by Judith Curry
I’ve just returned from China, the first thing I did in the U.S. airport on my layover back to Atlanta was to check twitter.
I’m feeling pretty brain dead after my flight and the 12 hour time change. Checking my twitter notifications that have accrued over the past 11 days while I’ve been in china (behind the great Chinese internet firewall) was very entertaining.
Overall my WSJ op-ed seems to have been well received. Below are some of the more interesting or entertaining of the critical responses.
My post on the Lewis and Curry paper was reproduced at the Climate Change National Forum, Bart Verheggen responds [here]. Excerpt:
I’m pleased that Dr. Curry acknowledges that “uncertainty in itself is not a reason for inaction”. I do find that conclusion slightly at odds with her frequent calls to put less effort in mitigation. Curry says that “deep uncertainties remain”, while at the same time apparently basing her anti-mitigation viewpoint on the assumption that climate sensitivity (ECS) is low. If this deep uncertainty however extends to ECS, one would think that the risk of substantial warming entails a substantial risk that is worth hedging against. Is she so sure that ECS is low and impacts benign? In short, I sense some inconsistencies in her approach to uncertainty.
It appears to me that Dr Curry is at times inflating the uncertainty, to the point of creating the appearance of ignorance. I think that does a disservice to the prospect for “a more meaningful dialogue on how to address the complex challenges of climate variability and change”, which is a goal she frequently expresses to strive towards. As an example of inflated uncertainty, it is imho well established that the warming since 1950 is predominantly anthropogenic, and likewise is the projection that the warming will continue with continuing emissions very robust. There are uncertainties and ranges of probability, but the impression that this is totally up in the air is mistaken, to my mind. Perhaps in her (to my mind mistaken) belief that uncertainties are frequently ignored, she started over-compensating in the other direction?
JC comment: My seeming contradictory stance on the uncertainty issue is a valid point to raise. We have very little justification (and no demonstrated skill so far) for predicting the climate of the 21st century. That said, within the framework of how the IPCC is framing the climate problem and has defined ‘climate sensitivity’, the only justification for values of ECS (greater than 3 C) is climate models that that do not adequately account for natural internal variability and when compared with observations seem to be running ‘too hot.’ So, could climate sensitivity be very high? Yes, but we have no reliable methods for inferring very high climate sensitivity, other than climate models that are demonstrably running to hot and dubious analyses of the paleoclimate record.
The paleo-estimates are interesting in the sense that from a variety of time periods and from a variety of studies and methods, ECS appears to be in the range between 2 and 4 degrees C. It thus seems that when someone advocates for a value lower than that, they have some explaining to do as to why such large temperature swings occurred in the (deep) past?
JC comment: Yes lets use dubious paleo estimates to falsify estimates from the relatively reliable instrumental record, and also lets forget that climate sensitivity is state dependent.
Rapid Response Team
Michael Mann, John Abraham, Scott Mandia, Peter Gleick and Richard Somerville have penned a response at HuffPo: Curry advocates against action on climate change. Excerpts:
So the piece repeats the same tired claims about lowered sensitivity, using the “pause” meme and her own study as justification for delaying action. According to her (and of course the contrarians) a limited set of studies using a single incomplete methodology are reason enough to put off getting serious about climate change.
To summarize the article, it turns out that even if one assumes these recent studies are correct, this buys us only a decade of extra time before crossing the internationally agreed-upon limit of 2°C of warming. This means that even if Curry’s correct, it may just be the difference between bad and terrible consequences of our inability to get emissions under control.
This understanding is shared by all the mainstream climate scientists who have examined the breadth of the scientific literature.
Esoteric and academic arguments about the response of the atmosphere to a doubling of CO2 may be interesting for those steeped in the peer-reviewed literature, but for the public and policy makers the important and unfortunate fact is that climate change is continuing unabated. This was the hottest September on record, after the hottest August on record (yielding the hottest summer on record), and the oceans continue to warm rapidly. In fact, some parts of the ocean have been shown to be warming even more rapidly than we thought.
JC comments: Pause denial is getting more and more difficult with time.
In the end, Curry’s claims fly in the face of what we know. Quite literally, according to the largest scientific organization in the world and publisher of the journal Science. The American Association for the Advancement of Science (AAAS) released this year a report titled “What We Know” that shows that taking action now reduces both the cost and the risks associated with our warmed world.
Regardless of whether Curry is right about the climate being slightly less sensitive to CO2 (something that hundreds of thousands of years of paleoclimate records suggest is false) the fact remains that the sooner we reduce emissions, the less damage we will endure. And interestingly, Curry admits that the only substantial worry is from a high emissions scenario. But if we listen to her argument for inaction, that high emissions scenario is exactly what we’ll get.
JC comment: The signatories on this op-ed are interesting; in the old days the Rapid Response Team would have been able to pull a larger number and more impressive names as signatories. This is really a very content free op-ed, they didn’t even manage to insert any good ‘smears.’
