Climate scientist: “Positive carbon-climate feedback is still very likely” — and even without “a runaway feedback,” warming will be “substantial and critical”

Plus a review of recent research on amplifying feedbacks

As the United States, like much of the rest of the world, bakes in record, killer heat, climate scientists continue to refine our understanding of the dire future of global warming in the years to come. The United Nations has named the 831 scientists who will author the fifth Intergovernmental Panel on Climate Change report, to be published in 2013 with new model runs and observations of the ongoing destruction of our habitable environment.

They do this work despite the endless assault from the fossil-fueled right wing, weathering death threats and media and politicians who ignore, downplay, distort, or lie about the science.  Brad Johnson has yet another instance of this criminal deception (with an addendum by JR reviewing the recent literature on feedbacks).

The First Post, a website of Great Britain’s The Week run by Tim Edwards, has claimed that new climate research from the Max Planck Institute for Biogeochemistry “is set to rock the boat again.” Edwards’ headline, promoted by climate disinformer  Marc Morano, blares:

‘Runaway climate change’ ‘unrealistic’, say scientists

“Climate change skeptics might say the new study is yet another nail in the coffin of the IPCC report,” Edwards writes.

His headline and fevered speculation was based on a quote from the Max Planck researchers’ press release, which quoted Max Planck scientist Markus Reichstein saying, “Particularly alarmist scenarios for the feedback between global warming and ecosystem respiration (CO2 production) thus prove to be unrealistic.”

Via Twitter, Tim Edwards defended his piece as a “balanced story about an interesting development in climate change science.” However, by giving credence to conspiracy theorists who believe that mainstream science is a fraud, Edwards utterly misrepresented the research, which was published in a pair of papers in Science.

The researchers’ work in reality reduces uncertainties about how ecosystems respond to changes in temperature, precipitation, and solar input with respect to the carbon cycle, and will be very useful for improving the resolution of global climate models. Far from being “yet another nail in the coffin of the IPCC report,” this research is yet another building block in the vast edifice of climate science that underlies the IPCC work.

In an email interview with the Wonk Room, Dr. Reichstein excoriated the First Post story as a “very bad report,” saying that his research does not show that runaway climate change is “unrealistic.” In fact, Reichstein told the Wonk Room that “positive carbon-climate feedback is still very likely.”

This is indeed a very bad report about our research, strongly misinterpreted and with a unnecessarily sensational tone. In particular the statements in relation to the IPCC report are exactly opposite to what I said (and what is correctly reported in other newspapers). The 4th IPCC report is not challenged at all by our study, because it does not contain “alarmist” scenarios at all. On the contrary, the simulations therein still do not contain the carbon cycle feedback.

Our point is that now for the next IPCC report models are including this feedback and they are doing this in very different way, for example also with different temperature sensitivities. This will lead to a relatively large range of model predictions, a range which can hopefully be reduced by using our data for model improvement.

Reichstein’s research makes the speculative scenario of a feedback loop between warmer temperatures and faster CO2 production from plants less likely. However, as he explained to the Wonk Room, there are many other feedback loops that could give rise to runaway warming:

There are enough other feedbacks which are not touched in our studies. These include permafrost melting and subsequent CO2 and CH4 release to the atmosphere. The positive carbon-climate feedback is still very likely.

The IPCC Fourth Assessment Report’s predictions of climate catastrophe exclude these runaway feedback scenarios. “Even without a runaway feedback via the carbon cycle,” Reichstein said, agreeing with the IPCC assessment, “the warming will be substantial and critical.”

— Brad Johnson

Cross posted from Wonk Room.

The rest of this post is by Joseph Romm.

Here’s some of the recent research and observation on  the dangerous positive carbon-cycle feedbacks that threaten to amplify the impacts of human-caused GHGs.

Indeed, the best evidence is that the climate is now starting to be driven by amplifying feedbacks, most notably:

Using the first “fully interactive climate system model” applied to study permafrost, the researchers found that if we tried to stabilize CO2 concentrations in the air at 550 ppm, permafrost would plummet from over 4 million square miles today to 1.5 million. If concentrations hit 690 ppm, permafrost would shrink to just 800,000 square miles:


The term “runaway feedback” is ill-defined in any case.  I think the more plausible scenario is simply that if we cross a key threshold for any extended period of time, certainly 450 ppm and possibly 400 (or lower), the amplifying feedbacks will accelerate and gravely complicate any effort to constrain emissions.

Even models that don’t fully account for (or even ignore entirely) the amplifying feedbacks we know are the most likely — like the tundra —  show catastrophic outcomes if we don’t get off our current path of unrestricted greenhouse gas emissions:

Few detailed studies have been done of the scenario with high emissions and high positive feedbacks.  One recent analysis makes clear it ain’t pretty:

This is the “plausible worst case scenario” for 2060 from the UK Met Office that occurs in 10% of model runs of high emissions with the carbon cycle feedbacks [temperature in degrees Celsius, multiple by 1.8 for Fahrenheit]:

Graphic of chnage in temperature

The time to act is most certainly now.


