From Oregon State University some news the team and especially Kevin Trenberth just really don’t want to hear. I covered this on a tip from Dr. Pat Michaels back on Nov 9th titled: Climate sensitivity- lowering the IPCC “fat tail” and now the official press release makes the publication well known. Their estimate is 2.4C for a doubling of CO2, which is still higher than Spencer and others have estimated but significantly lower than IPCC’s projections. A link to the paper follows below.
Climate sensitivity to CO2 more limited than extreme projections
CORVALLIS, Ore. – A new study suggests that the rate of global warming from doubling of atmospheric carbon dioxide may be less than the most dire estimates of some previous studies – and, in fact, may be less severe than projected by the Intergovernmental Panel on Climate Change report in 2007.
Authors of the study, which was funded by the National Science Foundation and published online this week in the journal Science, say that global warming is real and that increases in atmospheric CO2 will have multiple serious impacts.
However, the most Draconian projections of temperature increases from the doubling of CO2 are unlikely.
“Many previous climate sensitivity studies have looked at the past only from 1850 through today, and not fully integrated paleoclimate date, especially on a global scale,” said Andreas Schmittner, an Oregon State University researcher and lead author on the Science article. “When you reconstruct sea and land surface temperatures from the peak of the last Ice Age 21,000 years ago – which is referred to as the Last Glacial Maximum – and compare it with climate model simulations of that period, you get a much different picture.
“If these paleoclimatic constraints apply to the future, as predicted by our model, the results imply less probability of extreme climatic change than previously thought,” Schmittner added.
Scientists have struggled for years trying to quantify “climate sensitivity” – which is how the Earth will respond to projected increases of atmospheric carbon dioxide. The 2007 IPCC report estimated that the air near the surface of the Earth would warm on average by 2 to 4.5 degrees (Celsius) with a doubling of atmospheric CO2 from pre-industrial standards. The mean, or “expected value” increase in the IPCC estimates was 3.0 degrees; most climate model studies use the doubling of CO2 as a basic index.
Some previous studies have claimed the impacts could be much more severe – as much as 10 degrees or higher with a doubling of CO2 – although these projections come with an acknowledged low probability. Studies based on data going back only to 1850 are affected by large uncertainties in the effects of dust and other small particles in the air that reflect sunlight and can influence clouds, known as “aerosol forcing,” or by the absorption of heat by the oceans, the researchers say.
To lower the degree of uncertainty, Schmittner and his colleagues used a climate model with more data and found that there are constraints that preclude very high levels of climate sensitivity.
The researchers compiled land and ocean surface temperature reconstructions from the Last Glacial Maximum and created a global map of those temperatures. During this time, atmospheric CO2 was about a third less than before the Industrial Revolution, and levels of methane and nitrous oxide were much lower. Because much of the northern latitudes were covered in ice and snow, sea levels were lower, the climate was drier (less precipitation), and there was more dust in the air.
All these factor, which contributed to cooling the Earth’s surface, were included in their climate model simulations.
The new data changed the assessment of climate models in many ways, said Schmittner, an associate professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. The researchers’ reconstruction of temperatures has greater spatial coverage and showed less cooling during the Ice Age than most previous studies.
High sensitivity climate models – more than 6 degrees – suggest that the low levels of atmospheric CO2 during the Last Glacial Maximum would result in a “runaway effect” that would have left the Earth completely ice-covered.
“Clearly, that didn’t happen,” Schmittner said. “Though the Earth then was covered by much more ice and snow than it is today, the ice sheets didn’t extend beyond latitudes of about 40 degrees, and the tropics and subtropics were largely ice-free – except at high altitudes. These high-sensitivity models overestimate cooling.”
On the other hand, models with low climate sensitivity – less than 1.3 degrees – underestimate the cooling almost everywhere at the Last Glacial Maximum, the researchers say. The closest match, with a much lower degree of uncertainty than most other studies, suggests climate sensitivity is about 2.4 degrees.
However, uncertainty levels may be underestimated because the model simulations did not take into account uncertainties arising from how cloud changes reflect sunlight, Schmittner said.
