Tumblr Icon RSS Icon

Media Misleads On Flawed Climate Sensitivity Study: Avoiding “Drastic Changes Over Land” Requires Emissions Cuts ASAP

By Joe Romm  

"Media Misleads On Flawed Climate Sensitivity Study: Avoiding “Drastic Changes Over Land” Requires Emissions Cuts ASAP"

Share:

google plus icon

http://cdn.greenoptions.com/e/e1/1000x500px-e12af180_sensitivity-big.gif

A new, deeply flawed study on the climate’s sensitivity to greenhouse gas emissions reveals just how poorly the media understand key climate science issues.  It also reveals how eager some in the media are to push the mistaken message that failure to act quickly and aggressively on GHG emissions would not be catastrophic.

Here’s what you need to know about the study by Schmittner et al in Science (subs. req’d):

  1. Its key finding is that the so-called “fast-feedbacks sensitivity” of the climate (to a doubling of CO2 levels) is on the low side.  This finding is likely wrong, according to many leading climatologists (see below).
  2. Even if the study’s findings hold up, we are headed toward high warming on our current GHG emissions path.  That’s because we are headed toward a tripling or higher of CO2 levels and because the slower feedbacks ain’t so slow (see “NSIDC bombshell: Thawing permafrost feedback will turn Arctic from carbon sink to source in the 2020s, releasing 100 billion tons of carbon by 2100“).
  3. The study finds that small changes in Earth’s temperature can have huge impacts on the land — that’s why it finds a low sensitivity!

This last, crucial point seems to have escaped the attention of many U.S. reporters on the study — even though it is quite clearly stated in the study’s news release:

“It shows that even very small changes in the ocean’s surface temperature can have an enormous impact elsewhere, particularly over land areas at mid- to high-latitudes,” [Schmittner] added.

Note to media:  Most Americans live on “land areas at mid- to high-latitudes.”

“Hence, drastic changes over land can be expected,” he said. “However, our study implies that we still have time to prevent that from happening, if we make a concerted effort to change course soon.”

In short, act quickly and aggressively or suffer drastic impacts.

Now contrast that to Eric Berger, science reporter for the Houston Chronicle, who writes in his mis-summary of the paper:

To me, the real effect of this paper will be to really impair the credibility of the more extreme environmentalists who have been saying the planet faces certain doom from climate change.

I am thinking about such efforts as Bill McKibben’s 350 campaign….  Such environmentalists assert that the planet will warm as much as 6 Celsius degrees with a doubling of atmospheric carbon dioxide levels.

That’s a big number and doubtless would have catastrophic consequences for the planet. This is not in dispute. But scientists are now telling us this is not going to happen.

Actually, it is Berger’s credibility that has taken a hit, and he owes McKibben an apology.  For the record, McKibben doesn’t say we are facing “certain doom” from climate change.  He — and NASA’s James Hansen, the scientist  whose work inspired McKibben — typically say we are headed for multiple catastrophes if we stay anywhere near our current emissions path.

This new study does not contradict that view.  Indeed, it supports it. As Skeptical Science (SkS) concluded its summary:

In fact if Schmittner et al. are totally correct, we may be in for some rapid climate changes in the relatively near future.

Moreover, many major, independent studies suggest that, yes, we are risking 6°C (11°F) warming on our current emissions path (see Hadley Center: “Catastrophic” 5-7°C warming by 2100 on current emissions path and M.I.T. doubles its 2095 warming projection to 10°F — with 866 ppm and Arctic warming of 20°F.

And don’t forget those darn extreme environmentalists at the International Energy Agency this month — see IEA’s Bombshell Warning: We’re Headed Toward 11°F Global Warming and “Delaying Action Is a False Economy”.

Berger actually cites Hansen’s main finding but then trashes it because he doesn’t appear to understand what Hansen (and many others) have found.  As Skeptical Science explained (see this post):

A 2008 study led by James Hansen found that climate sensitivity to “fast feedback processes” is 3°C, but when accounting for longer-term feedbacks (such as ice sheet disintegration, vegetation migration, and greenhouse gas release from soils, tundra or ocean), if atmospheric CO2 remains at the doubled level, the sensitivity increases to 6°C based on paleoclimatic (historical climate) data.

