New IPCC Report (Part 8)

guest post by Steve Easterbrook

(8) To stay below 2°C of warming, most fossil fuels must stay buried in the ground

Perhaps the most profound advance since the previous IPCC report is a characterization of our global carbon budget. This is based on a finding that has emerged strongly from a number of studies in the last few years: the expected temperature change has a simple linear relationship with cumulative CO2 emissions since the beginning of the industrial era:

(Figure SPM.10) Global mean surface temperature increase as a function of cumulative total global CO2 emissions from various lines of evidence. Multi-model results from a hierarchy of climate-carbon cycle models for each RCP until 2100 are shown with coloured lines and decadal means (dots). Some decadal means are indicated for clarity (e.g., 2050 indicating the decade 2041−2050). Model results over the historical period (1860–2010) are indicated in black. The coloured plume illustrates the multi-model spread over the four RCP scenarios and fades with the decreasing number of available models in RCP8.5. The multi-model mean and range simulated by CMIP5 models, forced by a CO2 increase of 1% per year (1% per year CO2 simulations), is given by the thin black line and grey area. For a specific amount of cumulative CO2 emissions, the 1% per year CO2 simulations exhibit lower warming than those driven by RCPs, which include additional non-CO2 drivers. All values are given relative to the 1861−1880 base period. Decadal averages are connected by straight lines.

(Figure SPM.10) Global mean surface temperature increase as a function of cumulative total global CO2 emissions from various lines of evidence. Multi-model results from a hierarchy of climate-carbon cycle models for each RCP until 2100 are shown with coloured lines and decadal means (dots). Some decadal means are indicated for clarity (e.g., 2050 indicating the decade 2041−2050). Model results over the historical period (1860–2010) are indicated in black. The coloured plume illustrates the multi-model spread over the four RCP scenarios and fades with the decreasing number of available models in RCP8.5. The multi-model mean and range simulated by CMIP5 models, forced by a CO2 increase of 1% per year (1% per year CO2 simulations), is given by the thin black line and grey area. For a specific amount of cumulative CO2 emissions, the 1% per year CO2 simulations exhibit lower warming than those driven by RCPs, which include additional non-CO2 drivers. All values are given relative to the 1861−1880 base period. Decadal averages are connected by straight lines.

(Click to enlarge.)

The chart is a little hard to follow, but the main idea should be clear: whichever experiment we carry out, the results tend to lie on a straight line on this graph. You do get a slightly different slope in one experiment, the “1% percent CO2 increase per year” experiment, where only CO2 rises, and much more slowly than it has over the last few decades. All the more realistic scenarios lie in the orange band, and all have about the same slope.

This linear relationship is a useful insight, because it means that for any target ceiling for temperature rise (e.g. the UN’s commitment to not allow warming to rise more than 2°C above pre-industrial levels), we can easily determine a cumulative emissions budget that corresponds to that temperature. So that brings us to the most important paragraph in the entire report, which occurs towards the end of the summary for policymakers:

Limiting the warming caused by anthropogenic CO2 emissions alone with a probability of >33%, >50%, and >66% to less than 2°C since the period 1861–1880, will require cumulative CO2 emissions from all anthropogenic sources to stay between 0 and about 1560 GtC, 0 and about 1210 GtC, and 0 and about 1000 GtC since that period respectively. These upper amounts are reduced to about 880 GtC, 840 GtC, and 800 GtC respectively, when accounting for non-CO2 forcings as in RCP2.6. An amount of 531 [446 to 616] GtC, was already emitted by 2011.

Unfortunately, this paragraph is a little hard to follow, perhaps because there was a major battle over the exact wording of it in the final few hours of inter-governmental review of the “Summary for Policymakers”. Several oil states objected to any language that put a fixed limit on our total carbon budget. The compromise was to give several different targets for different levels of risk.

Let’s unpick them. First notice that the targets in the first sentence are based on looking at CO2 emissions alone; the lower targets in the second sentence take into account other greenhouse gases, and other earth systems feedbacks (e.g. release of methane from melting permafrost), and so are much lower. It’s these targets that really matter:

• To give us a one third (33%) chance of staying below 2°C of warming over pre-industrial levels, we cannot ever emit more than 880 gigatonnes of carbon.

• To give us a 50% chance, we cannot ever emit more than 840 gigatonnes of carbon.

• To give us a 66% chance, we cannot ever emit more than 800 gigatonnes of carbon.