Union of Concerned Scientists
Union of Concerned Scientists has an article: Wall Street Journal offers a skewed climate change perspective from Judith Curry. Excerpts:
I asked my colleague Peter Frumhoff—our chief scientist, a former IPCC lead author, and the co-author of a recent study on climate science and policy—if I could share his reaction to Dr. Curry’s argument.
Here’s what he wrote:
The ocean is absorbing much of the excess heat from human emissions. If the model Curry and colleagues discussed had incorporated the latest ocean heat content data, their relatively low best estimate for climate sensitivity would have been more in line with previously reported, higher estimates.
It would be a mistake to set policy based solely on low estimates. That’s why we have advisory bodies like the IPCC and National Climate Assessment that examine all the available science, including higher estimates. The risks of far greater climate sensitivity can’t simply be discounted or dismissed.
The bottom line is that we know enough about where we’re heading to reduce emissions even as scientists grapple with homing in on precisely how much the Earth is expected to warm.
DeSmog blog has a guest post by Climate Nexus Judith Curry is back advocating for inaction in the Wall Street Journal. Excerpts:
Curry provides a highly biased and skewed overview of climate sensitivity studies, which makes sense for publication in the Wall Street Journal. In reality, the IPCC sensitivity estimate remains the most reliable and comprehensive expression of the state of knowledge on the topic, and scientists agree that this sensitivity range implies an urgent need for climate action.
Curry has growing ties to denier groups and her consulting business serves fossil fuel companies. She recently participated in a forum held by the discredited, fossil-fuel funded George Marshall Institute, which advocates outright climate denial and has denied the link between tobacco and cancer in the past. Her consulting company has received funding from the fossil fuel industry since 2007, at her own admission. Finally, her work has been repeatedly criticized by reputable scientists including those at RealClimate and the Union of Concerned Scientists.
JC comment: Well if you can’t come up with any real arguments, you can also try playing the fossil fuel card.
Lewandowsky has an article in the Conversation Why climate uncertainty is no excuse for doing nothing. Relevant excerpt:
Paterson is far from alone: climate change debate has been suffused with appeals to “uncertainty” to delay policy action. Who hasn’t heard politicians or media personalities use uncertainty associated with some aspects of climate change to claim that the science is “not settled”?
Over in the US, this sort of thinking pops up quite often in the opinion pages of The Wall Street Journal. Its most recent article, by Professor Judith Curry, concludes that the ostensibly slowed rate of recent warming gives us “more time to find ways to decarbonise the economy affordably.”
Lucia notes the inconsistency in a post Lew: Curry’s paper suggests LESS uncertainty not MORE! As I stated above, with the confines of the narrow way that the IPCC frames the climate change problem, the evidence is growing that we can chop off the fat tail of previous high sensitivity estimates.
Greg Laden has a post Mark Steyn and Judith Curry. Relevant excerpt: “Two items related only because these two seem to like each other and there are coeval happenings.”
JC comment: I guess if you don’t have any real arguments against my article, you can always criticize me for the company I keep.
The Australian has a superb article by Graham Lloyd: A pause for this message: climate change numbers aren’t adding up. Excerpts:
It is a crucial time for science. Garth Paltridge, former chief research scientist with the CSIRO Division of Atmospheric Research and chief executive of the Antarctic Co-operative Research Centre, fears the rise of “postmodern” science. In the world of postmodern science, he says, results are valid only in the context of society’s beliefs, and where the very existence of scientific truth can be denied. “Postmodern science envisages a sort of political nirvana in which scientific theory and results can be consciously and legitimately manipulated to suit either the dictates of political correctness or the politics of the government of the day,” Paltridge says.
At this point, Australian governments and their climate agencies are standing firmly behind the IPCC. But respected US climate scientist Judith Curry agrees with Paltridge.
Curry has been a strong voice in the climate change debate internationally and is at the centre of new research that questions climate sensitivity. She argues the sensitivity of the climate to increasing concentrations of carbon dioxide is a central question in the debate on the appropriate policy response to increasing carbon dioxide in the atmosphere. In the US, she says, a climate policy dialogue is starting to open up, with discussion of the 2C threshold, lower sensitivity and the hiatus.
Inquirer put a series of questions to Australia’s high-profile climate change bodies asking them to comment on Curry’s research on climate sensitivity, the hiatus in global surface temperatures and model predictions. Former climate commissioners Will Steffen and Tim Flannery were unavailable to answer but Climate Council chief executive Amanda McKenzie says “vested interests have been using the ‘so-called pause’ to spread doubt and misinformation”. “The Earth continues to warm strongly,” she says. “Since 1998 human activities have introduced two billion Hiroshima bombs’ worth of heat into the atmosphere.”
Responses from Australia’s key science organisations show they remain in lock-step with the IPCC and their advice is accepted by Environment Minister, Greg Hunt. Helen Cleugh, science director at CSIRO Oceans and Atmosphere Flagship, says measurements do show that the rate at which global mean surface temperature has warmed in the past decade is less than the previous decade. However, while the rate of increase is lower, the temperatures are not lower, she says.