The fact is we’re already seeing the acceleration of the “slower” amplifying feedbacks (see Stunning Peatlands Amplifying Feedback: Drying Wetlands and Intensifying Wildfires Boost Carbon Release Ninefold).

To be crystal clear, since it isn’t just Berger but also the New York Times and others who seem confused about this, the amount of warming we are going to subject our children  and countless future generations to depends primarily on three factors:

  1. The sensitivity of the climate to fast feedbacks like sea ice and water vapor (how much warming you get if we only double CO2 emissions to 560 ppm and there are no major “slow” feedbacks).  We know the fast feedbacks are strong by themselves (see Study: Water-vapor feedback is “strong and positive,” so we face “warming of several degrees Celsius”).  Indeed, the results of a major recent Journal of Climate study on cloud feedback  “provide support for the high end of current estimates of global climate sensitivity.”
  2. The real-world slower (decadal) feedbacks, such as tundra melt and peatlands and drought-driven emissions (see Science: Second ’100-year’ Amazon drought in 5 years caused huge CO2 emissions. If this pattern continues, the forest would become a warming source).
  3. The actual CO2 concentration level we are likely to hit, which is far beyond 550 ppm (see Biggest Jump Ever in Global Warming Pollution in 2010).

Indeed, it was the IPCC itself that warned we are headed toward 1000 ppm, particularly if the decadal carbon-cycle feedbacks do kick in — see “Hidden Bombshell in the IPCC Fourth Assessment” and my discussion in Nature online.

Schmittner et al only deals with #1. Sadly, #2 and #3 are more than enough to ensure humanity’s destruction even if Schmittner et al is right, indeed, especially if it is right.  But it probably isn’t.

Why Schmittner et al is likely wrong about the fast-feedbacks sensitivity

CLICK HERE TO READ MORE OR COMMENT


There are a few big flaws in the paper.  First, a potentially big issue:

Dr. Schmittner acknowledged another potential problem: that his computer analysis did not take good account of potential changes in clouds. Because clouds affect sunlight absorbed at the Earth’s surface, excluding them means “the range that we estimate for climate sensitivity may be too narrow,” he said.

Well, if the range is too narrow, that means the whole paper may be consistent with a high sensitivity — a point climatologist Richard Alley makes in detail below.  And that would mean the entire paper is much ado about nothing.

Consider the November 2010 news release from the Journal of Climate study on potential changes in clouds:

Co-author Kevin Hamilton concludes, “If our model results prove to be representative of the real global climate, then climate is actually more sensitive to perturbations by greenhouse gases than current global models predict, and even the highest warming predictions would underestimate the real change we could see.

D’oh!

But the key reason Schmittner et al is probably wrong is the same reason it is still worrisome if it is true — the entire analysis is based on a low-ball estimate of the warming since the Last Glacial Maximum (LGM) approximately 20,000 years ago:

“combining extensive sea and land surface temperature reconstructions from the Last Glacial Maximum with climate model simulations we estimate a lower median (2.3 K) and reduced uncertainty (1.7–2.6 K 66% probability).”

As SkS notes, “This estimate is significantly narrower and a bit lower than the IPCC-estimated 66% probability range for equilibrium climate sensitivity of 2 to 4.5°C for doubled atmospheric CO2.”  Skeptical Science explains the issue:

There are some unusual aspects about this study which require further investigation before the conclusions of the study can be accepted, as the authors themselves point out.  For example, the study uses a relatively new global mean surface temperature reconstruction for the LGM of just 2.2°C cooler than interglacial temperatures in the locations where they have proxy data, or 2.6°C when averaging globally.  This is significantly lower than most paleoclimate estimates, which generally put the LGM in the range of 4 to 7°C cooler than current temperatures.  For comparison, in their study also using the LGM to constrain climate sensitivity, Hansen and Sato (2011) used a mean surface temperature change of 5°C, consistent with the body of literature (Figure 2).

