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Modelling the permafrost carbon feedback

Posted on 4 October 2012 by Andy Skuce

A recent modelling experiment shows that climate change feedbacks from thawing permafrost are likely to increase global temperatures by one-quarter to a full degree Celsius by the end of this century. This extra warming will be in addition to the increase in temperature caused directly by emissions from fossil fuels.  Even in the unlikely event that we were to stop all emissions in the near future, this permafrost climate feedback would likely continue as a self-sustaining process, cancelling out any future natural draw-down in atmospheric carbon dioxide levels by the oceans or vegetation. Avoiding dangerous climate change by reducing fossil-fuel emissions becomes more difficult once permafrost emissions are properly considered. 

Many papers have looked at the expected contribution of thawing permafrost to climate change. For example, Schaeffer et al. (2011) and Schuur and Abbott (2011) have both published estimates of the effect that the thawing and decomposition of organic matter in Arctic soils will have on future climates. Aspects that these studies neglected were the feedback that the permafrost carbon release would have on causing further permafrost degradation and the varying response that the carbon release would have on the climate in different emission scenarios and for a range of climate sensitivities.

To explore this matter further, a recent paper in Nature Geoscience (paywalled) by Andrew MacDougall, Christopher Avis and Andrew Weaver couples together climate and carbon-cycle models. Using the University of Victoria Earth System Climate Model adapted to include a permafrost response module, the researchers calculated the contribution to climate warming of thawing permafrost over a range of varying parameters.

Figure 1. Taken from MacDougall et al. (2012) showing the additional warming induced by permafrost thawing for four diagnosed emissions pathways (DEP, see text below for explanation). The coloured areas are the ranges of likely additional temperature ranges and the black lines show the median responses. The uncertainty within each DEP run results from uncertainties in the density of carbon in the permafrost and the climate sensitivity (the temperature effect of a given rise in carbon dioxide concentration in the air). Figure with original caption here.


Emissions pathways

The four scenarios or diagnosed emissions pathways (DEP) were derived from the Representative Concentration Pathways (RCP) used for the upcoming Fifth Assessment Report of the IPCC. RCPs are not emissions scenarios but rather curves of atmospheric CO2 concentration with time. The numbers 2.6, 4.5, 6.0 and 8.5, correspond to the radiative forcing in W/m2 in 2100. For use in climate models the emissions scenarios have to be backed out of the RCPs to give the DEPs.

Figure 2. The DEP’s used in the MacDougall et al study. The figure corresponds to Figure S2 in their Supplementary Material. The top graph shows the annual human CO2 emissions pathways and the lower graph the cumulative emissions. The jitter in the top curves is due to variations in solar cycles. Note that the most optimistic curve DEP 2.6 has emissions that drop to zero from 2020 to 2070 and, following that, net human sequestration of atmospheric carbon. The most pessimistic pathway has emissions that continue on their recent trajectory until 2070, when they level off. Roughly speaking, the pathways can be categorized as Heroic (2.5); Prudent (4.5); Procrastinating (6.0); and Oblivious (8.5).

Other variables of the model

a) Size of the carbon pool. MacDougall et al vary the carbon concentration of the permafrost from 15.8 to 26.3 kg/cubic metre, which leads to a range of 837-1206 PgC (billion tonnes of carbon) for the upper 3.5 metres of permafrost. This figure is larger than that assumed in previous studies. Consequently, the upper-end range of carbon release by 2100 calculated in this paper, 508 PgC, is much larger than the previous studies that did not use coupled carbon-climate models. For example, Schaeffer et al calculated 138 PgC as their upper limit. The entire permafrost soil carbon pool is estimated to contain 1700 PgC, about twice the mass of the carbon in the current atmosphere.

b) Climate sensitivity. The other important variable used in the model is the climate sensitivity, which varies between 2.0 and 4.5°C for a doubling of atmospheric CO2, with a central value of 3.0°C.

Counter-intuitive results

The results shown in Figure 1 are very consistent for the 2100 median forecasts, ranging between 0.23 and 0.27°C of extra warming due to permafrost feedbacks. By 2300, the range of median has increased to 0.37 to 0.73°C. The results are a little counter-intuitive, with the biggest feedbacks in temperature terms not coming with the worst emissions pathways. On one hand, the amount of permafrost carbon released on the most pessimistic pathways is larger (39, 58, 67 and 101 ppm CO2 respectively for the four DEP’s), and occurs sooner. On the other, in the lower DEP cases, the permafrost carbon released to the atmosphere has a stronger effect due to less saturation of the infra-red absorption bands.

Also counter intuitively, the uncertainty of the permafrost feedback is reduced in the higher emission scenarios. In these scenarios, there is less uncertainty that we will unleash all of the permafrost, and quickly. Not only that, but following the pessimistic pathways means that we will have already have inflicted so much violence on the atmospheric chemistry that the extra damage caused by the permafrost feedback will be felt relatively less strongly.

