Science Stunner: Observations Support Predictions Of Extreme Warming And Worse Droughts This Century

“Future warming likely to be on high side of climate projections,” concluded a new analysis by scientists at the National Center for Atmospheric Research (NCAR). And that “higher temperature rise would produce greater impacts on society in terms of sea level rise, heat waves, droughts, and other threats.”

Many in the media have been getting this story wrong — unintentionally lowballing the future warming we should expect this century if the NCAR analysis is correct. For instance, the Washington Post writes, “the world could be in for a devastating increase of about eight degrees Fahrenheit by 2100, resulting in drastically higher seas, disappearing coastlines and more severe droughts, floods and other destructive weather.”

Not quite. The news release makes clear that amount of warming would likely occur well before 2100. Since this confusion is quite common in climate coverage, I’ll quote at length from NCAR to set the record straight:

The most common benchmark for comparing model projections is equilibrium climate sensitivity (ECS), or the amount of warming that eventually occurs in a model when carbon dioxide is doubled over preindustrial values. At current rates of global emission, that doubling will occur well before 2100.

For more than 30 years, ECS in the leading models has averaged around 5 degrees Fahrenheit (3 degrees Celsius).  This provides the best estimate of global temperature increase expected by the late 21st century compared to late 19th century values, assuming that society continues to emit significant amounts of carbon dioxide. However, the ECS within individual models is as low as 3 degrees F and as high as 8 degrees F.

At current rates of global emissions, that doubling (to 550 ppm) will occur around mid-century, and we might approach a quadrupling by 2100!

The “good news” is that inherent delays in the climate system mean we don’t hit the ECS immediately upon doubling. The “bad news” is that the ECS ignores key non-equilibrium feedbacks like the release of carbon currently locked in the frozen tundra (see “Carbon Feedback From Thawing Permafrost Will Likely Add 0.4°F – 1.5°F To Total Global Warming By 2100“).

The NCAR release continues:

“There is a striking relationship between how well climate models simulate relative humidity in key areas and how much warming they show in response to increasing carbon dioxide,” Fasullo says. “Given how fundamental these processes are to clouds and the overall global climate, our findings indicate that warming is likely to be on the high side of current projections.”

… Estimates based on observations show that the relative humidity in the dry zones averages between about 15 and 25 percent, whereas many of the models depicted humidities of 30 percent or higher for the same period. The models that better capture the actual dryness were among those with the highest ECS, projecting a global temperature rise for doubled carbon dioxide of more than 7 degrees F. The three models with the lowest ECS were also the least accurate in depicting relative humidity in these zones.

So the study didn’t find, as the Post and other media outlets assert, that “the world could be in for a devastating increase of about eight degrees Fahrenheit by 2100.” The study  found the “global temperature rise for doubled carbon dioxide of more than 7 degrees F.”

The temperature rise we would see in 2100 would depend on how much beyond (or below) 550 ppm we are at that time plus  the impact of the various feedbacks not incorporated into the ECS. If we hit 1000 ppm, warming would likely exceed 11 degrees F — possibly by a few degrees!

Of course, the first 7 F  would devastate civilization, but, even so, 14 F would still be unimaginably worse — rendering large parts of the planet’s currently habited and arable land uninhabitable, superheated dustbowls and rendering large parts of the ocean, superheated, acidic dead zones.

Here is a figure from the release that helps to explain how the NCAR scientists — John Fasullo and Kevin Trenberth — used real-world observations to come to their conclusion:

Computer models that more accurately depict dry conditions in a key part of the subtropical atmosphere are also more likely to predict greater climate warming from increased greenhouse gases. In this graphic, each star indicates one of 16 leading global climate models. The left axis (“warming”) corresponds to equilibrium climate sensitivity (ECS) in degrees C, which is the amount of warming produced by each model when carbon dioxide concentrations in the atmosphere are doubled over preindustrial values. The bottom axis shows May-to-August relative humidity for a portion of the upper atmosphere between about 20,000 to 30,000 feet in height and between about 10° and 25° latitude south in the southern subtropics. (©UCAR. Image by Carlye Calvin, based on Fasullo and Trenberth, Science, 2012.)

