about 20% will stay there for thousands of years:

• Renato Iturriaga says:

Thanks for your answer. I will read the papers, I hope I didn’t make a silly math mistake, but it will not be the first time. The graphs show that something around the 50 percent will disappear in 40 years and the calculation show that more than a half will disappear in less than ten years.

• John Baez says:

It wouldn’t be the first time I made a mistake, either.

But this is important, and fun, so let’s figure it out. At first I thought your calculation of the mass of the Earth’s atmosphere might be too oversimplified, but Wikipedia gives a figure of 5 × 1015 tonnes, which is quite close to your figure of 4.8 × 1015 tonnes, so that part seems okay.

Here’s another possible source of error: you seem to be using parts per million mass, but everyone involved in global warming talks about ‘ppmv’: parts per million volume. Actually you’ll see that the data from Mauna Loa are expressed in terms of parts per million moles. If I remember my ideal gas law correctly, that should be almost the same as ppmv. Indeed, you’ll see from that Mauna Loa data that in the last decade, CO2 has gone up 20 parts per million moles.

It’s pretty easy to convert from parts per million mass to parts per million moles if you know the molecular weight of CO2, N2 and O2, together with the fact that air is about 21% oxygen by volume, and the rest mainly nitrogen. I’m too busy to do the calculation right this second, but maybe you could adjust your calculation to take this into account?

• John Baez says:

A very rough guess is that for CO2 in air, parts per million moles is 2/3 of parts per million mass, since it has 3 atoms instead of the 2 we find in O2 and N2, and all these atoms are roughly the same mass.

39. Renato Iturriaga says:

By the level of accuracy of this discussion I am quite happy with the 2/3 argument. But just for fun, your suggestion should be
N_2 weights 28 and there is 79%
0_2 weights 32 and there is 21 %
CO_2 weights 44
We get
32/44 (.21)+ 28/44 (.79) = .152 + .502 =.655
As expected very near to .6666

So the 6.25 ppm of mass is now 4ppm of moles. Which still makes 40 in 10 years so half of it disappear before ten years, which is still 4 times faster of what the graph says.

• John Baez says:

Now it’s getting interesting! I hope Nathan Urban or someone else who actually works on climate science can comment on this apparent discrepancy. This calculation is so simple that surely someone has done it before.

If nobody helps clear up this question, and I seem to forget about it, could you please remind me in a couple of weeks? I’m going to Vietnam from Christmas until January 5th, just to have a look around in Hanoi and Huế. But afterwards, if nobody has solved this puzzle, I could do a blog entry on it, to increase the chance that some expert notices it.

• Renato Iturriaga says:

Happy Christmas, in the mean while i will try to read the papers. I have almost zero knowledge, but a lot of enthusiasm. Two years ago I read Mackay´s Without the hot air, and change a lot my habits, it is probably time for a next step, you are very inspiring, I am also a mathematician willing to think in this kind of problems.

• Graham says:

Renato and John:

I’m jumping in without reading what you’ve said properly, but I didn’t see anyone say that the oceans absorb about half of our CO2 emissions. A ref:

http://news.nationalgeographic.com/news/2004/07/0715_040715_oceancarbon.html

40. Renato Iturriaga says:

Dear Graham and John.

Thank you for your answers, I read the page that Graham suggested and the article of Archer, well the introduction and the conclusions the model part still needs more effort.

Probably the graph has to be corrected to show a quick absorption of the CO2 to the ocean. Say a little bit less than a half almost immediately. Also a good explanation of why the next half doesn’t gets absorbed also very quickly. As I said I still don’t understand the models but from what I read I imagine something like this.