Fig 2

Figure: Climate forcings during the ice age 20 ky ago relative to the pre-industrial Holocene from Hansen and Sato (2011)

Since the radiative forcing associated with doubled CO2 is 3.7 Watts per square meter (W/m2), Hansen and Sato’s result implies a fast-feedback climate sensitivity of 2.8°C, which is slightly outside the Schmittner et al. 66% probability range (at the upper end of their 90% probability range).  In fact, as Urban explains, the main reason Schmittner et al. arrive at a lower climate sensitivity estimate than previous studies is due to their lower LGM temperature reconstruction:

“our LGM temperature reconstruction is quite different from what has been commonly assumed, and our study may prove inconsistent with other evidence that we have not yet considered. This is something that will have to be sorted out by further debate and research … our new temperature reconstruction explains a lot of the difference between our climate sensitivity estimate and previous estimates.”

In an interview with New Scientist on this paper, Gavin Schmidt said:

The model estimate of the cooling during the Last Glacial Maximum is a clear underestimate….  A different model would give a cooler Last Glacial Maximum, and thus a larger sensitivity.”

Climatologist Richard Alley made the same point in great detail in an email.  As the NY Times cited him:

Richard Alley, a geoscientist at Pennsylvania State University, said some scientists have questioned the data set’s accuracy and prefer using other ocean temperature estimates than the ones the researchers employed. This points to a flaw in the data set rather than the research design, he said in an email, and he thinks the authors might have found similar results to previous work if they had used a more “fully consistent and accurate” database.

I would not conclude from this study that the estimates of future global warming are overblown,” Dr. Alley said. Given the vast array of data from other studies, Dr. Alley thinks that it is “much too early to assume that the climate sensitivity is low.”

The new study uses “global sea surface temperatures (SSTs) from the Multiproxy Approach for the Reconstruction of the Glacial Ocean (MARGO) project.”  In his email to me, Alley explained that our understanding of sensitivity is pretty solid:

Very many estimates are included in our understanding that the climate sensitivity is near 3 C, with some chance of a value a little higher or lower, and very slight chance of a value much different from 3 C but with somewhat more chance on the high end than the low end.

He directs people who want to understand the issue to one of the most comprehensive review articles on the subject, Knutti and Hegerl.  Alley points out that

Notice, however, in Figure 4 in the new paper, that the most-likely answer based on the land data is very different from the answer based on the ocean data (the global combined result is almost identical to the ocean result, not surprising given that the world is mostly ocean).  Furthermore, the land result is fairly consistent with the results in the Knutti and Hegerl paper from many different techniques and times and groups and models, whereas the ocean result looks rather different.

Alley believes “there is a reasonably high probability that either the land data, or the ocean data, or both, are in error.” As he explains, it’s probably the ocean data:

MARGO made a solid effort, which indicates very small temperature changes. But, there are other ways to do it, and indeed, coauthor Alan Mix has published independent papers indicating that the temperature changes were larger in some regions than indicated by MARGO.   David Lea and others have also obtained larger temperature shifts….

In short, the MARGO data for the ocean show very small temperature change from the ice age to today, and thus lead to the low climate sensitivity, but they disagree with some independent estimates showing larger temperature change.  They also lead to disagreement with the pollen-based land temperature data.  Furthermore, they lead to an answer that disagrees with many other lines of evidence for climate sensitivity.

It remains possible that the new MARGO-based ocean-based estimate is correct, but with so many disagreements with other data, other studies of the last glacial maximum, and other studies of climate sensitivity not using the last glacial maximum, it is in my opinion much too early to assume that the climate sensitivity is low.  It would be much less surprising to me to learn that the MARGO data have underestimated the warming from the ice age, that the pollen data for the land are more reliable, and that the climate sensitivity from this new study, if done with a fully consistent and accurate database, would agree closely with the many other lines of evidence.  Indeed, given the comparison between MARGO and other ocean temperature data sets, including work by Alan Mix, indicating that the temperature changes were larger than reconstructed by MARGO and thus that the climate sensitivity is higher than in the ocean-only and combined ocean-land shown here, I believe that this paper is consistent with the great mass of other data indicating a sensitivity near 3 C.

That conclusions seems pretty solid.

A number of other climate scientists interviewed for a BBC article also expressed reservations about the study’s assumptions and results.  For example, the climate sensitivity in transitioning from a cold to warm period may be different than that in transitioning from a warm to a hot period, as Andrey Ganopolski noted:

There is evidence the relationship between CO2 and surface temperatures is likely to be different [during] very cold periods than warmer.”

