Melting Permafrost (Part 2)

This summer a Russian research ship found hundreds of plumes of methane, “of a fantastic scale”, bubbling up from the sea floor off the East Siberian coast:

• Steve Connor, Shock as retreat of Arctic sea ice releases deadly greenhouse gas, 13 December 2011.

Here are the quotes with actual new information:

In late summer, the Russian research vessel Academician Lavrentiev conducted an extensive survey of about 10,000 square miles of sea off the East Siberian coast. Scientists deployed four highly sensitive instruments, both seismic and acoustic, to monitor the “fountains” or plumes of methane bubbles rising to the sea surface from beneath the seabed.

“In a very small area, less than 10,000 square miles, we have counted more than 100 fountains, or torch-like structures, bubbling through the water column and injected directly into the atmosphere from the seabed,” Dr Semiletov said. “We carried out checks at about 115 stationary points and discovered methane fields of a fantastic scale – I think on a scale not seen before. Some plumes were a kilometre or more wide and the emissions went directly into the atmosphere – the concentration was a hundred times higher than normal.”

and

“This is the first time that we’ve found continuous, powerful and impressive seeping structures, more than 1,000 metres in diameter. It’s amazing,” Dr Semiletov said. “I was most impressed by the sheer scale and high density of the plumes. Over a relatively small area we found more than 100, but over a wider area there should be thousands of them.”

Scientists estimate that there are hundreds of millions of tonnes of methane gas locked away beneath the Arctic permafrost, which extends from the mainland into the seabed of the relatively shallow sea of the East Siberian Arctic Shelf. One of the greatest fears is that with the disappearance of the Arctic sea-ice in summer, and rapidly rising temperatures across the entire region, which are already melting the Siberian permafrost, the trapped methane could be suddenly released into the atmosphere leading to rapid and severe climate change.

Dr Semiletov’s team published a study in 2010 estimating that the methane emissions from this region were about eight million tonnes a year, but the latest expedition suggests this is a significant underestimate of the phenomenon.

I’d like to know more about Igor Semiletov’s work and what he’s just found. He was mentioned in this earlier very good article:

• Amanda Leigh Mascarelli, A sleeping giant?, Nature Reports Climate Change, 5 March 2009.

Namely:

The Siberian Shelf alone harbours an estimated 1,400 billion tonnes of methane in gas hydrates, about twice as much carbon as is contained in all the trees, grasses and flowers on the planet. If just one per cent of this escaped into the atmosphere within a few decades, it would be enough to cause abrupt climate change, says Shakhova. “When hydrates are destabilized, gas is released under very high pressure,” she says. “So emissions could be massive and non-gradual.” Shakhova and her colleague Igor Semiletov of the University of Alaska, Fairbanks, believe the plumes they’ve observed confirm previous reports that the permafrost cap is beginning to destabilize, allowing methane to escape from the frozen hydrates below. “Subsea permafrost is like a rock,” explains Semiletov. “It works like a lid to prevent escape of any gas. We believe that the subsea permafrost is failing to seal the ancient carbon pool.”

But Carolyn Ruppel, a geophysicist with the US Geological Survey in Woods Hole, Massachusetts, isn’t yet ready to attribute the methane plumes to a breakdown in methane hydrates in the subsea permafrost. “We have proof from studies that have been carried out in the past few years that there’s a lot of methane in certain shallow marine environments offshore in the Arctic,” says Ruppel. “But can we prove that the methane comes from methane hydrates? That is a critical question.”

Why is it critical? Because people are worried about global warming melting permafrost and gas hydrates on the ocean floor. Suppose these release large amounts of methane, a greenhouse gas vastly more potent than carbon dioxide. This will then makes the Earth even warmer, and so on: we have a feedback loop. In a real nightmare scenario, we could imagine that this feedback actually leads to a ‘tipping point’, where the climate flips over to a much warmer state. And in the worst nightmare of all, we can imagine something like Paleocene-Eocene Thermal Maximum, a spike of heat that lasted about 20,000 years, causing significant extinctions.

Are any of these nightmares really possible? I wrote about this question before, assembling what facts I could easily find:

Melting permafrost (Part 1).

How much new light does Semiletov’s work shed on this question?

Luckily, a team of scientists is gearing up to answer it:

Permafrost Carbon Network (RCN).