The C02 in the atmosphere interacts in several cycles, the ocean, the biosphere, the soil, and the deep rocks at the bottom of the oceans. All this cycles have very different
time scales, In fact the ocean should be thought as several cycles, one is the surface layer, where the interaction is quick, and presumably has the same mixing rate as the atmosphere and then come deeper layers that have a bigger time scale
interaction. There are no sinks of C02, rather the C02 is in equilibrium in all this cycles, while this equilibrium is probably stable, meaning that nearby conditions will stay nearby it is probably not asymptotical stable, meaning that nearby conditions will not converge to the equilibrium or at least not in the time scale of the cycle. Like the pendulum where there is no friction, once that you move it will find another equilibrium –a periodic orbit with some energy- and you don’t expect to return to the rest position unless you turn on the friction. Once you put some extra C02 in the atmosphere some off it will be sucked by the surface layer of the ocean and the atmosphere and this first layer of the ocean will be in equilibrium, with some other concentration but it will not suck out the rest off it, we have to wait for the next time scale cycle to notice there was some increment to suck out much more slowly a considerable part of our emission, and so on.

Did I get it right?

• John Baez says:

I will need to read more before I can give you a good reply, and right now I’m I don’t have time (I’m on vacation), but I’m very glad you’re thinking about this. If that graph needs to be corrected, that’s a very important discovery!

41. Nigel Cook says:

Hi Dr Baez,

I’m a fan of your physics blog (This Week’s Finds) and I’m in Essex. Our coastline views are now cluttered with windfarms, which shut down in calm and very windy periods! (Wind causes breakdowns!)

While I agree with your assessment that there is a problem, why not solve it with nuclear power and spread the radioactive pollution around to prevent cancer from occurring in the first place: http://www.jpands.org/vol9no1/chen.pdf

W. L. Chen, Y. C. Luan, M. C. Shieh, S. T. Chen, H. T. Kung, K. L. Soong, Y. C. Yeh, T. S. Chou, S. H. Mong, J. T. Wu, C. P. Sun, W. P. Deng, M. F. Wu, and M. L. Shen, ‘Is Chronic Radiation an Effective Prophylaxis Against Cancer?’, published in the Journal of American Physicians and Surgeons, Vol. 9, No. 1, Spring 2004, pp. 6-10.

A dose rate of roughly 0.4 Sv per 9-20 years, i.e. a dose rate of 2.3-5.1 microGrays per hour (0.23-0.51 millirads per hour) or 23-51 times normal background causes the benefit of a fall in normal cancer rates by a factor of 116/3.5 = 33, and a fall in congenital heart malformations by a factor of 23/1.5 = 15. These are big numbers!

They were a representative group exposed to a known easily measured dose rate for many hours each night over many years. The surrounding population which didn’t live in the radioactive buildings forms a perfectly representative natural “control group”, better than those in Hiroshima and Nagasaki which were populations outside the close-in target areas. Those Japanese control groups had less worries about long-term radiation scare stories than nuclear survivors, so they had lower stress levels and related lower smoking rates on average, and were not so likely to get cancer or heart disease for those reasons even before radiation effects are considered!

What is happening here is the “what doesn’t kill you makes you stronger” effect: dose rates of 20-50 times normal background over a period of 1-2 decades stimulates a stronger DNA repair enzyme system. The body simply devotes more energy from food into building more DNA repair enzymes, and it over-compensates, thereby reducing natural cancer rates.

• Graham says:

See

for more (and more recent) studies and debate.

• John Baez says:

I favor rapidly developing nuclear power as part of a solution to our energy problems. Here’s one plan, and some criticism of that plan:

Nuclear Century Outlook, Azimuth Project.

The main problems are political: the real danger of weapons proliferation, and the largely exaggerated fear of nuclear waste. The idea of curing cancer by throwing nuclear waste around is intriguing and amusing, but regardless of whether the science is right, it’s a divisive side-issue. So I don’t plan to spend any time thinking about this.

By the way does someone have an explanation for the steam which as it seems is being pushed out at reactor 3?

TEPCO writes

※ 48 At around 7:00 am on December 27, and confirmed by the camera that from Unit 3 reactor building, 5th floor near the center, steam is generated. Have not been identified abnormal plant conditions of 54 minutes at 7:00 am the same day, the indicated value of the monitoring post (meteorological data of 50 minutes at 7:00 am, 5.1 ℃ temperature, 93.1% humidity).