17 Responses to Climate scientist: “Positive carbon-climate feedback is still very likely” — and even without “a runaway feedback,” warming will be “substantial and critical”

  1. MapleLeaf says:

    Dear Joe,

    Thanks for this post. The deniers are of course spinning this and distorting as per usual.

    IMO, and I happen to have some expertise int his area, is that their findings highlight the sensitivity of crops and forests (less so for the latter) to water limitations. That is not good news. Specifically, in their press release the researcher state:

    “From a global point of view, however, water is the factor which has the strongest effect: over 40 percent of Earth’s vegetated surface plants photosynthesize more when the supply of water increases, and less during droughts. In temperate grasslands and shrublands, the amount of carbon dioxide which plants fix as sugar depends to 69 percent on their water supply, in the tropical rain forest this figure is only 29 percent.”

    Which leads him to say “Here, too, we need to therefore critically scrutinize the forecasts of some climate models which predict the Amazon will die as the world gets drier.”

    So thankfully the Amazon, at least at those locations they took measurements and in terms of CO2 sequestration, may not be as susceptible as once thought.

    Markus Reichstein goes on to state that “It is still not possible to predict whether this attenuates the positive feedback between carbon dioxide concentration and temperature”.

    Note, is saying that there is a positive feedback, they are just not sure yet whether or not these new data suggest that the positive feedback will be muted.

    Other reason for concern is that “Sixty percent of the carbon dioxide which plants globally take up from the atmosphere is swallowed up by the tropical rain forests and savannahs.”

    So we had better go to greater lengths to preserve these biomes, because deforestation and land-use change could mean that even more anthro CO2 is retained in the atmosphere as the planet continues to warm.

    This study is an excellent example of science at work and how scientific understanding advances. This work will be incredibly useful for constraining and improving AOGCMs (climate models) which incorporate the carbon cycle.

    And let this not distract from the very well understood and much more serious consequences of the positive water vapour feedback.

  2. paulm says:

    “…criminal deception”

    I am glad that we are now starting to refer to this despicable behavior in the light of what it really is.

    Can we not start to see the guilty party being brought to justice in the courts?

    How can behaviour which brings society to its knees get off scotch free, while 3 strikes for shop lifting gets you 10yrs?

  3. Peter Mizla says:

    The twisting and manipulation by the far right is reaching a fever pitch for climate change- the smearing, of scientists, organizations and the desperate attempt at grasping for anything to change the reality is stunning.

    that same far right is reaching a frenzy also in every economic and social debate as well.

  4. MarkB says:

    The word “alarmist” never flies past the radar of political hacks. Scientists need to be on guard with how they communicate publicly, unless they don’t care if their words are twisted.

  5. catman306 says:

    These guys aren’t alarmists. They are Stanford University climate scientists. And I think they are optimists, too.

    Heat Waves Could Be Commonplace in the US by 2039

  6. homunq says:

    I know that that’s a low-resolution scenario which is very loose on the details. But there are only 3 places in the world I can see where there is less than 3C rise over land: the southern caribbean (belize, costa rica, etc.); eastern Brazil; and southwestern Australia. All three of those are already a bit on the hot side for most people’s taste, though they’re pretty liveable.

    Buy your land now.

  7. homunq says:

    And what’s with the white pixel over western Iceland? Model broke down?

  8. More and more I see decentralized clean energy as a survival tool on a household and community level. While I hope organized efforts to change societal direction are successful in time, I wouldn’t count on it. The same forces financing deniers will keep at it until their last billions. I don’t see courts defying them in the short run. However, in daily life, excessive heat tends to make people irrational. So there’s likely to be panic and violent lashing out before there is correction let alone retribution through the courts.

    To keep cool in all senses, you may well need your own solar collectors etc. to run your air conditioning, as well as applying design and conservation to keep your spaces cool and minimize your energy needs.

  9. Robert says:

    When the last denier has finally given up in the face of overwhelming evidence, then what will happen?

    I have this uncomfortable feeling that the human race simply does not have the political / voting will power to do anything about it. Sure, we can build lots of wind farms and solar collectors and this will increase the net energy at our disposal. But the real problem is how do we stop using fossil fuel? How do we stop all countries and businesses from digging it up and burning it (other than by just running out, which is the default solution).

    This, for me, is the real problem. Exchanging insults with deniers is fun but it is all a bit of a distraction.

  10. Tim Maher says:

    Robert (#9 above me), two notes:
    1. Yes, bickering/distraction is exactly what the puppeteers want.
    2. Spending time defeating their lies is certainly a distraction from solving the problem but it is also part of the solution. This fight is out of the realm of science (the deniers are not using actual science) and into the realm of politics…

    Interesting, but places like CP are basically on the front-lines of this battle.