Since the beginning of industrialization, we have already emitted a little more than 500 gigatonnes. So our remaining budget is somewhere between 300 and 400 gigatonnes of carbon. Existing known fossil fuel reserves are enough to release at least 1000 gigatonnes. New discoveries and unconventional sources will likely more than double this. That leads to one inescapable conclusion:

Most of the remaining fossil fuel reserves must stay buried in the ground.

We’ve never done that before. There is no political or economic system anywhere in the world currently that can persuade an energy company to leave a valuable fossil fuel resource untapped. There is no government in the world that has demonstrated the ability to forgo the economic wealth from natural resource extraction, for the good of the planet as a whole. We’re lacking both the political will and the political institutions to achieve this. Finding a way to achieve this presents us with a challenge far bigger than we ever imagined.


You can download all of Climate Change 2013: The Physical Science Basis here. Click below to read any part of this series:

  1. The warming is unequivocal.
  2. Humans caused the majority of it.
  3. The warming is largely irreversible.
  4. Most of the heat is going into the oceans.
  5. Current rates of ocean acidification are unprecedented.
  6. We have to choose which future we want very soon.
  7. To stay below 2°C of warming, the world must become carbon negative.
  8. To stay below 2°C of warming, most fossil fuels must stay buried in the ground.

Climate Change 2013: The Physical Science Basis is also available chapter by chapter here:

  1. Front Matter
  2. Summary for Policymakers
  3. Technical Summary
    1. Supplementary Material

Chapters

  1. Introduction
  2. Observations: Atmosphere and Surface
    1. Supplementary Material
  3. Observations: Ocean
  4. Observations: Cryosphere
    1. Supplementary Material
  5. Information from Paleoclimate Archives
  6. Carbon and Other Biogeochemical Cycles
    1. Supplementary Material
  7. Clouds and Aerosols

    1. Supplementary Material
  8. Anthropogenic and Natural Radiative Forcing
    1. Supplementary Material
  9. Evaluation of Climate Models
  10. Detection and Attribution of Climate Change: from Global to Regional
    1. Supplementary Material
  11. Near-term Climate Change: Projections and Predictability
  12. Long-term Climate Change: Projections, Commitments and Irreversibility
  13. Sea Level Change
    1. Supplementary Material
  14. Climate Phenomena and their Relevance for Future Regional Climate Change
    1. Supplementary Material

Annexes

  1. Annex I: Atlas of Global and Regional Climate Projections
    1. Supplementary Material: RCP2.6, RCP4.5, RCP6.0, RCP8.5
  2. Annex II: Climate System Scenario Tables
  3. Annex III: Glossary
  4. Annex IV: Acronyms
  5. Annex V: Contributors to the WGI Fifth Assessment Report
  6. Annex VI: Expert Reviewers of the WGI Fifth Assessment Report

10 Responses to New IPCC Report (Part 8)

  1. grendelkhan says:

    Very well put. Thank you for the explanation,

    The thing is, it won’t even help if people virtuously try to use less energy (cutting down demand); if they do, the prices will marginally drop and others will consume more; the efficiency of the market will be our undoing.

    So the only two possible solutions appear to be to distort the market so that extraction is uneconomic (get everyone to sign onto a carbon tax or the like), or to come up with energy sources which are cheap enough to make it uneconomic to dig up the carbon. (People are really trying on that one.)

    It’s quite a pickle. Every problem we have is generally solved by acquiring and using more resources. But what happens when that mechanism is precisely what will doom us?

  2. I don’t see the political will to adopt renewables – in fact, events are going the opposite way – there are quite a few other states with similar legislation to this: http://stateimpact.npr.org/oklahoma/2014/04/21/solar-and-wind-surcharge-bill-passes-legislature-awaits-governors-signature/

    • nad says:

      @streamfortyseven

      Unfortunately I couldn’t figure out from the article you linked to whether you would need to pay that charge, even if you don’t sell anything back to the grid or not.

      Here in the April 21st article it does sound as if you need to pay even if you don’t use it:

      A legislative measure that would allow electricity utilities to charge higher rates to customers who generate electricity with small solar installations or wind turbines has passed an Oklahoma House committee and now awaits Gov. Mary Fallin’s signature.

      Here it sounds as if no:

      April 1st

      The utilities say small electricity generators need to pay to use the electric grid itself.

      But if no, why are the grid costs not included in the selling price?