• Hank Roberts says:

See if you can find the origin of that; when I look for it, I find a handful of blogs quoting the same thing, but nothing recent from Tepco as a primary source since sometime last July. It may be old news, not new news.

@Hank Roberts

The link “TEPCO writes” above links to TEPCO (i.e. the electricity company, which is in charge for the Fukushima power plant). I cited a Google-translated remark from that japanese page reporting about an incident on Dec 27, 2013 (the year is in the header) – if Google translate is correct. It’s a bit hard to find this report among all the other reports.

You can find criticism also in an overview given
at our blog at:http://www.randform.org/blog/?p=3249

(It is also linked to from the Azimuth page http://www.azimuthproject.org/azimuth/show/Nuclear+power)

The reaction of human bodies to radioactivity is rather complex. In particular you have of course crucially different forms of radioacivity.

In particular you should observe that Cobalt-60 which is the subject of the study “Is Chronic Radiation an Effective Prophylaxis Against Cancer?” emits no alpha particles during decay, whereas e.g. Plutonium 239 does.

In the overview a link is given to a study about increased cancer rates in the vicinity of german nuclear power plants.
http://www.randform.org/blog/?p=1629

43. Love your blog! Thanks alot!

I’ve seen somewhere that the total flux of the Earth’s magnetic field varies, and same true of the total flux of solar luminosity. If this is true, please compare combinations of changes to these fields (the lowering of the magnetic flux of the Earth in combination with the rising of the solar flux), in “units of atmospheric warming”, with the warming due to one CO2 molecule increase per ten thousand atmospheric molecules (100ppm)?

Finally, on nuclear power, I write this: the Myth of Prometheus is that he stole fire from the gods to master his own destiny; the knowledge of fire that had once been so uncontrollably lethal to early man becomes his liberation from the whims of nature.

I completely support the research and development of nuclear fission energy and power. I am confident humanity will one day be it’s master; that this knowledge will be the vanguard of nuclear fusion, and other natural forces yet unimagined.

However, if over the last 40 years, the catastrophic failure rates of nuclear plants have been normal, and not extreme (regardless of the details of their causes). If there are built another 800 nuclear plants over the next 40 years (while retiring these existing 400), we can expect another failure unless they are built more than than four times safer. Likewise, a catastrophic failure rate of one per sixteen hundred nuclear plants over eighty years requires building plants eight times safer.

Plants need to be built safer by an order of magnitude not marginally.

• Nathan Urban says:

There are many places to find climate radiative forcings, for example NASA GISS. The bottom figure has time series. Solar forcing is the orange wiggly curve partially obscured by the red curve. It’s of order 0.1 W/m^2. Greenhouse gases are the green curve, of order 2.5 W/m^2. The 100 ppm increase in CO2 accounts for about half of that, with other greenhouse gases (methane, CFCs, nitrous oxide, and ozone) making up the other half.

I don’t know how to compare the flux of the Earth’s magnetic field in “units of warming” (radiative forcing), because I don’t know of a mechanism for a lowering planetary magnetic flux to cause warming.

44. John Baez says:

Charles wrote:

I’ve seen somewhere that the total flux of the Earth’s magnetic field varies, and same true of the total flux of solar luminosity. If this is true, please compare combinations of changes to these fields (the lowering of the magnetic flux of the Earth in combination with the rising of the solar flux), in “units of atmospheric warming”, with the warming due to one CO2 molecule increase per ten thousand atmospheric molecules (100ppm)?

Instead of “units of atmospheric warming” I’ll discuss radiative forcing, which is easier. Radiative forcing is measured in watts per square meter. It’s a measure of the power per square meter due to a given warming effect. For a more precise definition, click on the link!

I only have the energy to compare the radiative forcings due to solar luminosity and CO2.