    That being said, the REAL way to solve this problem is to find a few billion dollars and hire the largest/best PR/Marketing firms to jam the truth down peoples throats from all possible angles for as long as it takes. I’m talking about the companies that found a way to sell an ipod to my 7 year old nephew…the companies that have a full staff of anthropologists/behavioral scientists/psychologists.

    Research in the social sciences have confirmed time and time again that people do not make decisions (change their mind) based on facts/information; people make decisions based on a host of other factors/variables, mainly to fit-in with their neighbors (social norms).

    I say again, we are now out of the realm of science and facts, what we need is for the scientists to hire social scientists.

    Joe, in the meantime, keep up the good work! Every day, your blog becomes more and more valuable to the global community!

  11. Robert says:

    Tim, I agree with what you say, but it doesn’t get away from the problem. Almost everyone knows that double quarter pounders are full of fat and cholesterol but they just keep eating them anyway because they taste nice. People would not choose to be morbidly obese but many just can’t help stuffing those burgers down their throats.

  12. fj2 says:

    Civilization is in the direct path of gathering storms driven by the dynamics of unstable equilibriums and amplifying feedback processes beyond any type of normal reconciliation.

    Many have had the vision to see them coming.

    An extreme few have the vision to see strategies for critical paths to action, mitigation, the potential for humanity’s survival, and even advancement to a very comfortable successful global civilization.

    To-date nothing has been done to effectively prepare as natural buffers to these storms — our most potent allies — vanish before our eyes.

    Civilization’s major buffers are also starting to erode.

    As most of humanity lives on the world’s coasts — in addition to inland areas in many cases even more vulnerable from lack of water — the main assaults could start soon, possibly even this year or next with major weather events devastating civilization’s great centers beyond the heat wave that killed 30,000 in Europe, the Katrina tropical cyclone, and the one in one-thousand year rain event in Nashville.

    Like after 9/11 some of the worse events will cause manmade emissions to temporarily drop precipitously and ultimately, low manmade emissions will not be so short-lived; a scenario that will be nothing to look forward to.

    Luck may extend the onslaught of assaults beyond the end of this decade and not much of a consolation.

    To repeat: Survival and advancement to a very comfortable successful global civilization is possible.

    Defeatism helps nothing.

  13. Dorothy says:

    I really agree with you, Tim Maher, on the need to “find a few billion dollars and hire the largest/best PR/Marketing firms to jam the truth down peoples throats from all possible angles for as long as it takes.”
    But I can’t see wasting valuable time on responding to stupid comments as part of the solution. The denier types will find a way to disagree with anything that doesn’t fit in their corporate think tank box. Here’s an example received July 7 at
    “Another study by Climate Analytics, at the Potsdam Institute in Germany, suggests there is “virtually no chance” world governments will keep the temperature rise to below 2C”
    Absolutly correct, of course there is no way world governments can do this because humans are not the cause. I truly love studies which support the skeptics. Wahoo!”

    I just hit the delete button.

    I like your site, Argonaut Planet, Tim, and will include it in our blog roll. And as always, huge thanks to you, Joe, for such a comprehensive post. Everything anyone needs to know is right here.

  14. Sue in NH says:

    The more I watch the drama of humans interacting with “mother Earth” in oblivious fashion, the more I am convinced that Earth is on a path to self-correct its climate, as it has done many times in geologic past.

    Unfortunately, I think the only way Mother Earth can accomplish this is to give a big enough hiccup that will cause a vast reduction in human population.. perhaps even extinction. If any humans remain, one must hope they will have learned their lesson, and will carry it forever… never again to make the same mistakes.

    I don’t believe in the Gaia hypothesis in any sort of magical-spiritual way. But I do see how the biosphere has consistently played a great part in adjusting GHG levels for the last 500 million years.

    Many species will alter their environment until it is no longer suitable habitat for them to live… that is what ecological succession is about. Looks like humans are creating a grand example of this on a global scale. The 6th great extinction, will be followed by a few tens of millions of years of explosive evolution. Will vertebrates still reign, or will it be arthropods, or another group?

    The average “life span” of a mammal is some where around a few million years. Maybe our turn is up soon. I could see that happening. Some days I hope that’s as bad as it gets. What I truly fear is Jim Hansen’s Venus scenario, and the death of the whole planet.

    Guess I’m having a bad day..

  15. Windsong says:

    When you see pictures like the ones in the Gulf, where large sea birds resemble crying, mud- models rather than real, animate creature, it makes you so depressed and sick, what does it matter if “our species’ time is up” as the poster above wrote? Maybe it should be.

  16. Windsong says:

    To Joe Maher, #10: there are “eco-barons”, extremely wealthy individuals who devote their billions of dollars to saving this planet… described in the book, “Eco-barons”. They could do the trick.

    Also, I was thinking of maybe a song… that way, the lyrics (facts on GW) could finally sink into peoples’ conscousness and rival the sound bites promulgated by the fossil fuel industry. I wrote a poem/song this past winter, called, “Precipitation”.

  17. James says:

    Over at Stoat, WC suggests not much evidence for the acceleration of carbon cycle feedbacks.