Here’s a paper by this team:

• Edward A. G. Schuur, Benjamin Abbott and the Permafrost Carbon Network, High risk of permafrost thaw, Nature 480 (1 December 2011), 32-33.

To get the ball rolling, they surveyed themselves. That may seem like a lazy way to write a paper, but I don’t mind it as a quick way to get a sense of the conventional wisdom… and they probably wanted to do it just to find out what they all thought! Here are the results—emphasis mine:

Our survey asks what percentage of the surface permafrost is likely to thaw, how much carbon will be released, and how much of that carbon will be CH4, for three time periods and under four warming scenarios that will be part of the Intergovernmental Panel on Climate Change Fifth Assessment Report. The lowest warming scenario projects 1.5 °C Arctic warming over the 1985–2004 average by the year 2040, ramping up to 2 °C by 2100; the highest warming scenario considers 2.5 °C by 2040, and 7.5 °C by 2100. In all cases, we posited that the temperature would remain steady from 2100 to 2300 so that we could assess opinions about the time lag in the response of permafrost carbon to temperature change.

The survey was filled out this year by 41 international scientists, listed as authors here, who publish on various aspects of permafrost. The results are striking. Collectively, we hypothesize that the high warming scenario will degrade 9–15% of the top 3 metres of permafrost by 2040, increasing to 47–61% by 2100 and 67–79% by 2300 (these ranges are the 95% confidence intervals around the group’s mean estimate). The estimated carbon release from this degradation is 30 billion to 63 billion tonnes of carbon by 2040, reaching 232 billion to 380 billion tonnes by 2100 and 549 billion to 865 billion tonnes by 2300. These values, expressed in CO2 equivalents, combine the effect of carbon released as both CO2 and as CH4.

Our estimate for the amount of carbon released by 2100 is 1.7–5.2 times larger than those reported in several recent modelling studies, all of which used a similar warming scenario. This reflects, in part, our perceived importance of the abrupt thaw processes, as well as our heightened awareness of deep carbon pools. Active research is aimed at incorporating these main issues, along with others, into models.

Are our projected rapid changes to the permafrost soil carbon pool plausible? The survey predicts a 7–11% drop in the size of the permafrost carbon pool by 2100 under the high-warming scenario. That scale of carbon loss has happened before: a 7–14% decrease has been measured in soil carbon inventories across thousands of sites in the temperate-zone United Kingdom as a result of climate change. Also, data scaled up from a single permafrost field site point to a potential 5% loss over a century as a result of widespread permafrost thaw. These field results generally agree with the collective carbon-loss projection made by this survey, so it should indeed be plausible.

Across all the warming scenarios, we project that most of the released carbon will be in the form of CO2 with only about 2.7% in the form of CH4. However, because CH4 has a higher global-warming potential, almost half the effect of future permafrost-zone carbon emissions on climate forcing is likely to be from CH4. That is roughly consistent with the tens of billions of tonnes of CH4 thought to have come from oxygen-limited environments in northern ecosystems after the end of the last glacial period.

All this points towards significant carbon releases from permafrost-zone soils over policy-relevant timescales. It also highlights important lags whereby permafrost degradation and carbon emissions are expected to continue for decades or centuries after global temperatures stabilize at new, higher levels. Of course, temperatures might not reach such high levels. Our group’s estimate for carbon release under the lowest warming scenario, although still quite sizeable, is about one-third of that predicted under the strongest warming scenario.

I found this sentence is a bit confusing:

These values, expressed in CO2 equivalents, combine the effect of carbon released as both CO2 and as CH4.

But I guess that combined with a guess like “30 billion to 63 billion tonnes of carbon by 2040”, it means that they’re expecting a release of carbon dioxide and methane that’s equal, in its global warming potential, to what you’d get from burning 30 to 63 billion tonnes of carbon, turning it all into carbon dioxide, and releasing it into the atmosphere.

For comparison, in 2010 humanity burnt 8.3 billion tonnes of carbon. So, at least up to 2040, I guess they’re expecting the effect of melting permafrost to be roughly 1/8 to 1/4 of the direct effect of burning carbon.

12 Responses to Melting Permafrost (Part 2)

  1. Arrow says:

    But how is the discovery of methane plumes relevant for GW?