I’ve never heard of radiative forcings due to changes in the Earth’s magnetic field. I suppose they must exist, but the effect sounds tiny—at least discounting times when the Earth’s magnetic north and south poles trade places. Those might be a bit more exciting, but the last time that happened was the Brunhes–Matuyama reversal, 780,000 years ago. That’s several ice ages ago!

(For more details on the pictures, just click them!)

Anyway: you’ll see below that the solar constant has varied by about 1/2 watt per square meter since 1880. The ‘solar constant’, which is not really constant, is the watts per square meter of solar radiation hitting the top of the Earth’s atmosphere when the sun is directly overhead:

But the Earth is a sphere. S the Sun is not directly overhead everywhere—and half the time it’s night! So, we must divide the solar constant by 4 to get the world-wide average of solar power per square meter hitting the top of the Earth’s atmosphere. That brings the relevant number down to 1/8 watts per square meter. We should also multiply by about 0.7 to take into account the fact that some sunlight bounces off the clouds.

So, it seems variations in the Sun’s brightness have caused variations of roughly 0.1 watts per square meter in solar forcing, in the period since 1880.

On the other hand, doubling CO2 is believed to cause a radiative forcing of about 4±0.3 watts per square meter. Note that each time you double CO2, you get roughly the same amount of extra radiative forcing!

So, it doesn’t make too much sense to ask about radiative forcing “per 100 ppm of CO2“: that depends a lot on where you start counting.

But suppose we start where we are today: now the atmosphere has 390 ppm of CO2. If we boosted that by 100 ppm, we’d have 490. Now

$\log_2(490/390) = 0.329...$

which means that boosting the CO2 concentration by 100 ppm from its present value would cause about “one third of a doubling” of the concentration. So, the radiative forcing would be about one third of 4±0.3 watts per square meter. Or in other words, somewhere between 1.2 and 1.4 watts per square meter.

I hope someone checks my calculation for arithmetic mistakes and other mistakes! I’m doing this for the first time here…

While we’re at it, I should also say that since the beginning of the industrial revolution, greenhouse gases have caused about 2.25 watts per square meter of radiative forcing.

In short, if I haven’t screwed up:

• In the period since 1880, variations in the Sun’s brightness have caused variations of roughly 0.1 watts per square meter in radiative forcing.

• Since the beginning of the industrial revolution, greenhouse gases have caused about 2.25 watts per square meter of radiative forcing.

• Boosting the CO2 concentration by 100 ppm from its present value would cause somewhere between 1.2 and 1.4 watts per square meter of additional radiative forcing.

45. Again, thank you so much for your reply, it’s an honor.

Below are two sources. One, from the British Geological Survey, showing an 8% reduction in the Earth’s magnetic dipole moment over the last 100 years; the BGS sites this data in a context of pole reversals.

The second source is from the National Oceanic and Atmospheric Administration; this data is often sited by such claims as.. “Solar Geomagnetic Ap Index Now at Lowest Point in its Record” etc.

In addition, perhaps even more importantly, other sources observe magnetic pole shifts from approximately 70N to about 80N in the last one hundred years.

How these three changes in the magnetic field strength and orientation, which are relatively large changes on a percentile basis, compare to the 1/2 unit of Total Solar Irradiance, or to the 2.25 watts of forcing due to “due to one CO2 molecule increase per ten thousand atmospheric molecules (100ppm)”, is still very mysterious to me, and so I remain skeptical.

My initial impression, based on percentiles alone, but without serious physical research or experimentation, is the “magnetic field forcings” appear significant.

“Earth’s Magnetic Dipole vs. Time”

“Interplanetary Magnetic Field”

46. Kenneth Florek says:

It is my understanding that all the hydrocarbons in geological strata comes through one source, living things, and these living things got it through some chain of other living things, ultimately from gases in the atmosphere or dissolved in water. Since the Cambrian (when fossil shells first show up), and probably immensely before, this gas has been carbon dioxide. Then, at some time, all this carbon was in the atmosphere, and the amount of carbon dioxide must have been tremendously larger than it is today. Is this incorrect, or just an odd-seeming fact?