Finally, NCAR notes that the findings ” could provide a breakthrough in the longstanding quest to narrow the range of global warming expected in coming decades and beyond.”  Climate Central notes:

“It’s a very clever idea,” said Andrew Dessler, a climate scientist at Texas A&M University who studies clouds, among other things. “And it may well be right. They’re sensible people, and I have a lot of respect for them. But more work is needed to flesh out the details.”In a commentary also appearing in Science, Karen Shell of Oregon State University wrote that Trenberth and Fasullo’s approach “is an encouraging step that links observations to climate sensitivity” — that is, to the amount of heating a doubling of CO2 will cause.

But the case isn’t ironclad: relative humidity is clearly related to cloud formation, she noted, but there could be plenty of other factors that are nearly as important.

“In retrospect, this could turn out to have been a breakthrough,” Dressler said. “But we won’t know that for a while.”

The full study can be found here (subs. req’d).

50 Responses to Science Stunner: Observations Support Predictions Of Extreme Warming And Worse Droughts This Century

  1. idunno says:

    …and also…

    Climate scientists show a systematic bias towards cautious estimates, away from alarmism.

  2. Peter Whitehead says:

    this is looking like a mass extinction event – as top predators we don’t look good as survivors.

    a typical mass ext event takes out over 90% of species..

  3. Aleph Null says:

    If Fasullo and Trenberth’s result that an ECS of 4.5°C is correct, that puts the atmospheric CO2 trend on the rising, dark blue line of this diagram from MacDougall et al.

  4. prokaryotes says:

    It seems this study does not incorporate the Methane feedback from thawing permafrost.

  5. prokaryotes says:

    Nvm, the article states it:

    “The “bad news” is that the ECS ignores key non-equilibrium feedbacks like the release of carbon currently locked in the frozen tundra (see “Carbon Feedback From Thawing Permafrost Will Likely Add 0.4°F – 1.5°F To Total Global Warming By 2100“).”

  6. Merrelyn Emery says:

    Thank goodness they are finally using observational data instead of selected linear projections. It’s probably too late to radically change our chances but an understanding of the Earth as a system may aid the 10% with their hunting and gathering, ME

  7. Jack Burton says:

    “Feed Backs” get ignored because they can’t be predicted with any certainty. But their potential is well known and plenty of evidence is coming in that feed backs are underway.
    Just the simple arctic ice melt and the feed back associated with more heat being absorbed by the newly open dark waters may have put the arctic ice into a death spiral. A melting arctic opens up a whole lot of extreme weather prospects. Maybe even the recent storm in the NE USA could be directly related to the melted ice of this very year.
    CO2 increases at a very alarming rate as other nations advance into USA levels of energy usage. It is a bleak prospect, my simple guess is that the warming is 50 years ahead of what was expected by recent scientific models. Nobody came close to predicting the level and speed of arctic ice melt. This is a warning, a dire warning!

  8. Paul Magnus says:

    Oh dear… not good!

    Climate Portals shared a link via Climate Chaos on FB 2 minutes ago

    Climate change ‘likely to be more severe than some models predict’
    Scientists analysing climate models warn we should expect high temperature rises – meaning more extreme weather, sooner

    Given this year’s extreme weather, the results of the NCAR may not surprise some.

    And Arctic melt….

  9. Paul Magnus says:

    Its not going to be pretty.

  10. Paul Magnus says:

    Some one up there should have the guts to declare a global/national emergency and start to implement ww2 measures … like rationing etc.

    Who are we trying to kid?

  11. EmuBob says:

    It’s not the fiscal cliff that needs the government’s urgent attention, it’s the climate cliff.

  12. Paul Magnus says:

    The rhetoric across the board, should certainly be approaching this level of concern…

  13. Mike Roddy says:


    The best thing Obama could do would be to fire Chu and make you the new Energy Secretary. The deniers will go nuts, but that’s a good thing. We are in a battle, and it’s about time everybody admitted it. At least we won’t have the spectacle of Chu, Salazar etc tying themselves in knots.

    If Bush can recruit his energy team straight from the oil companies, whey can’t Obama pick an actual scientist, who is not afraid to do what needs to be done?