… “One should be very careful about using cold climates to [construct] the future,” he added.

This is particularly true since the LGM only experienced fast feedbacks, whereas due to the rapid rate of the current climate change, slower feedbacks may be triggered on century timescales.

This is a key point.  Indeed, Alley makes this point in his email:

There is one other point possibly worth making.  The authors set the ice sheets and other features of the ice age to their full ice-age values.  The extended ice, lowered sea level, raised dust, and other features of the ice age, including features of the orbit, cause cooling that is not attributed to CO2 or other greenhouse gases.  But, we have fairly high confidence that the cooling from the drop in CO2 contributed to the ice growth and other changes leading up to the full ice age.  Thus, by initially specifying the full ice-age conditions, some of the cooling effect of the CO2 is omitted, lowering the climate sensitivity.  I believe that most commonly you will find the full effect of the CO2 discussed as a long-term climate sensitivity, as opposed to the short-term one calculated as these authors have done.  What these authors did is NOT wrong, and indeed is consistent with most of the literature in the field, but some authors have argued that it underestimates the climate sensitivity.

Precisely.

The key point is that if Schmittner et al were right, the climate is incredibly sensitive to small changes.  As SkS notes, “Schmittner et al. have assumed that the difference between a glacial maximum and interglacial temperature is a mere 2.6°C.  The global average surface temperature has already warmed 0.8°C over the past century.  During the LGM, the surface was covered with huge ice sheets, plant life was different, and sea levels were 120 meters lower.”  Schmittner himself notes the key conclusion:

Very small changes in temperature cause huge changes in certain regions, so even if we get a smaller temperature rise than we expected, the knock-on effects would still be severe.”

But remember, we’re headed toward a tripling or more of CO2 levels (from preindustrial values).  And the decadal feedbacks are already starting to kick.  Thus as Skeptical Science puts it:

If Schmittner et al. are correct and such a small temperature change can cause such a drastic climate change, then we may be in for a rude awakening in the very near future, because their smaller glacial-interglacial difference would imply a quicker climate response a global temperature change….  although the Schmittner et al. best estimate for climate sensitivity results in approximately 20% less warming than the IPCC best estimate, we also achieve their estimated temperature change between glacial and interglacial periods (the dashed lines) much sooner….

If Schmittner et al. are totally correct, we may be in for some rapid climate changes in the relatively near future, as we approach the amount of warming that separates a glacial from an interglacial period.

The bottom line is that this new study will very likely not result in any major revisions of the climate sensitivity range of the IPCC, and, if it were true, it is cause to be more concerned about our current do-nothing approach to emissions.

This post has been updated (because of an error in the Skeptical Science post).

Related Posts:

‹ Is This North America’s Greenest Building?

November 28 News: “Nowhere Else in the World Do You See a Political Debate About Whether Climate Science Is Real” ›

33 Responses to Media Misleads On Flawed Climate Sensitivity Study: Avoiding “Drastic Changes Over Land” Requires Emissions Cuts ASAP

  1. prokaryotes says:

    QUOTE

    “Very small changes in temperature cause huge changes in certain regions, so even if we get a smaller temperature rise than we expected, the knock-on effects would still be severe.”

    —-
    Snow melt, ice free conditions are causing more moist air, hence more precipitation. Because the winter month are warming more then others, we are likely to see repeat of last years season.

    We are already in exceptional (irreversible), climate situations, we need to act urgently to avert more rapid dangerous developments, which threaten civilization.

    Example what we looking at…

    Melting Arctic Sea Ice Causing Cold, Snowy Winters

    While it may be tempting to conclude the biting cold and endless snow characterizing this winter in the Northern US and Europe is just a random weather event, scientists say it’s a result of very rapid climate change.

    The warming and melting of the Arctic is happening much faster than expected. Some experts expect the summer Arctic ice cover to be essentially gone in as little as five years. Just a few years ago, no one thought a summer ice-free Arctic could happen before 2060.

    Arctic temperatures have been 21 degrees C above normal for over a month. New data reveals that huge volumes of warmer water from the North Atlantic are flowing into and warming the Arctic Ocean, researchers reported in the journal Science.