The industrial shutdown experiment

The results in Figure 1 imply that we are in for at least some backlash from the permafrost whatever emissions pathway we choose to follow. Because the real world will resemble a coupled climate-carbon cycle model, the releases of permafrost carbon will result in more warming, which will cause still more carbon to be released. In other words, at some level the cycle will become self-sustaining, even without any further human encouragement. MacDougall et al investigated this by imagining a complete shutdown of human emissions in 2013 and in 2050.

Figure 3. Showing the atmospheric concentration of CO2 following a shutdown of human emissions in 2013(left) and, after following DEP 8.5 for 39 years, a shutdown in 2050 (right). The dotted blue line shows the results at a climate sensitivity of 3.0°C and the upper and lower lines 4.5° and 2.0° respectively. Selected and modified from Figure S8 in the Supplementary Information.

What Figure 3 demonstrates is that even in the case where human emissions cease altogether, the atmospheric CO2 concentration will remain more-or-less constant in the most likely climate sensitivity case. Essentially, for a climate sensitivity of 3°C, the self-sustaining permafrost-related emissions match the uptake of CO2 from the oceans and the terrestrial biosphere. Note that a self-sustaining feedback is not the same thing as a runaway greenhouse effect.

Permafrost feedbacks and the trillionth tonne

Allen et al (2009) argued that what matters most in determining safe levels of emissions is not so much the rate but the cumulative amount. Framed in this way, total emissions of a trillion tonnes of carbon will lead to a most likely warming of 2°C, a somewhat arbitrary, but widely accepted limit on the amount of warming that the world can endure without a high risk of catastrophic consequences. According to the website, humans have already emitted 561 billion tonnes of carbon from fossil fuels, cement production and land use changes. We therefore have about 440 billion tonnes left to emit before we cross the trillion tonne limit. On present emission trends, this will occur in 2043.

MacDougall et al predict median permafrost emissions of 174 billion tonnes of carbon by 2100, which are more-or-less independent of the future pathway of our other emissions. Such feedbacks were not factored in to the trillionth tonne analysis, or were assumed to kick in after the "safe" limit of 2°C had been breached. Accordingly, the 440 billion tonnes we can still emit over the next few years and stay under the trillion-tonne limit needs to be reduced from 440 to 270 billion tonnes of fossil fuel, cement and land use emissions, a reduction of some 40%. Avoiding dangerous climate change becomes a lot harder once we face up to the permafrost feedback.

Why even this bleak prospect may be optimistic

Alert readers may have already noticed that this article has not yet used the word “methane”. When organic matter in the permafrost is thawed and decomposes it produces mostly CO2 but also small amounts of methane, particularly so in the wetlands that are prevalent in areas of thawing permafrost. Schuur and Abbott (2011) polled 41 experts on permafrost decay who estimated that about 3% of the carbon released from the permafrost will be in the form of methane. Methane has a restricted lifetime in the atmosphere, measured in decades, but while present in the air it has a greenhouse effect some 25 times that of CO2 over a 100-year period and higher values over shorter periods. According to Schuur and Abbott, the small amount of methane is responsible for approximately half of the warming effect from the permafrost emissions.

The UVic model does not simulate methanogenesis. That is to say that it does not model the generation of methane—all of the permafrost carbon that goes into the atmosphere in the model is in the form of CO2. This is a significantly conservative simplification over the time period studied.

Also, their model assumes only purely thermal degradation of the permafrost. Physical erosion, for example at coastlines, is not considered. Their model accounts only for permafrost down to a depth of 3.5 metres and there is plenty of carbon stored below those depths that was excluded from their modelling.

Finally, this study does not consider any contribution of methane from methane hydrates, either from under permafrost or under ice sheets, nor from fossil methane currently trapped under an impermeable seal of continuous permafrost.


  • Thawing permafrost will release carbon to the atmosphere that will have an appreciable additional effect on climate change, adding at least one quarter of a degree Celsius by the end of the century and perhaps as much as one degree. (In comparison, Swart and Weaver (2012) calculated that combustion of the in-place resources of the Alberta oil sands would increase temperatures by 0.24-0.50°C.)
  • The temperature effect of the coming permafrost feedback is not sensitive to the emission pathway that we choose to follow.
  • The permafrost feedback response to our historic emissions, even in the absence of future human emissions, is likely to be self-sustaining and will cancel out future natural carbon sinks in the oceans and biosphere over the next two centuries.
  • Unfortunately, there are several good reasons to consider the outlook in MacDougall et al. as rosy; as the authors themselves make clear. However, as bad and inevitable as they are, feedbacks from the permafrost are just the (de-)icing on the fossil fuel cake that we are busy baking. It is still up to us to infuence how severe climate change is going to be.