    Your challenge wouldn’t be Congress as much as Salazar and Vilsack who, like Chu, will be uselessly throwing bones to both sides. You have shown great leadership here on Climate Progress and in your public appearances and writings. It’s about time the rest of the country got acquainted with this monumental issue, in language where the facts govern.

  14. Chris G says:

    Our species is omnivorous and generally very good at exploiting whatever energy/food sources there are. We may be the most successful invasive species that has ever been. So, barring an anoxic ocean event or similar, our species will likely survive. ‘Course, that does not mean that the times will not be “interesting”.

  15. prokaryotes says:

    Yes, and our collective actions, our flawed swarm intelligence is sheep and shy of change.

    It looks bad but not lost yet. The next 4 years are crucial. I hope that somebody makes this very clear to the GOP and any attempts of watering down climate actions, which are directly tied to today’s and future National Security, on a global scale.

  16. prokaryotes says:

    This Toles cartoon pretty much sums it up for me

    Humans are liek a frog sitting in soon to be boiled water… “but wait it is just a bit warmer” aaaand then we turn up the crazy… Heating

  17. niall says:

    Ehh, no, only the worst mass extinction event ever (End-Permian) appears to have resulted in a loss of around 90% of known species … higher for marine species, lower for land vertebrates. c.75% overall for the K-T event (most recent ‘large’ one).

    A mass extinction event is any instance of the rate of extinctions rising significantly above the background rate. ‘Significance’ is debatable, but the lower you count it, the lower the ‘typical’ value would be.

  18. prokaryotes says:

    It would be great if CP and others start assessing in more detail the steps which have become a necessity to prevent a climate which is predicted.

    The Co2 equivalent from the carbon emitted from replacing and cleaning up Sandy’s aftermath alone, might shrink current Co2 reduction affords – irrelevant.

    We need to stop burning fossil fuels, this includes Co2 free city center, where only cars with new clean engines can go. More mass transit, energy efficiency, quality-longevity standards for every day products and renewables. But how much how fast?

  19. PeterM says:

    There has been some revival in Washington political circles of a carbon tax again being brought forward to help reduce the deficit and begin to address GHG emissions.

    That climate sensitivity to GHG is worse then we expected, compared to a decade ago is now becoming an unwelcome revelation. The warming already taken place, 0.8 degrees C above the PI level, and at least that much in the ‘pipeline’ says that our time is up to prevent an increasingly hostile climate going forward. Avoiding 2 degrees is now unlikely- and that is too much anyway.

  20. fj says:

    It has to be hammered into the public mind that climate change is accelerating and the type of action required will have to be characteristic of what Bloomberg and Obama have done responding to Hurricane Sandy and still a work in progress . . . but much more.

  21. fj says:

    Rapid development of net zero mobility solutions, smart micro grids, rapid deployment of high efficiency improvements and solar are likely critical paths toward developing these action plans.

    Facilitating and encouraging rapid social changes such as poor-people-first, universal healthcare, greatly improved education systems and accessibility to advanced learning environments, and not blue-collar-only unions greatly reducing income and wealth disparities are others.

  22. John McCormick says:

    Chris, you aren’t thinking.
    “our species will likely survive.”

    Maybe you re new to the science.

    Nothing will stop temperature rise at 2 degrees C. It keeps moving up the thermometer. At some point our species will succumb to heat greater than our bodies are able to accommodate. Yes, we expire.

  23. BillD says:

    As a scientist, I take it for granted that when scientists give an estimate, there is a 50% chance that it’s too high and a 50% chance that it’s too low. Scientists really are not like polticians, advertisers and salesmen who inflate their positions. I hope that people learned from Nate Silver’s blog, where Nate published his rational, objective, nonpartisan methodology before the election and then just followed it. While it’s true that journalists often hype scientific results, this is not what scientists do. We do sometimes point out–“well, if the reality equals or exceeds our median predictions, things could get really bad.”

    Why is it that so few people seem to think about estimates and projections as “probability distributions,” something that is the basis of just about all science-based policy? After serving as an author, editor or reviewer of over 1,000 peer reviewed science manuscripts, I can say that scientific authors who overstate conclusions based on their data are universally rejected or required to be more cautious. But somehow much of the public associates cautious, reasoned, probabilistic statements as an indication of weak results.