Reconstructing sea and land surface temperatures from 21,000 years ago is a complex task involving the examination of ices cores, bore holes, fossils of marine and terrestrial organisms, seafloor sediments and other factors. Sediment cores, for example, contain different biological assemblages found in different temperature regimes and can be used to infer past temperatures based on analogs in modern ocean conditions.
“When we first looked at the paleoclimatic data, I was struck by the small cooling of the ocean,” Schmittner said. “On average, the ocean was only about two degrees (Celsius) cooler than it is today, yet the planet was completely different – huge ice sheets over North America and northern Europe, more sea ice and snow, different vegetation, lower sea levels and more dust in the air.
“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,” he added.
Schmittner said continued unabated fossil fuel use could lead to similar warming of the sea surface as reconstruction shows happened between the Last Glacial Maximum and today.
“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.”
Other authors on the study include Peter Clark and Alan Mix of OSU; Nathan Urban, Princeton University; Jeremy Shakun, Harvard University; Natalie Mahowald, Cornell University; Patrick Bartlein, University of Oregon; and Antoni Rosell-Mele, University of Barcelona.
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Here’s the paper:
http://www.princeton.edu/~nurban/pubs/lgm-cs-uvic.pdf
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The process of “walking back the cat” has begun. It will be interesting.
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Bill Illis says:
November 26, 2011 at 4:39 am
The science has been hiding behind TCR for several years now but it is only equivalent to a delay between 0 to 7 years at today’s rates.
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Exactly. I’ve noticed several times that Mosher continues having a serious misconception about this. The transient response on land is quite short — 2 yrs at most. Ocean response is longer (10 yrs, especially near the poles & over deep water), but most people live on land last time I checked…
What I read here is:
1. At high sensitivities, observations of glacial advances aren’t enough.
2. At low sensitivities, observations of glacial advances are too much.
3. At moderate sensitivities, observations of glacial advances are just right.
Goldilocks has found a scenario that matches expectations to observation. However, what was found was just ONE matching scenario. We could have done cloud cover mathematics that did as well, and that that would not have been proof of anything other than one set of parameters with a certain set of assumptions fit the data.
The Gore-Mann-Hansen-IPCC position is that there is a unique solution, and that unique solution is CO2. Any geologist will tell you that he can create multiple, internally consistent stories with the same datapoints if the datapoints are not reasonable dense and distributed reasonably according to what he he is looking for. Yes, a 2.4C result can be calculated for a doubling of CO2, but that doesn’t mean that a doubling of CO2 will result in a 2.4C (or other) temperature rise. Just that, with certain assumptions, the math works.
Temperature rises and drops can be brought on with a number of mechanisms; the demand is that the truly unique signatures of CO2 must be found to eliminate the other, overlapping, factors. The tropospheric heat blob was supposed to be one, as was the proportionate heat content of the shallow oceans. Neither has been seen, yet this has not weakened the alarmists’/believers’ positions socially. The concept of non-unique solutions appears beyond the intellectual tolerance for uncertainty of the anti-CO2, anti-captialist, anti-energy fan.
The conclusions that come out of this re-work will be completely misinterpreted as predictions of will happen with a doubling of CO2. All that has been done is constrain the mathematics upon which the assumptions act. The narrowing of possible outcomes is good, of course, as it leaves less wiggle space for observations to fit into. But still there is nothing in this to say that CO2 is responsible in its majority (or entierty) for the observed 20th century global temperature rise.
All focus should be on the signs unique to CO2. Of course, such a thing would shift focus to the true uncertainty of the threat of CO2. Which, right now, is socially, politically and, funding-wise, unacceptable.
It’s curious to see how various AGW skeptics position themselves when such studies come out. It says a great deal about what kind of skeptic they are. On one hand, do they accept the results of the study and admit that doubling CO2 will affect future global temperatures in a statistically significant way (even if less than the 3C increase for a doubling that some warmists would posit), or do they ignore the study and continue on with the mantra that this is just “another model” and nothing to do with reality?