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Comments 1 to 40:

  1. Very interesting, thanks Andy. A few questions spring to mind: 1. If I understand correctly, the permafrost feedback isn't in CMIP3 climate models, so on this basis they are probably underestimating climate sensitivity. Is it in the CMIP5 models? (I'm guessing some of the the earth-systems models do take this into account.) 2. However long term sensitivity estimates based on past climate (in particular the glacial cycle) should already include this effect? 3. The authors attribute the reduced additional temperature impact of thawing under the highest emission scenarios to saturation of the IR bands. Presumably there is also an effect due to the logarithmic CO2-forcing relationship, but looking at the numbers I'm guessing this is a weaker effect?
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  2. Its impressive they found a way through the morass of interlinked variables to get a result! So no amount of tinkering at the edges - changing drainage, encouraging healthy moss, grazing , allowing forest to grow, even gm moss with extra tannins - will make any difference? I still cant help seeing those vast peatlands of siberia as a massive waiting resource for sequestrTion and to grow our meat once brazil is a desert... Interesting snippet - the chap that described the enzymatic latch mechanism ( chris fellows of bangor) is doing the gm thing: He also mentions on his own site the possibility of more drying due to our new pattern of rubbish jert stream with many blocking highs which would increase loss from fire and oxidation ho hum
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  3. I have a similar question to that of Kevin C. I would have thought that the logarithmic relationship IS the saturation effect. It seems to me in that case that the DEP 8.5 case would only be slightly higher than the DEP 6.0. Instead, it's actually lower. Perhaps you address this point again.
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  4. Andy, An issue that I am sure will be brought up questioning the total numbers on projected warming. There has been a lot of alarm (and some wild claims) regarding the CH4 emissions from the ESAS as observed by the Russian researchers and others. Since the paper does not take those emissions into account, nor these
    "Finally, this study does not consider any contribution of methane from methane hydrates, either from under permafrost or under ice sheets, nor from fossil methane currently trapped under an impermeable seal of continuous permafrost."
    There seems to be quite a few potentially significant methane emissions still to take into account. One would have to assume that the warming estimates in the above paper are very conservative still. Are you aware of any rigorous effort to provide a comprehensive estimate on total emissions (of all kinds at all locations) and projected warming. Recently there was a post on RealClimate regarding CH4 emissions, but it did not take into account any of the above either. There are a lot of people who are really interested in a warming estimate that takes all known sources into account. Thanks
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  5. To Answer the Questions of Kevin C: “1. If I understand correctly, the permafrost feedback isn't in CMIP3 climate models, so on this basis they are probably underestimating climate sensitivity. Is it in the CMIP5 models? (I'm guessing some of the the earth-systems models do take this into account.)” The permafrost feedback is not included in any of the CMIP3 or CMIP5 climate models. However, CO2 from permafrost does not contribute to climate sensitivity. Climate sensitivity is defined as “to the equilibrium change in global mean surface temperature following a doubling of the atmospheric (equivalent) CO2 concentration (IPCC glossary of terms)”. This definition specifically leaves out carbon cycle feedbacks. The climate sensitivity is determined by the direct radiative effect of CO2 and feedbacks from non-CO2 systems (ex. albedo, clouds, water vapour). 2. However long term sensitivity estimates based on past climate (in particular the glacial cycle) should already include this effect? The permafrost climate feedback presumably did play a part in glacier-interglacial carbon cycle feedbacks (Ciais Et Al. 2012 doi:10.1038/ngeo1324), and has been hypothesized to be responsible for earlier events in Earth history (DeConto Et Al. 2012 doi:10.1038/nature10929). 3. The authors attribute the reduced additional temperature impact of thawing under the highest emission scenarios to saturation of the IR bands. Presumably there is also an effect due to the logarithmic CO2-forcing relationship, but looking at the numbers I'm guessing this is a weaker effect? The saturation of IR bands is the mechanistic explanation for the logarithmic forcing from CO2. Also contributing to the muted temperature response in the high emissions scenario is the self-limiting nature of the feedback. That is, there is a point beyond which almost all the permafrost has thawed and all the carbon in the permafrost is decaying. At that point further waring will not contribute to a larger feedback.
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  6. Thanks for your participation Mr McDougall. Comments and clarification by real researchers are always greatly appreciated.
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  7. Many thanks to Andrew MacDougall for showing up here and answering those questions. Incidentally, I wrote an SkS article some months ago on the DeConto et al paper that he referred to in his comment.
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  8. Wyoming@4 I am not aware of any climate modelling studies that incorporate future methane hydrate releases. Modelling studies of permafrost feedbacks, such as the one covered in this post, are relatively recent, even though, compared with hydrates, the permafrost carbon is much more easily studied and observed because it on the surface and on land. Also, because hydrates are either buried under great thicknesses of permafrost or hundreds of metres of seawater, they likely will not become destabilized for centuries. In contrast, the response of the top few metres of frozen soils is likely to happen sooner. I'm more inclined to trust the opinions of David Archer than the Arctic Methane Emergency Group, on this issue. Having said that, I'm following the latest research with an open mind and I would very much like to see a modelling exercise that attempts to quantify the size and timing of methane hydrate releases and their effect on the climate. Recently, SkS conducted an interview with researcher Natalia Shakhova, that may be of interest. I'm working on a series of posts on subcap methane releases, which I think may prove to be more immediate in their climate impact than hydrate destabilization.