  24. Dennis Tomlinson says:

    As an engineer and part-time teacher of math, I’d proffer the questions: 1) What is the mean? 2) What is the Mode?, and 3) What is Standard Deviation? asked in one of those “man-on-the-street” interviews would yield the answers such as, in order: A) A kick-ass foreign policy. B) A place where you can relieve yourself., and C) Do you mean pervert?
    Ambassadors of Science like Sagan and Tyson are rare. I can’t think of solutions that doesn’t involve advocates and persuasive interpreters – an endeavor at which I, personally, have failed. And to date, politicos like Markey, Whitehouse, Wyden, and Kerry have failed as well. Where is Superman when we need him? Dare we hope?

  25. Wes says:

    Wow! When I saw a couple of references to possible mass extinction 12 – 18 month ago it was just a worst-case projection on a couple of small science blogs. How times change. Now it’s looking high probability. How do we get the attention of someone who matters? Or someone who cares about their grandchildren? Is Bill McKibben talking it up on his tour?

  26. MarkF says:

    Very good idea, how does it get from here to Obama?

  27. I think I may have the first hand scoop on that one. I was at the 350 tour event on Portland on Nov. 8th. Bill received a text DURING the show from Kevin Trenberth in reference to a study that just released particularly alarming news. I’m guessing it was this study.

  28. Dr.A.Jagadeesh says:

    Yes. The Effects of Global Warming are already seen in some regions.

    Dr.A.Jagadeesh Nellore(AP),India

  29. “Just the simple arctic ice melt and the feed back associated with more heat being absorbed by the newly open dark waters may have put the arctic ice into a death spiral.”

    It’s worst than that. Wadham’s team calculated that the mechanical heat gain for warming of the arctic oceans alone equals about 24 years worth of human CO2 emissions.

  30. Chu is an actual scientist, he’s got a Nobel prize. But now he’s a bureaucrat — head of the Lawrence Berkeley Labs — meaning a grant getter. Like the rest of the Obama administration, he’s committed to the political doable, not what needs doing.

  31. “Why is it that so few people seem to think about estimates and projections as “probability distributions,” something that is the basis of just about all science-based policy?”

    Maybe it’s got something to do with droughts, hurricanes and tornados, which don’t feel particularly “probabalistic” when they land on your head.

  32. prokaryotes says:


    The amplifying feedback mechanism of polar ice melt is the so-called albedo-flip effect, where loss of reflection by melted ice is compounded by infrared absorption by open water, a process currently taking place in the Arctic Sea, as reported by Hansen et al.: “… amplifying feedbacks make ice sheet disintegration necessarily highly non-linear. In a non-linear problem, the most relevant number for projecting sea level rise is the doubling time for the rate of mass loss. Hansen (2007) suggested that a 10-year doubling time was plausible, pointing out that such a doubling time from a base of 1 mm per year ice sheet contribution to sea level in the decade 2005-2015 would lead to a cumulative 5 m sea level rise by 2095.”

    “Just the melting of all the floating ice in the arctic ocean, will add as much heat to the earth, as all the Co-2 we put in the atmosphere to date.” Prof. James Lovelock

    Estimating the Global Radiative Impact of the Sea-Ice-Albedo Feedback in the Arctic a more realistic ice-free-summer scenario (no ice for one month, decreased ice at all other times of the year) results in a forcing of about 0.3 W m−2, similar to present-day anthropogenic forcing caused by halocarbons. BBC Interview with James Lovelock

  33. Mulga Mumblebrain says:

    fj, all of your excellent recommendations, which I agree with 110%, are viscerally opposed by the Right. Indeed it is the Right’s mission in life to impose exactly opposite outcomes in all those fields, and I can only recall a few Rightists (like our excellent former PM, Malcolm Fraser, once, in my opinion, a swine, now very much a moral exemplar)who ever admitted error, learned from their mistakes or evidenced any human sympathy for the suffering of others.

  34. Mulga Mumblebrain says:

    ‘The Mean’ are the Right, as in their religious belief that ‘The mean shall inherit the Earth’.