    Do they claim that the tiny increase in global temperature somehow triggered this release of methane from seabed?

    The plumes were likely there for centuries and the methane they release gets to atmosphere ice sheet or not.

    It can even be seen as reassuring in the sense that discovering huge previously unaccounted for (or at least not fully) natural sources of greenhouse gasses makes our own contributions carry less relative weight.

    • gowers says:

      Let me give a tentative reply to two of your points.

      Do they claim that the tiny increase in global temperature somehow triggered this release of methane from seabed?

      A tiny increase in temperature from just below the freezing point of water to just above it makes the difference between ice melting and ice not melting. So near the boundary of a region where ice traps methane, one would expect a small temperature increase to make a significant difference.

      The plumes were likely there for centuries

      Can you justify this? It sounds like pure supposition to me, though it’s obviously important to understand whether the amount of methane being released is changing.

      It can even be seen as reassuring in the sense that discovering huge previously unaccounted for (or at least not fully) natural sources of greenhouse gasses makes our own contributions carry less relative weight.

      The absolute weight is pretty important. Indeed, if there’s already a large and destructive natural warming effect, one could argue that we will be much more vulnerable — so our own contributions become more destructive. To put that another way, if we increase temperatures by a degree from what they are now, that’s probably not nearly as bad as increasing them from 2 degrees above what they are now to 3 degrees above what they are now.

    • John Baez says:

      The not-so-tiny increases in Arctic ocean temperatures have caused a quite stunning decrease in Arctic sea ice volume, as shown in this graph using data from the Pan-Arctic Ice Ocean Modeling and Assimilation System:

      This decrease in volume is much more rapid than the decrease in area; the reason must be that ice is melting beneath the surface. I’ve heard it said this is caused by new warm currents coming into the Arctic Ocean. So, it’s at least conceivable that permafrost is also starting to melt at the ocean floor. But I think people need to study this: obviously you can’t jump from data about melting ice near the surface to melting ice near the sea floor.

      It can even be seen as reassuring in the sense that discovering huge previously unaccounted for (or at least not fully) natural sources of greenhouse gasses makes our own contributions carry less relative weight.

      Sorry, it’s not very hard to measure how much methane is in the Arctic atmosphere; we knew there were mysterious sources of the stuff. We also know how much of the current global warming is due to human sources of CO2. There will be moderate corrections to this picture as we continue to learn more, but nothing ‘huge’ or ‘reassuring’.

      There’s a nice new paper on this subject, just one of many:

      Huber and Knutti Quantify Man-Made Global Warming, Skeptical Science, 10 December 2011.

      And clearly, if higher temperatures trigger more methane releases from permafrost on land and the sea floor, this will make matters worse, not better.

    • Arrow has nailed it. It is not improbable that the time will come when global warming is as natural as it is anthropogenic today. It would by then be quite undeniable.

      I have some hope that by then hominin technologists will no longer feel offended upon suggestions of implementing some stone age technology (char coal production and agricultural sequestration) to balance the carbon budget. (With luck they could happily play with improved Imbert gasifiers plugged to a micro gas turbine or placed in a plain old Toyota Prius… and exchange the char for food.) I have less hope they will devise a monetary system to foster such economic activity…

  2. Hudson Luce says:

    All of this is fine and good, but trying to use this information to try to create politically-driven change is going to go absolutely nowhere. You’re asking governments to make a significant redirection of the global economy, with concomitant and extreme dislocations in the lives of hundreds of millions of people, in order to forestall or prevent a 4 degree Fahrenheit rise in average temperature by 30 years from now.

    First of all, who cares about the average annual temp going up by 4degF? What would be the impacts on agriculture, food supply, UV radiation, desertification, albedo… and so on? You have to show a pretty big effect by, say, 2060 or so, when most of the people now living, children and grandchildren already in existence, would be at the middle or end of their lifespans, to justify the radical change in lifestyle needed to avoid the catastrophe.

    • John Baez says:

      Hudson wrote:

      All of this is fine and good, but trying to use this information to try to create politically-driven change is going to go absolutely nowhere.

      You’re right. But as I’ve said before, this blog is not about trying to stir masses of people into political action. It’s about trying to get scientists and engineers interested in figuring out what’s going on, and figuring out things we can do.