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  9. Thanks Andy Interesting post pointing again to things having been underestimated by the models previously used to inform decision makers. Looking at figure 1, DEP2.6 the range seems like a lower limit ~0.23C to an upper limit of 0.8C by 2100. That is an additional temperature rise for 39ppm extra CO2. 39ppm is only at most 1/10 of a doubling from 390ppm, so a CS in the model acting as 2.3C. Therefore must presume this a low end estimate, and as CS could just easily be 4.5C (especially considering the skewed distribution of CS), 0.45C is just as likely. And even with complete cessation of CO2 emissions from fossil fuels in 2013 from figure 3, atmospheric CO2 remains the same just to due additional CO2 permafrost releases, so will be at least 390ppm all the way to 2100 even if that impossible extreme occured and that is despite there being strong CO2 sinks maintained in the model, when these do seem at considerable risk when the following are considered; peat drying, forest fires, mangroove degradation, aerobic methane release from the arctic, methane from permafrost world wide (as mentioned above), vegitative diseases (pests, fungus), hotter oceans, increasing weather extremes and mass biodiversity losses. Not sure if SO2 emissions are ceased in the model but many studies have shown that this heating effect is very signifiance at least 0.4C by 2050 if SO2 emissions were stopped today. Add in the heat in the system ~0.4-6C and 2C is an almost certainity even with a CS of 2.3C, and considering recent extreme events, 1.5C is a daunting proposition. The Pliocene, the best past analogy of today, albeit with a slightly cooler sun, suggests 350ppm means a significant climate shift resulting in an Ice free Northern Hemishpere and a much warmer climate with lots more water available for the water cycle, due to the ability of air to hold 8% more water per extra 1C in average temperature (that is a lot of extra water). Also there were wider tropics and a much warmer North Pole, therefore I pressume a meandering, blocking, severe extreme weather inducing jetstream situation and over time 20-25m sea level rise, how quick this will occur is debateable however 2m by 2100 does not look out of the question, and that this a lot of extra shallow tropical seas for storms to brew over. Therefore does any on here feel, that 1 trillion tonnes of CO2 emissions, or bascially adding 80% again of what we already have, is safe?
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  10. Everybody here stipulates the consequences of C cycle disturbance we are causing. The disturbance in measured as just GtC, without actually qualifying the change of C oxidation/stability. What I mean here is that FF burning disturbance is far more severe than permafrost thawing disturbance. Because FF are sequestered in very stable form in 400Ma timeframe. That qualifies as at least 4000 times more stable as permafrost, which was likely thawed/refrozen in 100Ka interglacial cycles. That's why CO2 from FF is "far worse" than permafrost thawing for climate stability. That's why the Earth will have much harder time dealing with FF CO2: i.e. oceans that currently absorb some of it, will eventually degass it. While permafrost down to 3.5m may release CO2 that would eventually be effectively absorbed by the growing biosphere (i.e. lush forests may replace thundra if we return to hothouse) because the C in question is effectively part of the circulation in biosphere. So, when talking about carbon cycle changes, on a long run (that concious custodians of this planet should realy care, beyond 2100 which seams to be a limit of conciousness by politicians) one can ignore the effects of natural C feedbacks (that seem small by this study anyway) and concentrate on human disturbance that is unprecedented in millions of years.
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  11. Thanks Andrew for those answers. I think it'll take me a while to grok the last one; my mental model of OLR clearly isn't sufficiently sophisticated at this stage. (It may of course be one of those things you never really understand till you've implemented your own.)
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  12. I imagine that as the temperature of the permafrost increases so does the metabolism of the methanogens. Microbial organisms are always sluggish at colder temperatures but their metabolism increases (exponentially?) as the soil temperature goes up. Has this factor been considered?
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  13. You all seem to be taking this very well. Look again at the left-hand side of figure 3 and at the section headed: "Why even this bleak prospect may be optimistic." Put those together. What do you get? Unless you think it highly likely that climate sensitivity is well below 3 degrees C for every doubling, combining figure 3 with the section I referenced means that we are going to see _increases_ in CO2 levels even if we stopped _all_ CO2 emissions by _next year_. This is the scenario that many of us have called "run away global warming," and this study basically proves that we are already inside that doomsday scenario. Does this not upset anyone else? Even a little? Am I missing something? Please tell me I am (but also tell me what that is).
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  14. Wili, what I knew before upset me. What do you want me to do? I can't save the world by myself. If I start jumping up and down and wringing my hands, screaming obscenities, I'll get thrown in the nuthouse--figuratively and/or literally. Cultural momentum is more powerful than the sun.
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  15. wili you can be sure that many of us put this results in our "mental “oh shit” folder", to use climatesight's words. We alredy knew about this thawing permafrost feedback but probably not many suspected that the risk of a runaway effect was so near. But then, the rational response to a threat is to stay calm and don't let people panic. However hopeless the situation might be we always have to find the best thing to do, the best possible way out of the mess.