Measurements across the oceans and Earth system as a whole show that warming has continued unabated. “A reduction in the rate of warming (not a pause) is a result of short-term natural variability, ocean absorption of heat from the atmosphere, volcanic eruptions, a downward phase of the 11-year solar cycle, and other impacts over a short time period,” Cleugh says.
After taking advice from the Bureau of Meteorology, Hunt tells Inquirer the warming of the climate system is “unequivocal”. “The climate system, which includes the atmosphere, oceans, land and ice has continued to accumulate heat over the last 18 years,” Hunt says. Although there has been a slower rate of atmospheric warming during the past 18 years, this does not undermine the fundamental physics of global warming, the scientific basis of climate models or the estimates of climate sensitivity.
Greens leader Christine Milne says she does not accept the pause. “There has been a slowdown in the speed of the rise but global surface temperatures have still continued to climb,” Milne says. “There are strong indications through observations and models that the ocean is absorbing more of the heat than it has in the recent past.”
In Britain, the Met Office has acknowledged the pause and debate about its significance. “Global mean surface temperatures rose rapidly from the 1970s but have been relatively flat over the most recent 15 years to 2013,” the Met says. “This has prompted speculation that human induced global warming is no longer happening, or at least will be much smaller than predicted. Others maintain that this is a temporary pause and that temperatures will again rise at rates seen previously,” the Met says.
But the Met Office says research shows the recent pause in global surface temperature rise does not materially alter the risks of substantial warming of the Earth by the end of this century. “Nor does it invalidate the fundamental physics of global warming, the scientific bases of climate models and their estimates of climate sensitivity,” the Met says.
Australia’s Bureau of Meteorology says the rate of warming in global surface temperature during the past century has not been uniform, with some decades warming more rapidly than others. “This is a consequence of variations in heat exchange between the atmosphere and the oceans, and other decade-to-decade changes like variations in solar forcing and the solar dimming effects of pollution and volcanic eruptions,” BoM says. “The pattern that results is one of steady warming of the oceans, accompanied by alternating periods of fast and slow rises in air temperature.”
There is dispute over whether increased ocean heat can fully explain the absence of surface warming during the past 18 years. Recent papers have claimed greater deep ocean heat in the north Pacific, Atlantic and Southern Ocean to explain the “missing” heat. According to Curry, the bottom line is that uncertainties in ocean heat content are very large, and “there is no particularly convincing evidence that the “missing heat” is hiding in the ocean.
“The three studies represent careful studies using conventional assumptions relating to climate sensitivity, addressing the question ‘where has the heat in a warming earth gone?’ ” Asten says. “An alternative approach which I predict will come, although not without opposition from ‘consensus scientists’, is to postulate that the ‘missing heat’ was never here; that is, a reduced climate sensitivity will be estimated for the Earth, at or below the low end of the range currently published by the IPCC.”
Asten says the trend of climate sensitivity estimates made across the past six years from meteorological, satellite and ocean sediment records has been, with very few exceptions, to produce estimates at or below the low end of the range published by the IPCC. He says low values of climate sensitivity will still affect global temperatures as CO2 concentrations in the atmosphere rise, but increases in temperature may be of similar magnitude to naturally driven temperature cycles, a scenario that has strong implications for how we manage causes and consequences of climate change.
Paltridge says that the prospect of “missing heat” being located in the oceans is a double-edged sword. “We are being told that some internal oceanic fluctuation may have reduced the upward trend in global temperature,” he says. “It is therefore more than a little strange that we are not hearing from the IPCC that some natural internal fluctuation of the system may have given rise to most of the earlier upward trend.
“In light of all this, we have at least to consider the possibility that the scientific establishment behind the global warming issue has been drawn into the trap of seriously overstating the climate problem in its effort to promote the cause. It is a particularly nasty trap in the context of science because it risks destroying, perhaps for centuries to come, the unique and hard-won reputation for honesty which is the basis of society’s respect for scientific endeavour.”
Climate science has been thrown into disarray by the hiatus, disagreement between climate model and instrumental estimates of climate sensitivity, uncertainties in carbon uptake by plants, and diverging interpretations of ocean heating (in the face of a dearth of observations). ‘Certainty’ arguably peaked at the time of the AR4 (2007); perception of uncertainty is arguably greater than any time since the FAR (1991). Yes of course we know more about the climate system than we did in 1991, but more knowledge about the complex climate systems opens up new areas of ignorance and greater uncertainty.
In context of the way climate sensitivity is defined by the IPCC, uncertainty in climate sensitivity is decreasing as errors in previous observational estimates are identified and eliminated and model estimates seem to be converging more. Climate model simulations, when compared with 21st century observations seem to be running too hot, giving creedence to the lower observation-based sensitivity values.
What do the lower values of climate sensitivity imply for policy? Well slower values of warming make it easier to adapt, and provide time to develop new technologies and new policies. But the true believers such as Mann et al. call adaptation, developing new technologies and policies as ‘inaction.’ The policy logic apparent in the essays critical of my op-ed are rather naive.
So we are left with science in disarray and naive logic regarding policy. And the ‘warm team’ wonders why people are yawning?