    “Boats were still in the water during the first week of January,” said David Phillips, a senior climatologist with Environment Canada, referring to southern Baffin Island, some 2,000 km north of Montreal. This is a region that receives just four or five hours of weak sunlight during the long winter. Temperatures normally range from -25 to -35 degrees C but were above zero on some days in January.

    An international team of researchers analysed marine sediments and found that temperatures of the northward inflowing Atlantic water varied by just a few tenths of a degree Celsius during the past 2,000 years. However, in the last hundred years temperatures have shot up by two degrees C.

    The Arctic and Antarctic regions are key drivers of Earth’s climate. The snow and cold in the eastern US and Europe during last year’s winter is being repeated this year – likely the result of the loss of Arctic sea ice.

    Over 90% of excess heat trapped in the atmosphere from burning fossil fuels is going into the oceans.

    As more and more sea ice melts, there is more open water to absorb the summer sun’s heat. A day of 24-hour summer sun in the Arctic puts more heat on the surface of the ocean than a day in the tropics, James Overland of the NOAA/Pacific Marine Environmental Laboratory in the United States told Inter Press Service .

    That extra heat in the ocean is gradually released into the lower atmosphere from October to January as the region slowly re-freezes months later than normal. This is a fundamental change – a large part of the Arctic Ocean is radiating heat instead of being cold and ice-covered. That has disrupted wind circulation patterns in the northern hemisphere, reported Overland and other researchers at the International Polar Year Oslo Science Conference in Norway last June.

    The result: the Arctic stays warm and mid-latitude regions become colder and receive more snow for much of the winter. Last December was the coldest south Florida has experienced in more than a century of record-keeping.

    Most of Britain suffered through its coldest December ever. Up in the Arctic, Coral Harbour on the northwest corner of Hudson Bay was above zero degrees C for two days in early January for the first time in history. Much of the eastern Arctic centred around Baffin Island averaged +21C above normal between Dec. 17 and Jan. 15 this year.

    This looks to be the new normal since Arctic experts agree the melting sea ice is now locked into a death spiral.

    “In future, cold and snowy winters will be the rule rather than the exception” in the eastern United States and Europe, Overland previously told IPS.

    This week the U.S. northeast suffered through its sixth major snowstorm this winter, breaking all snowfall records. http://www.sustainablebusiness.com/index.cfm/go/news.display/id/21789

  2. Lou Grinzo says:

    Great post, Joe.

    While I don’t mean to excuse the media for any part of their contribution to the public’s misunderstanding of this paper, I have to wonder if we’re seeing a two-part psychological effect.

    Part 1 is simply the desire among journalists and everyone else for the climate mess we’ve created to turn out to be not as bad as we know it is. This surely has to incline non-experts, at least slightly, to interpret things like this paper in a more favorable light. “Look — some evidence (for once!) that it’s not worse than we thought it was!”

    Part 2 is their perception, based on experience with non-science topics, that there’s often a pendulum-swing to the news. News erupts about some scandal that sounds awful for a politician or CEO or whomever, and then as more details trickle out of days to months, the situation is seen to be much more nuanced, and in some cases (like the gentleman who was widely believed by the public to be responsible for the Atlanta Olympics bombing, but turned out to be innocent) the initial assessment is completely wrong. I suspect many reporters are seeing this science issue in the same way, and they expect that after the relentless drumbeat of “it’s worse than we thought” news that things “have to” swing back the other way. Of course the news is under no restriction, and as appropriately conservative scientists learn more about the hideous complexities of the Earth System, it’s no surprise that nearly all the news in recent years has been so grim.

    • Peter Mizla says:

      The media never ceases to amaze me- are they ‘desperate’ for something/anything that will make the scientific consensus wrong. Perhaps they are seeking vindication for not reporting to the public the real truth about we face as a civilization. Their analysis of this flawed report thus far is pathetic.

      • Mulga Mumblebrain says:

        The media are serving that business power that owns them, pays their wages and will sack them if they commit thought crime. The MSM owners are the same people, the same caste, the same 0.01% who control the fossil fuel industry, the greatest repository of wealth in history. MSM denialism, misreporting and deliberate confusion is no accident. It is ideology at work, ideology that despises environmentalism and the truths that it reveals. The MSM will NEVER report otherwise, not until it is too late, then they will seek to save their own hides by blaming others and finding new scapegoats.