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  16. Riccardo@15 "many suspected that the risk of a runaway effect was so near." Out of my ignorance, what is the definition (and end result) of runaway effect in this case? Is it a planet where the temperature has risen to the degree that the ice caps have melted but the system is stable (in a couple of thousands of years) and may (due to other forcings) decrease, or gone the Venus-way which can no longer sustain any life as we know and will not decrease anymore? The reason I'm asking is that my simple model of various limits, the runaway-option (at least my version of it) is the far end, well beyond ~7000ppm (taken from the historical reconstructions). And just to note that the scenario where we humans move back to the proverbial cave or go even extinct is well before that.
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  17. "However hopeless the situation might be we always have to find the best thing to do, the best possible way out of the mess." (Riccardo,15) Community Adaptation Transformation, aim Peak CO2 400ppm, 350ppm by 2100, change all world civilization systems and functions that need changing to enable that to happen. That means setting a realistic carbon budget (i.e. one where we have ~2-3 years or current emissions left) and therefore means a massive volentry power down as there isn't enough carbon to buy loads of power (renewables all have a large carbon cost), and use or imaginations and creativity to create an equitable world that is sustainable and eco-system enhancing rather than waiting for a techno silver bullet that isn't coming. How carbon is safe to spend on buying energy for the future considering to extreme urgency of the situation? Basically things like renewables are not carbon saving they are a carbon and environmental cost to provide power for 10-30years depending on breakdowns etc. Make the impossible possible by acting now immediately starting at home, i.e. stop flying full stop!?????
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  18. On an old thread I tried to point out that the environment absorbed about 2% of our excess CO2 over some equilibrium which used to be preindustrial, but rises as the temperature rises. One of my comments was here but in the comment that immediately follows, Tom Curtis pointed out that the "50% of annual emissions" was closer to the truth. I tried to answer that in the post following his. Whether I was closer or farther from the truth in that thread (the answer lies between the two extremes) matters to this thread. If the ocean as a system (including turnover) continues to absorb 2% or some significant fraction of CO2 over equilibrium, then CO2 from the Arctic does not matter except as a new source which is currently much smaller than the manmade 9 Gt/year. That new source is projected to increase with various sensitivities (as shown in the graphs) and presumably arctic amplification (not mentioned as a variable above). The fact that we are not about to stop producing CO2 makes my discussion academic however.
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  19. Lanfear I was referring to the melting permafrost feedback. In this case it means that the effect is self-sustaining, that it's beyond the point at which it won't stop (untill there's no more permafrost, of course) even if we cut our emissions. As for the runaway warming you refer to, there's an interesting post by Chris Colose here. Please post there any further comment.
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  20. Lanfearr @ #16--Efforts to avoid panic have left us where we are--adding ever more carbon to the atmosphere every year. Someone said that US (and I would say it hold for the world) policy has two modes--complacency and panic. Complacency is what we have and it has not worked. When rock-solid scientific evidence is in that the world is now in an unavoidable climate death spiral, I would say it is past time to tilt the scale toward panic. We can all, after all, see clearly now that complacency has failed miserably. (Ah, I found the original: "We have only two modes - complacency and panic." — James R. Schlesinger, the first U.S. Dept. of Energy secretary, in 1977, on the country's approach to energy.) To DSL @ #14: We now have rock-solid evidence that the world is in a climate death spiral and your main concern is that people not think you eccentric by your reactions to it?? To ranyl @ #17: Unfortunately, there is no, one, agreed-upon definition of 'runaway' in this case, as far as I know. To me, once feedbacks have kicked in to the extent that, even with total cessation of the original forcing (here, CO2 from human burning of ff, cement production, land use...), the system continues to move in the direction it was forced (toward ever higher levels of atmospheric CO2 and, therefore, ever greater global warming, in this case)-- that is when you have a runaway condition: the momentum of the system has "run away" from our ability to stop it getting worse by stopping the practices that got it started; it has become a self-perpetuating cycle--a death spiral. (This does not, of course, mean that it will run away forever. Eventually--when all the stored carbon in permafrost, methane hydrates, soils and other accessible sources have entered the atmosphere--there will be nothing more to drive the cycle. Of course, by that time, we will have a much, much hotter planet--assuming there is a "we.") For the record, I still think, in fact more than ever, that we must have a crash global program of getting off of fossil fuels immediately, just in case there is some unknown unknown 'negative' (damping) feedback that may come along and save our sorry @$$es in spite of ourselves, if just given the chance. Such a program will, at this very late date, involve massive disruption, suffering, and even death. But, in my book, better to incur limited suffering now in the hope that the worse may be averted eventually, than to continue earth-annihilating behaviors that will absolutely assure total destruction in the (not too distant) future. But perhaps that's just me?