If OTOH carbon has been added to the atmosphere, regardless of the source, and not just re-circulated in a carbon cycle, is it being added today by the same means?

Another observation relating to atmospheric carbon dioxide is as follows. Photosynthesis produced all the oxygen in the atmosphere, which is 21%, by producing oxygen and sugar from water and carbon dioxide. For every one CO2 input there is one O2 output. Then at some time instead of 21% O2, the amount of carbon dioxide in the atmosphere was 21%, versus the current 0.039%.

These life-derived carbon compounds, besides all the coal and oil, all the tars sands, all the oil shale, all the peat bogs and muskeg, and all the soil humus, include all the carbonates in sedimentary rocks. From the looks of geological formations, it would appear the quantity of carbonates must dominate the amount of fossil hydrocarbons by an immense factor. Carbonate, in some amount, is produced when carbon dioxide is dissolved in water, but then so will it if any carbonate compound is dissolved. Is it a fact that this carbon in carbonates is also ultimately, through some chain, comes from carbon dioxide? Or has the carbon been dissolved out of solids as the ultimate, non-recirculating source, and might it still be?

Rather than sequestering carbon underground, would not sequestering from the oceans (since purportedly half of it is being conveniently dissolved there already) be a more pragmatic solution? Some micro-organism that tends to precipitate carbonate already, and there are no doubt a lot, could be used as-is, selected-for, or genetically modified. Maybe micro-evolution is generating them for us at the current moment, and the missing one half of carbon emissions is not being dissolved in the ocean after all, but is being precipitated and falling to the sea floor.

• John Baez says:

No thread is ever dead, here! We’re talking about some big important topics, and these conversations deserve to go on for quite a while…

Since the Cambrian (when fossil shells first show up), and probably immensely before, this gas has been carbon dioxide. Then, at some time, all this carbon was in the atmosphere, and the amount of carbon dioxide must have been tremendously larger than it is today. Is this incorrect, or just an odd-seeming fact?

The carbon cycle has changed a lot over the course of the Earth’s history. I know just a little about this. The Earth’s ‘first atmosphere’ was mainly hydrogen, but this was soon lost to space. The ‘second atmosphere’, dating to around 3.4 billion years ago, was mainly carbon dioxide and water vapor, with some nitrogen, but probably not much oxygen. This second atmosphere had about 100 times as much gas as today’s ‘third atmosphere’. So yes, at this point there was a lot of carbon dioxide in the air.

(By coincidence, the Sun was also considerably dimmer then. Also, I’m speaking of a time before photosynthesis started.)

Rather than sequestering carbon underground, would not sequestering from the oceans (since purportedly half of it is being conveniently dissolved there already) be a more pragmatic solution?

As you note, nature is already busy doing this form of carbon sequestration: most of the carbon dioxide we emit is going into the ocean! The price we’re starting to pay is ocean acidification. Deliberate carbon sequestration in the ocean would increase this problem, but since we have no easy perfect solution to global warming, it might be interesting to see whether it’s possible to deliberately dissolve more CO2 in the ocean over long periods of time, or whether it equilibriates with the atmosphereric CO2 too fast.

• Hank Roberts says:

it’s possible to deliberately dissolve more CO2—but not a good idea.

http://www.earth.columbia.edu/articles/view/2951
—-excerpt follows—-
The world’s oceans may be turning acidic faster today from human carbon emissions than they did during four major extinctions in the last 300 million years, when natural pulses of carbon sent global temperatures soaring, says a new study in Science. But if CO2 goes into the oceans too quickly, it can deplete the carbonate ions that corals, mollusks and some plankton need for reef and shell-building.

That is what is happening now. In a review of hundreds of paleoceanographic studies, a team of researchers from five countries found evidence for only one period in the last 300 million years when the oceans changed even remotely as fast as today: the Paleocene-Eocene Thermal Maximum, or PETM, some 56 million years ago.

47. […] in serious trouble — for a short rundown, read this. It sounds pompous, but “saving the planet” is a convenient shorthand for tackling the complex […]