    • I agree with Lou on both points but especially on the first part. We all want the problem we are too lazy and greedy to do anything about to turn out to be not so bad.

      In fact this psychology is exactly the reason the pathetic arguments of the deniers consistently resonate with the public. Few in the media rise above the animal impulse, just like few in the public.

    • Ernest says:

      I would add a Part 3 psychological effect is the impression that climate change science is still “unsettled science”. (I’ve seen posts to this effect by skeptics on other sites with news of this study, while forgetting that the authors already accept anthropogenic global warming, and what is currently discussed is the variability of sensitivity estimates.) It plays into the “doubt and confusion” strategy of the denialists.

  3. Gail Zawacki says:

    Aside from such distortions this study invites, their model like those used by IPCC ignores amplifying feedbacks such as the albedo effect, and methane release, which are both well underway and unstoppable even if we cease burning fuels today, which we won’t!

    That’s leading inexorably to the death of the forests…from the other emissions – to be exact, pollution – which has never occurred in any significant level before in the paleoclimate, it’s almost wholly manufactured by human-created emissions.

    As the trees and other vegetation die, there goes a major carbon sink, which will lead to a higher rate of accumulation in the atmosphere, which leads to even more warming.

    http://witsendnj.blogspot.com/2011/11/freedoms-just-another-word.html

  4. MarkfromLexington says:

    Thank you for the very thorough review of this paper.

  5. Another excellent example of why your’s is the one indispendable blog. Thanks again.

  6. Joan Savage says:

    Thanks, Joe!

    My first reaction to the Schmittner article was that Last Glacial Maximum had a very different global distribution pattern for where heat accumulation could go, a pattern that differs from today.

    It seems so basic, I apologize in advance for bringing it up.

    As the LGM ended, the accumulation of heat was splitting among a lot of latent heat of fusion (melting the continental glaciers), plus warming the oceans, warming the land, and warming the atmosphere.

    Don’t we all know that if there’s even one ice cube left in the glass, the water stays cool and also affects the air immediately above it?

    This time around there is not a whole lot of ice left to melt, so most of the heat accumulation is in the oceans.

    The next phase change for water has a huge latent heat of evaporation, so it is preceded by a long plateau of water vapor release, and that means clouds, lots of clouds.

    For Schmittner et al.’s admittedly simple model to use LGM as a test data set for a limiting case for climate sensitivity, and leave out clouds to boot, has me nearly laughing, but not.

    • John McCormick says:

      Joe a masterful post.

      Joan, I found this part of your comment most interesting and something I have wondered a good deal about:

      “This time around there is not a whole lot of ice left to melt, so most of the heat accumulation is in the oceans. ”

      Reading up on North Atlantic Oscillation is telling me there is much to be understood quickly about the effects of Arctic meltback influence on NAO.

      NAO is influenced by temperature differences between the Arctic and the equator. As Arctic temps rise, the difference is small and the jet stream is weakened, thus allowing cold Arctic air south. It would appear this is the future for Western Europe and Eastern North America.

      But, in Northern VA, this end of November at sunrise, it is t-shirt weather and a neighbor’s cherry tree was in full bloom last week. Mayhem in the air.

      We need to put pieces together more quickly and I believe observations are more valuable to climate scientists than models if we are concerned about preparing for a Northern hemisphere new regime of winter and spring weather. That is going affect how the world has any reserves of grain in the very near future.

  7. BBHY says:

    The authors of this study are saying that a global change of temperature of only 2.2 degrees is the difference between present conditions and having an ice sheet 2 miles thick covering New York.

    So, even if we assume for the moment that the study is correct, I don’t find it at all comforting that such a small temperature change can cause such drastic changes to our climate.

    I’m not understanding how the media can put such a positive spin on this.

  8. Robert Nagle says:

    Great post. A rhetorical quibble about the headline. Media “misleads” is probably unfair to the science reporter. In retrospect though, Berger should have gotten a quote or two from Dr. Nielsen-Gammon or another person in the field about what it meant. But climate science is hard — and I don’t envy Berger’s job of having to summarize it fairly.