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  21. So, wili, what are you doing? Why are you here talking on the net when you could be out there jumping up and down and looking like a nut? If people outside the science had their opinions shaped by fair representatives of the science, we, as a species, would already be thoroughly engaged in mitigating and robust development of alternative energy. The disconnect in understanding between you and the middle-class junior accountant driving by the corner where you're jumping up and down is enormous. To the accountant, the problem is as serious as CNN thinks it is -- maybe two, minute-long spots per week. What's permafrost? Shrug. To the Wal-Mart manager driving by, you're everything that's wrong with the world, and Rush backs him up (or leads him, if he could see it). I talk to people about this situation face-to-face every day, and my goal is one person convinced per day -- and convinced enough to think about immediate personal and democratic change. Note how many people protested the war on Vietnam. Note how effective it was. Note how many were squashed and became disillusioned. The comparison deserves a more comprehensive analysis, but for the moment I stand by it. If the US population could have been convinced that Vietnam was readying a war machine (or WMDs), the resistance to the war would have been much less significant. People need to be convinced that a direct threat to their way of life is at hand. A specific set of events needs to be in the pipeline. Until then, the postmodern condition rules the day, that condition of being ethically and physically isolated from the consequences of one's economic decisions (except for the bank balance).
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  22. Eric (skeptic) (i) the new equilibrium isn't higher because the temperature is higher as much as because there is simply more CO2 flowing through the active carbon cycle. IIRC, it will stay that way until chemical weathering permanently sequesters all of the excess back into the lithosphere. The Arctic CO2 does matter, as it is substantial compared to the difference between natural emissions and natural uptake, and so will have a substantial effect on the rate at which atmospheric CO2 will rise.
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  23. Eric @ 18 It's not clear to me what your point is. The modelling done by the UVic people fully takes into account the carbon cycle response of the oceans and Arctic amplification, among many other things. Doing our own spreadsheet calculations and back-of-the-envelope calculations can be helpful in terms of learning and understanding, but the results such efforts can't seriously be considered to undermine the conclusions that arise from sophisticated modelling performed by experts and published in distinguished peer-reviewed journals.
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  24. DSL, thanks for your thoughtful response. Without going into too much detail, I have been learning about, teaching about, and doing activism at various levels on GW issues for over 20 years. I really was just looking for someone here at least saying that this was a 'holy sh!t moment' for them as it was for me, and as it is for the host and most posters at ClimateSight, the other site that seems to be discussing this article in some depth. Since we both seem to work face to face with people on this issue, I would be interested to know if you have seen any shifts in people's perceptions of gw in the last few years. I see less resistance to discussing it among college students, but this may be due to changing views of how to interact with perceived authorities. I constantly struggle with the question of how to present these issues, as they get more and more grim, to others, so any insights you have would be most welcome. I think people need to start hearing some alarm in peoples voices that speak about it, or they will assume that, if the people who know about it don't seem alarmed, they needn't be either. Of course, there is always a possibility, probability that some/most people will reject the message and/or the message no matter how you present it. Search "ethos, pathos, logos" for discussions of how to match the tone of what you are saying with the information you are conveying.
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  25. wili When I first read this paper, I had my own "oh shit" moment, which prompted me to write this article. I felt that the results need to be made accessible for people who don't have access behind the Nature pay wall. As you acknowledge, it's difficult when writing about matters like this to get the tone right. The objectivity of the article could be marred if too much subjective emotion is included. On the other hand, if it's just a recounting of dry facts, the real message might also be lost. Also, balance is required in conveying an appropriate degree of alarm, without creating an impression that everything is out of our control and resistance is therefore futile. With a diverse audience, it's impossible to get the tone right for everyone. But that's one good reason why comments threads are important, so that readers can provide their own impressions, as you did. Thanks.
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  26. Dikran, thanks for the information. I agree that Arctic CO2 will matter at some point. Andy, all I am saying is that nature is a hefty net absorber at the moment. The simplest spreadsheet can show the present, although it can only account for net amounts (e.g. the Arctic could be releasing more and some other location absorbing more temporarily and I would not know that). So if we performed the academic thought experiment of stopping CO2 emissions today, the Arctic is being offset elsewhere today and nature would immediately draw down atmospheric CO2 perhaps 1 or 1.5 ppm per year pretty much independently of other factors (e.g. sensitivity)
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  27. Thanks, Andy S. I think you hit the tone about right for this blog. I was really mostly surprised that there were no "Oh shit" responses yet from any of the commenters so far. We are all greatly in your debt for bringing this to a larger audience than has ready access to complete Nature articles. I see that it has been picked up by Climate Progress, Climate Central, ClimateSight, tamino's blog, and in the comment sections of some other blogs (and I've probably missed some). Unfortunately, even all these are basically a rather closed group. How do we most effectively get this out to the broader public and to decision makers? This should be the clarion call for immediate and (what in other circumstances might be seen as) drastic action on a global level to halt un-sequestration of further carbon, and to rapidly scale down our collective footprint in the most humane, equitable way possible. So do we go to the UN? To congress, local officials? NGO's? Corporate big wigs? Major media outlets? Other sources of power and influence? What next? Erik, read the article again. The study directly disproves your final claim. Are you just spouting stuff you want to believe? Or do you really want to engage with the facts as they are presented to you?