      • They both say the same thing, presumably if someone is a customer of an electric utility, their power system is tied into the grid – i.e. has a physical connection to it. Now, in your first example you state something not in evidence: “it does sound as if you need to pay even if you don’t use it.” If they’re connected to the electric utility, while they may be pushing power on to the grid at some times, at others they may be using grid power. If they’re always pushing power onto the grid, what’s the point of that? Why don’t they just disconnect, and store the power, or generate less? That’s the solution here, I think. Of course, at least in the US, the government is controlled by the large corporations which use it to maximize their profits. The only real solution to that is to get rid of as much of the government as you can possibly manage to do.

        • nad says:

          They both say the same thing, presumably if someone is a customer of an electric utility, their power system is tied into the grid

          This “Presumably” is what I wanted to turn into a more definite form.

          So again: does one have to pay if one is completely disconnected yes or no?

          I should point out that I am not interested enough in Oklahoma’s tariffs that I would start to go through Oklahomas legal texts (if those are available at all). It seems there are similar things going on in Germany and I get already goose flesh if I think that I might need to go through the corresponding legal regulations. So somehow I can understand that the Oklahoma journalists where also hesitating to do so and most customers won’t disconnect anyways….at least not if the tariffs are not getting too bad.

          Why don’t they just disconnect, and store the power, or generate less?

          One could do this if one produces enough electricity, i.e. equal or more than needed. I suppose that the current stage of tariffs it would though probably be more costly for the ones who disconnect now, because they have to fund first extra storage solutions (like electric cars, batteries, shredders in farming etc.) If intermittent power generation gets more the grid will in the near future also need to pay more for better storage solutions but this independency of customers would be for the grid less good (in terms of energy generation), because the grid would loose the “excessive” electric energy which had been previously fed in.

          Concerning the price: Usually the “grid storage” price is implicitly somewhat contained in the feed-in price. That is if I have an extremely inflexible form of power like for example from a nuclear power plant which one can’t ramp up as fast as like say a gas plant then one can’t for example get the presumably high prices (??) of peak power a.s.o. So the feed-in tariffs are probably calculated with respect to average solar peak hour currency prices plus possibly some political incentive or so?

        • nad says:

          So again: does one have to pay if one is completely disconnected yes or no?

          by the way if yes there are some subtle extra questions, like what is the tariff if the solar energy is used for animals and especially for plants only.

        • John Baez says:

          So again: does one have to pay if one is completely disconnected yes or no?

          This article says:

          Anyone living in Oklahoma planning to power their home using a rooftop solar panel will soon be charged a fee for the right to do that while still being connected to the local power grid.

          Now, reading this as a mathematician, I can’t conclude anything about what happens if I’m not connected to the local power grid. But reading it as an ordinary person, I’m 99% sure they mean you’re not taxed if you’re not connected to the local power grid. And that’s good enough for me.

          If you want more information, you can read the law. I know you said you don’t want to. I don’t want to either.

        • nad says:

          I was quickly digging through the amendments (couldnt find the final version)

          there a socalled “distributed generation” is defined as

          a)
          a device that provides electric energy that is
          owned, operated, leased
          or otherwise utilized by the customer

          b)
          is interconnected to and operates in parallel with the
          retail electric supplier’s grid and is in compliance
          with the standards established by the retail electric
          supplier

          So this sounds as the charge is only for the grid connected.
          and the charge is not only for solar.
          but retail seems to be excluded:

          e)
          does not include generators operated and controlled by
          a retail electric supplier,

  3. Jon Rowlands says:

    The concluding paragraphs argue that even abundant renewable energy won’t stop us from burning all the fossil fuels we can find. It’s hard to avoid the implication that geoengineering must be part of the solution. The almost-final IPCC WG3 report on mitigation covers sequestering and afforestation a little, but from my light reading doesn’t emphasize it. Are there any realistic options on a scale that would help? Are any climate models up to the task of evaluating geoengineering options?

  4. Raymond Lutz says:

    Hmm, does the plotted temperature anomalies include the effect of methane feedback?

    I read “Limiting the warming caused by anthropogenic CO2 emissions alone” in the Summary for Policymakers excerpt but then “when accounting for non-CO2 forcings as in RCP2.6”.

    Well, as I’m typing this comment, I Googled for the answer and here it is:

    no, “The RCPs are projected from CO2 alone – they do not include the other GHGs”

    http://www.climateemergencyinstitute.com/ipcc_ar5.html

    So… it restricts even more our carbon budget. +2C is a dream.

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