Regarding the study itself, though I’ve only read the abstract and the supplemental materials and methods, it seems the study is a very decent attempt to reduce uncertainty in ECS (estimate of climate sensitivity) to a doubling of CO2, however, the authors themselves recognize the limitations of their own study and clearly list them, such assumptions in dealing with dust, vegetation, etc., and the overall the potential for nonlinear responses not captured in the parameters. These nonlinear responses, for example, could include the response of permafrost to the geologically rapid release of CO2, with the added positive feedback effect of the additional release methane over. This nonlinear response is of course tied directly to difficulty in modeling a system existing on the edge of chaos, meaning that trying to ascertain ECS by looking at the response of the climate during the last glacial maximum, might not be as valid as looking at it during the last interglacial, or perhaps even better, the last time CO2 was at the levels we see today, which was during the mid-Pliocene. Still, I can applaud their efforts in attempting to reduce uncertainty in ECS for a doubling of CO2.
RE: James Sexton: (November 25, 2011 at 8:12 am)
REF: Spector: (November 25, 2011 at 7:58 am)
Someday, I suspect that someone will discover a more compelling climate thermal forcing factor than today’s usual suspect, CO2. It will probably be hailed as a great discovery.
“===============================================================
Yeh, probably something esoteric like the sun and clouds.”
Or something obscure like the optical reflectivity due to the species of oceanic algae that happens to be predominant at any given time. There might even be a cyclic feedback effect if the more reflective species became more abundant in warmer water.
R Gates – your last comment, ending “ ….. I can applaud their efforts in attempting to reduce uncertainty in ECS for a doubling of CO2 sounds reasonable and reasoned, but like the paper it is based on the assumption that the observed temperature changes were caused by CO2. Until that premise can be established, the paper is meaningless.
Has it ever occurred to you that the years and years of expensive effort to evaluate climate sensitivity have resulted in failure simply because the whole exercise is based on a false premise. I submit that the exercise has failed so consistently and for so long that this is now the most likely explanation.
Mike Jonas says:
November 26, 2011 at 2:57 pm
R Gates – your last comment, ending “ ….. I can applaud their efforts in attempting to reduce uncertainty in ECS for a doubling of CO2 sounds reasonable and reasoned, but like the paper it is based on the assumption that the observed temperature changes were caused by CO2. Until that premise can be established, the paper is meaningless.
Has it ever occurred to you that the years and years of expensive effort to evaluate climate sensitivity have resulted in failure simply because the whole exercise is based on a false premise. I submit that the exercise has failed so consistently and for so long that this is now the most likely explanation.
____
I’m not sure exactly what you’re disputing here. Are you questioning:
1) That the climate has any sensitivity to CO2 levels at all?
2) That we should try to establish what those sensitivity levels are?
If CO2 were the only factor at work in the climate, or if that response were simply linear, or if there were feedback processes, both negative and positive at work, or if the climate were not a system existing on the edge of chaos, with small inputs leading to big effects over short and long time frames, then the estimate of sensitivity to CO2 changes would not be an issue. But as all these factors are part of the climate system, the sensitivity of the climate to changes in CO2 remains a key issue…if not THE key issue in current climate research.
Gates,
I’ve repeatedly challenged you [and anyone else] to try and falsify my testable hypothesis:
At current and projected concentrations, CO2 is harmless and beneficial.
Simple, straight to the point, testable, and falsifiable. Using the Scientific Method, show us empirical evidence of global harm due to human CO2 emissions. Make sure the global damage is quantifiable, and directly traceable specifically to human CO2 emissions.
So far, the only thing I’ve heard are crickets chirping; the hypothesis remains standing. But by all means, try to falsify it if you can. Just make sure you provide solid, verifiable evidence of global harm from CO2. Models don’t count, because they’re models. They are programmed by folks with a vested interest in the outcome, and they are certainly not evidence.
The fact is that CO2 is harmless, and beneficial to the biosphere. More is better. More [natural] warming is better, too. A 2° – 3°C rise would be good for everyone.
Smokey says:
November 26, 2011 at 3:52 pm
At current and projected concentrations, CO2 is harmless and beneficial.
——
Not a hypothesis Smokey, but with a bit more refinement, it might be. Define the terms harmless and beneficial in scientific terms and exactly for whom they would apply, and you might have the beginnings of something you could test.
And by the way, you seem to think I would disagree with this hypothesis (once you get it fully formulated) which is perhaps one more assumption that you might want to test.
It’s OK Gates, no one else has accepted the challenge, either. You say: “Define the terms harmless and beneficial in scientific terms…” That’s just rhetoric. My handy online dictionary defines harm as:
• material damage : it’s unlikely to do much harm to the engine.