  35. Mulga Mumblebrain says:

    Surely people have been comparing our situation to previous mass extinctions for decades. Richard Leakey and Roger Lewing published ‘The Sixth Extinction’ in 1995, and I’m sure I saw ‘alarmists’ raising the possibility long before that. In fact I remember Edward Goldsmith in the late ’80s predicting human extinction if another forty years of environmental destruction like that which had occurred since WW2, went on in the same fashion.

  36. Merrelyn Emery says:

    Put away the top down methods. Get people together as equals to share their perceptions of what has been going on, look at the implications and work out what they are going to do about them. You will find they will come up great ideas, a huge majority of which are unanimous, and will go out to implement them. Superman is not required, ME

  37. Mike Roddy says:

    I’ll be attending his event Sunday in Los Angeles. If I get a chance to talk to McKibben I will report the outcome here.

  38. Dennis Tomlinson says:

    You are, on average, quite correct.

  39. Mulga Mumblebrain says:

    It’s the rocks at the base of the cliff that excite my dread.

  40. Billy52 says:

    If we get anywhere near 8 degrees F. warming by 2100, the impact will be devastating. This is a global emergency and we’d better get our act together soon or it’ll be too late, if it isn’t already too late.

  41. Chris Mclean says:

    Agree with fj ^ This is the place to start. And yes Mulga is correct that “conservative” national political parties oppose this. The connection you may not see is that Rightist political groups believe in self government/state rights. This mindset is found with those who affiliate with fear of an oppressive government. They are sensitive to measures like this and require tremendous patience & understanding & mediation BEFORE you attempt to issue measures in the political arena.

  42. Chris Mclean says:

    It is too late. Period. However, we have work to do.

    No one can go back and start a new beginning, but anyone can start today to make a new ending.

    Thus, the depth of the suffering is in our hands just like it already was…its the same with self consciousness IMO.

  43. Dan B says:


    Note to NCAR:

    Say this, “By rapidly converting to clean energy we stand a chance that humanity will survive. It’s the practical, scientific, and moral choice for us and for our children. Americans have risen to challenges like this before. We dragged our feet in World War II. We fought for freedom now we must join the fight yet again. That’s the choice.”

    If you don’t say this your words will be heard as the words of wimps. Spineless equivocating wimps, even if you believe your words are blunt and courageous. They’re not yet.

  44. Merrelyn Emery says:

    Quite right Philip. Most people, including scientists in their unacknowledged moments, trust, and base their decisions on, ecological knowledge derived from perceptions and experience, not abstractions. That’s why the deniers have their backs to the wall, ME

  45. Thanks, Pro. More useful but discouraging information.

  46. Unacknowledged or unguarded moments. Past is prologue, and us common folk look at what’s going on around us to plan for the future. It might not be good science, but it is an evolutionary skill that got us through the first million years. Who knows, it could get us past this too, if we start paying attention to our instincts. Instead of all the endless debate about the attribution of this or that exteme weather event to global warming, we can just say, IT’S GLOBAL WARMING, STUPID — and get on with fixing it.

  47. prokaryotes says:

    We play a game, when parts of the ballpark become uninhabitable regions…

    A 2009 paper by Sherwood and Huber examines a worst case scenario in which the average global surface temperature warms in the ballpark of 10°C a few centuries in the future. They note that a wet-bulb temperature (Tw) exceedence of 35°C for extended periods should induce hyperthermia in humans and other mammals, as they become unable to sufficiently dissipate heat. In short, if Tw(max) of a particular region were to exceed 35°C for long periods of time, that region would effectively become uninhabitable to mammals.

  48. BillD says:

    The idea of mass extinction as a result of current and projected climate change is not new. Deforestation has already caused much extinction. An academic edited book, reviewed in the most recent issue of Ecology has 1 million extinctions in its title. I thought that this was extreme for an academic book, but maybe not.

  49. Not. There have been way more than 1 million extinctions already. We haven’t catalogued most of them, because they involve tiny creatures that go extinct when their habitats are disrupted. But the fact that we are unaware of their fate does not means it has any less impact on the planet. Microorganisms underly the entire biosphere’s viability, and the more they are disturbed, the less resilience the system has.

  50. perceptiventity says:

    ‘We are now well into a global crisis that may mark the end of this cycle of human civilization. In this note I present a summary of what’s going on as far as I can tell, as well as a scenario for how things might develop over the next 75 years or so.’