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  28. Wili, my personal "Oh, Shit!" moment came years ago. The sum of the trajectory we have coursed for ourselves by our fossil fuel emissions, coupled with the ongoing demise of the Arctic sea ice (a visual symptom) and the thermal inertia of the oceans painted an outcome which was altogether undesirable for my children and grandchildren (to be, hopefully). So I put myself to work here at SkS, helping others much more talented than I (both in the SkS and climate science community) to help raise awareness of the extremis we find ourselves in. My personal opinion is that, pending a global reconstitution of our ways of living, is that we're screwed. The optimist in me refuses to give in to that, however.
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  29. I can't say I've ever had a specific "oh shit!" moment in climatology - I've been studying it since the late 1970s, from undergrad through grad and faculty positions, and on into post-academic climate research. My "oh, shit!" moments tend to be reserved for the extremes from the denialosphere, but I refuse to place them in the "climatology" or "climate change" category, because they aren't. Daniel: an optimist believes that we live in the best of all possible worlds. A pessimist fears that this is true...
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  30. will, nature is currently a hefty absorber of CO2, therefore any study cannot correctly project increased CO2 from Arctic outgassing or any other source if we stop.. However because we are not going to stop producing CO2 tomorrow, that part of the study does not matter. What matters is that we will continue BAU and we will eventually reach the point where Arctic outgassing will become a major if not dominant factor. There's some uncertainty in the timing and the amounts and I have not studied permafrost thawing enough to say anything really useful. If I could change one thing in the OP, it would be to add some description of assumptions and conclusions regarding Arctic amplification and its effect on permafrost. I'd also like a non-paywalled paper, I buy some papers but I don't have an unlimited budget.
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  31. My "oh shit!" moments come when I talk with my in-laws. They are solid middle-class, Southern US, Leave it to Beaver types. Everyone who works hard (making other people work hard) deserves two cars, 3000 sq ft. of poorly insulated but beautiful home, lots of air travel, and a wide variety of local, regional, national, and international food choices. Take any of that from them, and you take their Freedom. They will not talk with me any longer about the issue. I had a freak out on them at a family gathering. I laid it all out. Some wandered away. A few gave me the Rush Limbaugh lines. Some grinned dissonantly at me. Who knows, maybe that rant is still resonating. Yet every time I visit them, I see the same old same old high-energy choices -- the attempt to live the "good life" (composed of a series of bucket list products). I see that momentum steamrolling right along, and I think, "oh shit." The college students with whom I speak are, for the most part, concerned, and at a highly-selective liberal arts (though public and not that small) university that's not surprising. However, pushing it to the level of "really f_____ concerned!" is difficult, because they're also thinking about jobs. Some have the vision to see that life is not stabilized when one has all four limbs on the career ladder. Most see employment as a kind of womb, protective and distracting. I've had very good conversations with some of these students, and they get it. Some want to get a job working directly on the problem. It just takes a lot of work to re-train oneself from the typical high school experience. It takes a lot of work to live more simply -- not physical labor, but hard mental and cultural work. When your friends and family look at you like an oddball, it's not easy to shrug off. I can make it look easy, but it's not easy.
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  32. DSL, I could not have said it better. My experience exactly. But I consider my family extremely smart, concerned, activist...but they still have the same set of assumptions as to fundamental right to fly to wherever they can afford to go etc... I pretty well alienated myself from them when I opposed my mother's plans to set up an annual family reunion of a very far flung (around the world) family. Let's just say that, in an extended family that usually makes much of each and every birthday, that year I spent my 50th alone with a bottle of scotch. (My immediate family was traveling, too.) I have had at least one student tell me that my presentations of climate facts radically altered his plans--last I heard he was working with a city-wide bicycle rental group. Yes, the heavy lifting is mental and cultural. The brutal facts of climate reality is part of it. The novel "Ishmael" seems to help some to realize deep assumptions and start to question them. But mostly, I feel as if I have utterly and totally failed to communicate anything effective to pretty much anyone. It gets to be hard to know what is worth doing or saying at some point...even what is worth refusing to do or say. At this point, I think I'll just pretty much start screaming at everyone all the time till they put a bullet through my head. Anyway, thanks for all the fish.
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  33. Eric (skeptic) wrote "will, nature is currently a hefty absorber of CO2, therefore any study cannot correctly project increased CO2 from Arctic outgassing or any other source if we stop." This is nonsense; the uptake of CO2 by the natural environment is governed by the laws of physics, and those same laws will continue to apply if we stop emitting CO2. As to buying papers, given the lack of basic understanding of the carbon cycle you have already demonstrated on this thread (c.f. my previous post), you would be better of buying some books on the basics, David Archer's primer is a good start.