      I don’t expect most people to get excited about methane bubbling up from the Arctic ocean: at least, not for long enough to do anything. But we need to understand the role of permafrost and gas hydrates in global warming. This discovery by Semiletov is important. And it’s exactly the sort of thing that can make some kids want to become scientists and take a trip on that boat off the East Siberian coast, to figure out what’s going on. My blogging used to attract lots of students to quantum gravity and n-categories. Now it’s environmental issues, complex systems, and the like.

      By the way, the mathematician Kenneth Golden has the greatest way to attract students that I’ve ever seen: he shows them what it’s like to ride through a storm on a ship headed for Antarctica! He works on the mathematics and physics of sea ice. There’s nothing like this to dispel the myth that math is for wimps:

      Hudson wrote:

      You’re asking governments to make a significant redirection of the global economy, with concomitant and extreme dislocations in the lives of hundreds of millions of people, in order to forestall or prevent a 4 degree Fahrenheit rise in average temperature by 30 years from now.

      I don’t recall asking governments anything.

      First of all, who cares about the average annual temp going up by 4degF?

      Are you asking for a list? Here’s one:

      • Wynne Perry, 2 degrees of warming a recipe for disaster, NASA scientist says, Live Science, 6 December 2011.

      Just kidding—I know your question was rhetorical.

      Anyway, I don’t think masses of people will take radical action unless and until things are getting worse at a noticeable rate and they feel these actions are likely to make things better.

      It’s possible that this will never happen, even if things get really bad. If things get bad slowly enough and it always seems hard to do anything useful, there may never come a moment where people rally and take action.

      Or, it’s possible that things will get bad and then people will desperately grab for something that seems like a quick fix, say geoengineering.

      Or, it’s possible that things don’t get really bad: we just muddle through.

      Or, it’s possible that more and more people will see that we have a growing problem that we can address by taking significant action. Scientists and engineers can help prepare a menu of options: what’s possible, what’s not.

      It sounds like you’re criticizing me because you feel you’re doing something more immediately practical. I wouldn’t be surprised if you were—practicality was never my strong point! What are you doing?

      • markwayne says:

        Or a new type of behavior in the global climatological system characterized by rapid (decades-scale) change, similar to the familiar phase transitions observed in many nonlinear dynamical systems precludes ‘people’ from doing anything at all. Happy Holidays!

  3. Hybrid Moiety says:

    Giant plumes of methane gas being released in the arctic sea is just very bad news. These very potent feedback effects kicking in earlier than we thought means we will have less time to respond.

    I still think Molten Salt Reactor technology is our best hope of a long term solution. A one billion US dollar development program coordinated by the Czech Republic nuclear researchers will have some good synergy in the Western Europe, and should bring Molten Salt Reactors to the deployment stage.

  4. John Baez says:

    Over on Google+, Stewart Brand pointed out this article “putting the new methane findings is somewhat less alarming context”:

    • Andrew Revkin, The heat over bubbling Arctic methane, Dot Earth, 3 March 2010 (updated 11 December 2011).

    Ed Dlugokencky, quoted here, works for NOAA and has been studying the rise in atmospheric methane concentrations for some time. He doesn’t think we’re close to a tipping point, but he does believe the worldwide rise in atmospheric concentrations is linked to the warming of northern regions:

    In a BBC article from 2008 he’s quoted as follows:

    Ed Dlugokencky, the scientist at Noaa’s Earth System Research Laboratory (ESRL) who collates and analyses data from atmospheric monitoring stations, agrees that the 2007 rise has a biological cause.

    “We’re pretty sure it’s not biomass burning; and I think 2007 is probably down to wetland emissions,” he said.

    “In boreal regions it was warmer and wetter than usual, and microbes there produce methane faster at higher temperatures.”

    Dr Dlugokencky also suggested that the drastic reduction in summer sea ice around the Arctic between 2006 and 2007 could have increased release of methane from seawater into the atmosphere.

  5. A fairly quick way to suppress tundra warming is through SO2 aerosols lofted by planes in the Arctic summer. Cost I estimated 6 years ago at $200 million to $300 million yearly.

    The Inuit would certainly like to see something like this done. Their roads thaw in summer, making transport harder. Animal patterns shift, too.

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