As for beneficial, that’s just as easy. I’ve posted numerous links showing that trees and crops grow faster and require less water when CO2 rises. Beneficial, no?
And yes, I do think you would disagree with that hypothesis… if you could find any evidence of global harm from the rise in CO2. Since you can’t, you hair-split definitions.
So why not just admit that the “carbon” scare is baseless?
Smokey is spot on.
It’s the job of the R. Gates’ of the world to do the work.
You’re the folks claiming planetary crisis.
One of your tasks is to get a job with a greenhouse grower who uses CO2
Here’s a primer for you.
http://www.omafra.gov.on.ca/english/crops/facts/00-077.htm
“Ambient CO2 level in outside air is about 340 ppm by volume. All plants grow well at this level but as CO2 levels are raised by 1,000 ppm photosynthesis increases proportionately resulting in more sugars and carbohydrates available for plant growth.
Any actively growing crop in a tightly clad greenhouse with little or no ventilation can readily reduce the CO2 level during the day to as low as 200 ppm.
The decrease in photosynthesis when CO2 level drops from 340 ppm to 200 ppm is similar to the increase when the CO2 levels are raised from 340 to about 1,300 ppm (Figure 1).
As a rule of thumb, a drop in carbon dioxide levels below ambient has a stronger effect than supplementation above ambient.”
R. Gates says:
November 26, 2011 at 5:03 pm
=======
Well, if nothing else, I would say R. Gates is at the top of his game.
Nice to see it.
Smokey says:
November 26, 2011 at 5:19 pm
It’s OK Gates, no one else has accepted the challenge, either. You say: “Define the terms harmless and beneficial in scientific terms…” That’s just rhetoric. My handy online dictionary defines harm as:
• material damage : it’s unlikely to do much harm to the engine.
As for beneficial, that’s just as easy. I’ve posted numerous links showing that trees and crops grow faster and require less water when CO2 rises. Beneficial, no?
And yes, I do think you would disagree with that hypothesis… if you could find any evidence of global harm from the rise in CO2. Since you can’t, you hair-split definitions.
So why not just admit that the “carbon” scare is baseless?
______
A nice start Smokey. You seem to be focusing on what increased CO2 will do for “trees” and “crops”. So I suppose that you are then putting all plants into the mix and suggesting that all flora on the planet will not be harmed by higher levels of CO2 in the atmosphere? Are you lumping in fauna as well? Are you including levels in both the atmosphere and oceans? Are you including the flora and fauna of the oceans in your “do no harm” and “beneficial” quasi-hypothesis for increasing levels of CO2?
In term of the precision required to become a true hypothesis, which you claim are hair-splitting– sorry, but that’s what is required.
Finally, you are completely wrong in your continued assumption that I believe in catastrophic AGW. I would challenge you to find one post where I stated that I believe that to be the case. Especially if the sun does enter into a sleepy Maunder-type minimum, Europe and New England at least will be very happy for the extra bit of help from the additional CO2 to prop up temperatures.
Robert in Calgary says:
November 26, 2011 at 5:28 pm
Smokey is spot on.
It’s the job of the R. Gates’ of the world to do the work.
You’re the folks claiming planetary crisis.
_____
Sorry, but I’m not the “folks” claiming any sort of crisis. I simply have stated that I believe humans are causing climate change.
One may “believe” anything they wish, I suppose. But here’s the thing: Climate ALWAYS changes and always has. I think it is fair to say that we are possibly still in recovery from the LIA as temperatures have still not recovered to what they were prior to that event according to agricultural chronicles of the time. We still can’t grow some crops in the places they were growing during the MWP.
But more importantly, the data should be quite obvious but it isn’t. We still have these “scientists” arguing among themselves if their presentations are even credible. Sure, in their public face they all stand unified, but in private they aren’t. Just no single one of them wants to be the guy that kills the golden goose.
There is still no good evidence that climate is warming any faster than it has in the past. It certainly isn’t warmer than it has been in the documented past. You can “believe” anything you wish to believe. Matters of faith are often immobile to logic. That’s fine but state it for what it is. It isn’t based on science. The science says we still don’t have any observational evidence of AGW.