  9. Mike Roddy says:

    The fact that the deniers have jumped all over this quite nuanced study shows just how desperate they have become. By any rational accounting- even before the BEST report was released- they have been getting their butts kicked all year. Just as critical as sensitivity to CO2 is the issue of human caused forcings, another area the deniers have been unable to question with actual evidence. Extreme weather events, global emissions increases, and exposed fossil fuel company bribery are reaching runaway proportions.

    The time is ripe to discredit and abandon the misinformers altogether (hello, MSM). They have no place in such a critical dialogue. Slowly, a few key organs- such as the Post, in spots- are catching on. The people will follow.

  10. Michael A. Lewis says:

    This is a sad commentray on the state of discourse over climate variability. This hyperbole and basic misunderstanding of climate science is shocking.

  11. Tom Yulsman says:

    The Pliocene Epoch, between about 5.3 million and 1.8 million years ago, was the last time we had the same amount of carbon dioxide in atmosphere as we do today, along with the same earth-sun relationship. That means we’re not mixing and apples and oranges in comparing the two climate regimes. And during the Pliocene, sea level was 25 meters higher than it is today.

    This alone, without any need to know the precise sensitivity of the climate to CO2, should tell us that Wally Broecker was spot on: The climate is an angry beast and we’re poking it with sticks.

    Many people who read Joe’s blog no doubt know this. But I think all of us tend to forget that even if we had no computer model projections of future climate, and even if we had no studies like the one discussed here about climate sensitivity, we would still have more than ample reason to be concerned. Very, very concerned.

    • Joe Romm says:

      We agree on this. I should do another post on the paleoclimate record.

    • Lou Grinzo says:

      Agreed, Tom. That’s a very straightforward and compelling way to approach the topic.

      Similarly, I’ve found that an effective way to communicate with those not engaged on the topic is phenology — the study of the timing patterns of when animals migrate, when flowers bloom, etc. We have records going back hundreds of years in some places, thanks to generations of dedicated natural scientists, that show unmistakeable patterns of global-scale warming. (And that’s without invoking the satellite record showing the polar and Greenland ice loss over the last few decades.)

      In person and in e-mail exchanges I’ve said to self-proclaimed skeptics (not deniers) that if they don’t believe what scientists say, then how do they explain the shifts in all these natural cycles? Do they think that plants and animals have been duped by some vast conspiracy of scientists, no doubt started by Newton? It stops them in their tracks every time.

  12. Tony says:

    A quote below from the BBC news report covering this study titled ‘CO2 climate sensitivity ‘overestimated’’

    “But it does mean that to induce large-scale warming of the planet, leading to widespread catastrophic consequences, we would have to increase CO2 more than we are going to do in the near future, he said.
    “But we don’t want that to happen at any time, right?”
    “At least, given that no one is doing very much around the planet [about] mitigating CO2 emissions, we have a bit more time,” he remarked”

    END QUOTE

    Unfortunately many are interpreting these statements to mean that we have more time in which to do nothing. The problem is that we don’t have time. Change must start now. The deeper the hole we dig for ourselves simply means the harder the climb back to the surface.

  13. John McCormick says:

    The psychology of a global warming world is a rambling topic because there is no consensus even in a small group of people what a warming world means to each individual. For some, it is a topic too complex or uncomfortable to discuss. So, avoidance is the easiest route to take.

    Joe, your post was a masterful piece of work and I labored through it to the end. Schmittner’s report will give comfort to all sides depending upon their level of acceptance or denial. A typical science reporter is being carried along by the next report and the reporter has a built-in psychological meter.

    Accepting the full measure of Dr. Hansen’s warning is a pre-requisite for any reporter to produce articles as good as Joe’s posts. Getting to that level of understanding and belief is the reporter’s psychological challenge; getting the editor, wife, neighbor, bowling team to that level presents, for each of them, their own psychological challenge.

    We may soon hear that November was the warmest on record. Next September, the Arctic may also have broken meltback records. We may be adjusting to record breaking but that does not mean our inner voice isn’t telling us something is DIFFERENT out there…can’ say why but the feeling is unsettling.

    Most people will have a hard time reading Joe’s post on the Schmittner report but wearing t-shirts, in end of November in Northern VA is it’s own report…on a psychological level.