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  34. Dikran, we have emitted CO2 into the atmosphere far in excess of equilibrium. Nature is absorbing roughly 1/50th of the excess. If we stopped (again I must caveat, completely academic because we are not stopping), then the situation has not changed. We will still have manmade CO2 in the atmosphere far in excess of equilibrium and nature will still absorb roughly 1/50th of it. As you pointed out in your first reply to me, there is now a higher flow of CO2 from new sources, mainly Arctic outgassing. That flow will increase with thermal inertia. What that means is that the nature will absorb less than 1/50th into the future. I don't know how much less. There are a lot of factors involved (e.g. continuing Arctic amplification).
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  35. Eric (skeptic) as I have pointed out to you before, the constant proportion taken up by the environment is a result of anthropogenic emissions rising roughly exponentially, it is not a natural law. The carbon cycle can only be roughly approximated as a first order differential equation (implied by your 1/50th assertion). In reality, the carbon cycle is more complex than that, and such simple "spreadsheet" models are useful for qualatative understanding of the very basics, but nothing more than that, especially not quantative analysis.
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  36. wili @32 "Anyway, thanks for all the fish." I seem to remember that preliminary to that, there was some sort of guide that prominently said "Don't Panic" on it. To me, SkS is exactly that sort of guide. Best wishes, Mole
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  37. Riccardo@19 "I was referring to the melting permafrost feedback." Ah, yes, then I do agree with you. Sorry for the confusion. With regards to Colose writing, this is largely my understanding too, as there is a whole spectrum of more probable outcomes between what we have now what constitutes a global 'runaway', which I tried to convey in my previous writing (english not being my primary language). wili@20 "Efforts to avoid panic have left us where we are" Again, this may be due to difference in what panic means, but I feel strongly that panic is the least helpful state that people should be in in this (or any) situation, and it seems that this is somewhat reflected in the writings of other people too. Panic IMHO means that individuals throw out their reasoning and goes into a short-circuit mode where the survival instinct rules, resulting in a quick and painful collapse of the society. Nothing can be accomplished in this mode. As a background reference, I am talking as an avid diver and aspiring cave diver where panic equals death. What I would solicit instead is a (rude) wake up call, not much unlike the Samuel L Jackson video 'Wake the f*ck up' backed up with numbers (like what Clinton did). The other part should be a (again rude) confrontation and stripping of any perceived validity of the denialosphere argumentation (maybe in the spirit of Christopher Hitchens). This is why I personally enjoy SkS, but it grieves me that the noise of the lukewarms as well as denialists are assumed by the public as 'equal'. A misanthropist would perhaps think that we deserve what is coming...
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  38. Lanfear english is not my first language either, so there is the concrete possibility that I was not very clear. :) Anyway, we should always be carefull when using the word "runaway" because, as you noticed, it may mean similar but different things.
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  39. Thanks to all who posted here and to Andy S for bringing this to our attention. I don't want to get off topic on the "panic" thing, but the image you have to have of the American public and of our decision makers is one of what is known as a "couch potato"--someone who spends all day on the couch drinking beer and watching TV. The only think likely to wedge such a creature from its perch is the perception/understanding that his house is on fire. Anything short of that will just be passed off as something he can get to later. Once panic gets him up and moving, that will be the time for him to come to some coherent plan. But voices telling him "the smoke coming from the next room probably isn't going to threaten you any time soon" are not going to motivate any action. Again, the reality of how policy responds (according to Schlessinger who spent his life working in these areas at top levels) is that the only actual alternative to at least a bit of motivational panic is complacency, which is pretty much what we've had. If proof (or at least strong evidence) that we have passed into a runaway greenhouse world--which I take this article to be, and I have not so far seen anyone argue convincingly otherwise--isn't cause for some strongly motivational panic to get us and our leaders off of our collective couches, I don't know what will be, besides utter collapse, at which point it will really really be too late. Best, and thank again to all. wili
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  40. It's too bad this important work has not gotten any more commentary. I am using the MacDougall et al work as a starting point to estimate atmospheric CO2 and temperatures for public presentations and for my climate science students.

    The new CMIP6 models are have half their models above ECS=5C, and the work of Friedrich et al  2016 also shows interglacials have ECS=4.9C. And, a nice review paper by von der Heydt in 2016 also shows convincingly that researchers see that ECS is higher in hotter background climates. This all spells a very bad situation of ECS=5C should be our base case and 3C a tail-on-the-optimistic side now. With 2.3% of permafrost carbon emerging as methane and a ~doubling of GWP that results, then the CO2e that then ends up on the MacDougall plots go up to 800 ppm by 2300, and more if the new radiative forcings calculated for methane (better short wavelength calcs) are to be accepted. This all suggests that even if we shut off all human emissions in 2050, we still cook ourselves at over 8C, sooner rather than later in the next two centuries. An 8C world is not survivable except for a minority of today's population, and most of today's other species too. GeoEngineering on a massive scale seems absolutely required, regardless of the moral hazard. Is there something more hopeful that I'm missing??

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