Why haven’t temperatures exceeded 1933? It’s been 78 years, we still haven’t exceeded it (yeah, I know, some records were recently adjusted AGAIN to make 1933 a little cooler and make 1998 a little warmer so that the 1998 temperatures would very, very slightly exceed 1933 but those are “adjustments” coming long after the fact produced by people with a vested interest in those adjustments) But we certainly don’t have any global hockey stick going on.
It just isn’t happening.
RE: Mike Jonas: (November 26, 2011 at 2:57 pm)
“Has it ever occurred to you that the years and years of expensive effort to evaluate climate sensitivity have resulted in failure simply because the whole exercise is based on a false premise. I submit that the exercise has failed so consistently and for so long that this is now the most likely explanation.”
Perhaps that false premise or bias was the environmentalist belief that poisonous chemicals produced by modern industry were causing irreversible damage to our environment and the modern (post normal) scientist has a duty to make the public aware of this, compounded by the propensity of those holding this belief to take up environmental sciences as their life’s work.
The CO2 sensitivity from the ice ages cannot be determined unless one also uses an accurate estimate for the solar radiation that the Earth absorbed at the time
This is a chart showing what the current Solar Forcing is by Latitude and what this study used (and what Hansen and R. Gates and all the climate model studies use).
It is deliberately modeled far too high so that more of the reduction in temperatures can be ascribed to CO2/GHG.
http://img9.imageshack.us/img9/2845/solarforcingcurrentvslg.png
As I said would happen with the study, SkepticalScience and others are already saying they used too small of a temperature decline, they used the poor University of Victoria climate model, they missed the regional temperatures by a wide margin. It should have produced 3.0C per doubling.
http://www.skepticalscience.com/Schmittner-climate-sensitivity-goood-bad-ugly.html
The article is, of course, completely wrong because they have deliberately on purpose, underestimated the Albedo change from all that glacial ice, sea ice, snow, desert and grassland.
As others have mentioned above, it’s a moot point studying sensitivity issues when the real problem is with the models.
Please visit Dr. Roger Pielke Sr.’s blog for a more thorough scientific discussion. But his conclusion, along with other world renowned scientists with published papers on the subject, is, “Global and regional climate models have not demonstrated skill at predicting regional and local climate change and variability on multi-decadal time scales.”
In the paper, “A Comparison of Local and Aggregated Climate Model Outputs with Observed Data. (G. G. Anagnostopoulos, D. Koutsoyiannis, A. Christofides, A. Efstratiadis & N. Mamassis (2010): Hydrological Sciences Journal, 55:7, 1094-1110 1094-1110), it states in the conclusions:
“However, we think that the most important question is not whether GCMs can produce credible estimates of future climate, but whether climate is at all predictable in deterministic terms.”
These dire “predictions” of future temperature increases are spurious if the science of the models themselves is erroneous.
Gates opines:
“You seem to be focusing on what increased CO2 will do for “trees” and “crops”. So I suppose that you are then putting all plants into the mix and suggesting that all flora on the planet will not be harmed by higher levels of CO2 in the atmosphere? Are you lumping in fauna as well? Are you including levels in both the atmosphere and oceans? Are you including the flora and fauna of the oceans in your “do no harm” and “beneficial”… & etc.
Not one bit of evidence showing any global harm from CO2. Just rambling nonsense as usual. But I appreciate your admitting that you believe humans are causing climate change. Belief is all you’ve got, while skeptics have plenty of empirical evidence to back up our skepticism.
Humans cause regional climate change through land use changes. But there is zero evidence verifying that CO2 causes any changes in global temperatures. Could possibly be the case, but there is no supporting, testable evidence. There is only conjecture.
Since a few percent changes in cloud cover overwhelm any possible human effects on atmospheric gas mixtures, the model is worthless from the get-go. Svensmark’s observations, and many others, change the whole ball game.
As another example of the gaping holes in the holey AGW assumption barge, Dr. Jinan Cao posts a link to a new paper, Role of heat reservation of N2 and O2 and the role of heat dissipation of CO2 and water vapour challenging the rejection of low sensitivities. In fact, he observes that since only radiative gases (H2O and CO2, prominently) can dump heat into space, their net effect on heat retention must be negative, not positive.
And so on.