  14. Raul M. says:

    another assumption is that even with a failing economy, the oil industries will have enough powers to ensure that the standing oil wells in the gulf of pollution will weather the storms and that even if a mishap happens that it won’t produce lasting harmful effects.
    That the oil has changed the color of the sand even on the Atlantic side over the years reminds me of the old adage. How do you spell assume- start with ass + u + me.
    So it is in the interests of the oil companies to have an idea of will the hurricanes go throughout the gulf during an el niño year and what would that mean?
    I think that the opportunity to prepare is now while the weather is calmer.
    Although, we still remember the claims that it was unforeseeable and an act of god the sand isn’t so clean for those who still like to stick their head to it.
    And the oil slicked hair do for the beach goers…

    • Raul M. says:

      Oh, I guess the nice ladies with the nice children are not allowed to talk about the need to replace the carpet in the condo if the children and family do go and spend the day on the shore. Yes thousands of dollars on that condo rental carpet for a day at the shore could turn into mayhem.

  15. Great post, Joe. Thanks for assembling all this.

  16. Kim Viner says:

    Thanks Joe. This certainly answers my questions from yesterday.

  17. Martin Palmer says:

    My reaction upon reading about this study was to wonder about rates of change.

    Does the earth really have a single climate sensitivity to a doubling of CO2, no matter how rapid the change is?

    If methane is evolved slowly enough, for example, it really is not much of a problem. It is oxidized into CO2 harmlessly, and the carbon disposed of as carbonate by the rock weathering cycle.

    But in our current situation, we are changing CO2 concentrations faster than they have ever been changed before, except in the aftermath of a major meteor impact.

    The scenario in which latent positive feedback loops are activated by the suddenness of the change, and methane starts to evolve faster than it can be oxidized, overwhelming the hydroxyl radical, remains intact, I think.

    Isaksen – Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions

    So, I wonder if we are being misled by our own terminology, in seeking a single sensitivity number for the climate system, regardless of rates of change. One can certainly see how the oceans, permafrost, and methane hydrates could react totally differently to a fast rate of change of CO2 versus a slow one.

  18. Even if this study turns out to be correct (and the article points out all the reasons why it likely isn’t) the mean climate sensitivity would still spell disaster. The MIT study that Joe and I are so fond of (Sokolov et al 2009) shows that by 2100 we’re in for more than TWO doublings of greenhouse gas equivalent concentrations compared to preindustrial times if current trends continue. That means at least 2 x 2.3 deg C/K = 4.6 degrees C increase, or 8.3 degrees F average warming. This is not a pretty picture.

    Sokolov, A.P., P.H. Stone, C.E. Forest, R. Prinn, M.C. Sarofim, M. Webster, S. Paltsev, C.A. Schlosser, D. Kicklighter, S. Dutkiewicz, J. Reilly, C. Wang, B. Felzer, J. Melillo, and H.D. Jacoby. 2009. Probabilistic Forecast for 21st Century Climate Based on Uncertainties in Emissions (without Policy) and Climate Parameters. Cambridge, MA: Massachusetts Institute of Technology (MIT) Joint Program on the Science and Policy of Climate Change. 169. January. [http://globalchange.mit.edu/files/document/MITJPSPGC_Rpt169.pdf]

  19. dana1981 says:

    Good post Joe. Here’s the link to the Skeptical Science post, which I don’t see above:

    http://www.skepticalscience.com/Schmittner-climate-sensitivity-goood-bad-ugly.html

    The bottom line here is that the Schmittner et al. marginally lower sensitivity is only correct if MARGO is correct about the LGM being warmer than we currently think. Given the many other lines of evidence that sensitivity is ~3°C for 2xCO2, it’s far more likely that MARGO simply underestimates the glacial cooling, as Dr. Alley noted.

  20. EDpeak says:

    Was just about to head to CP anyway when (JR will be glad to here) my “cast the net much more broadly” regularly scheduled Google News Alert for

    “ppm 2008 climate OR warming 2.3 OR 2.28″

    found this CP post, good, about to dive into reading it now!

  21. Dr. Thomas Pringle says:

    It looks to me like folks here have not noticed or read the nicely written commentary piece in the very same 24 Nov 2011 forthcoming Science by Hegerl and Russon:

    http://www.sciencemag.org/content/early/2011/11/22/science.1214828.full.pdf