Yesterday we talked about the new paper from Nic Lewis, now Troy Masters has a new paper in press at Climate Dynamics here.
Observational estimate of climate sensitivity from changes in the rate of ocean heat uptake and comparison to CMIP5 models
Unfortunately, Springerlink wants $39.95 for the privilege of reading it, so all I can do is to provide the abstract. From his blog however, Troy does show figure 5 of the paper:
Abstract. Climate sensitivity is estimated based on 0–2,000 m ocean heat content and surface temperature observations from the second half of the 20th century and first decade of the 21st century, using a simple energy balance model and the change in the rate of ocean heat uptake to determine the radiative restoration strength over this time period. The relationship between this 30–50 year radiative restoration strength and longer term effective sensitivity is investigated using an ensemble of 32 model configurations from the Coupled Model Intercomparison Project phase 5 (CMIP5), suggesting a strong correlation between the two. The mean radiative restoration strength over this period for the CMIP5 members examined is 1.16 Wm−2K−1, compared to 2.05 Wm−2K−1from the observations. This suggests that temperature in these CMIP5 models may be too sensitive to perturbations in radiative forcing, although this depends on the actual magnitude of the anthropogenic aerosol forcing in the modern period. The potential change in the radiative restoration strength over longer timescales is also considered, resulting in a likely (67 %) range of 1.5–2.9 K for equilibrium climate sensitivity, and a 90 % confidence interval of 1.2–5.1 K.
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Compared to Dr. Roy Spencer’s post about models -vs- reality…
…it looks more and more as if climate sensitivity is on the lower end of the scale, rather than the high end such as was claimed recently at RealClimate by Fasullo and Trenberth which was 4°C for a doubling of CO2.
And there’s yet ANOTHER paper arguing for lower climate sensitivity. See it here
Causes of the global warming observed from the 19th century
M.J. Ring, D. Lindner, E.F. Cross, R.E. Schlesinger
Abstract. Measurements show that the Earth’s global-average near-surface temperature has increased by about 0.8℃ since the 19th century. It is critically important to determine whether this global warming is due to natural causes, as contended by climate contrarians, or by human activities, as argued by the Intergovernmental Panel on Climate Change. This study updates our earlier calculations which showed that the observed global warming was predominantly human-caused. Two independent methods are used to analyze the temperature measurements: Singular Spectrum Analysis and Climate Model Simulation. The concurrence of the results of the two methods, each using 13 additional years of temperature measurements from 1998 through 2010, shows that it is humanity, not nature, that has increased the Earth’s global temperature since the 19th century. Humanity is also responsible for the most recent period of warming from 1976 to 2010. Internal climate variability is primarily responsible for the early 20th century warming from 1904 to 1944 and the subsequent cooling from 1944 to 1976. It is also found that the equilibrium climate sensitivity is on the low side of the range given in the IPCC Fourth Assessment Report.
From the paper:
Additionally, our estimates of climate sensitivity using our SCM and the four instrumental temperature records range from about 1.5 ̊C to 2.0 ̊C. These are on the low end of the estimates in the IPCC’s Fourth Assessment Report. So, while we find that most of the observed warming is due to human emissions of LLGHGs, future warming based on these estimations will grow more slowly compared to that under the IPCC’s “likely” range of climate sensitivity, from 2.0 ̊C to 4.5 ̊C. This makes it more likely that mitigation of human emissions will be able to hold the global temperature increase since pre-industrial time below 2 ̊C, as agreed by the Conference of the Parties of the United Nations Framework Convention on Climate Change in Cancun.
Dr. Judith Curry sums it up pretty well:
In weighing the new evidence, especially improvements in the methodology of sensitivity analysis, it is becoming increasing difficult not to downgrade the estimates of climate sensitivity.
All this blows the laughable Skeptical Science claim Climate Sensitivity Single Study Syndrome, Nic Lewis Edition out of the water. Dana should quit while he’s ahead, because his arguments aren’t convincing.
h/t to Mosher
Related articles
- A Comparison Of The Earth’s Climate Sensitivity To Changes In The Nature Of The Initial Forcing (wattsupwiththat.com)
To joeldshore:
And I recommend that you grow a sense of humor.
Chris R:
A joke is laughed at by those who have a sense of humor. It cannot have a sense of humor.
Richard
To richardscourtney, also joeldshore:
Richard:
Thank you. I should remember that there are those who can
be ribbed, and those who cannot. It seems that
joeldshore is among those who cannot.
Joel:
I should have made clear to you that I did, in fact, read your comment
in its entirety. I also read the reviewer comment you linked.
“Anonymous reviewer number 2” never said that Bjornbom
“…made no attempt to validate” his method. The reviewer
said that the discussion of the interpretation of results was
unclear. Not the same thing. Beyond that, when the reviewer
says, in his first paragraph, that this result is ” …
politically controversial…” I automatically begin applying a
50% discount to what follows.
I suppose I shouldn’t have gone for a cheap laugh, but the fact
that even with your correction applied, the result was still
50% smaller than the lowest IPCC estimate seemed to
me to be quite amusing.
Here, I will help you out for free! … the real climate “sensitivity” to CO2 is exactly, and precisely, ZERO degrees C or F. Nadda, nothing, zilch! There is no “sensitivity”. That is complete garbage!
Paywalled? He does state:
” It is pay-walled, but please contact me if you need a copy and do not have University access. Anyhow, a zip that includes all my code and data is available here.”
So it sounds like he is willing to share it with people that take the trouble to contact him directly. His data is freely available too.
I don’t have the time to review it, however I don’t feel the comment “Unfortunately, Springerlink wants $39.95 for the privilege of reading it, so all I can do is to provide the abstract.” is entirely appropriate – perhaps he has perfectly legitimate reasons for paywalling it that he didn’t mention.
Appreciate reading about this article, wish I had more time to follow along…
Chris R. says:
From the reviewer’s comments:
I said: “..the author of the paper has made no attempt to validate his method of computing the feedback parameter. Hence, this is a result using a method that is completely untested. You just have to take it on faith that this is a valid method for assessing the feedback parameter and climate sensitivity.” How is this an unreasonable characterization of the information that the reviewer provided?
What was more amusing was the fact that somebody (Douglas Hoyt) who presumably characterizes himself as a skeptic uncritically accepted a HockeySchtick’s gross (factor of 4) mischaracterization of the paper’s result…and also uncritically accepted the paper’s result itself despite the fact that the method has not been validated as giving “any insight to the value of long global sensitivity to increases in greenhouse gases in models, let alone the real world”.
ferd berple says:
Your entire comment is based on a misunderstanding of what “positive feedback” means in the context of these climate discussions. You might want to read up on what Troy Masters (a skeptic, or at least a lukewarmer) has to say about it here: http://troyca.wordpress.com/radiation-budget-and-climate-sensitivity/ in particular, note this part:
In other words, when climate scientists says that the net feedback is positive, they mean the net feedback not including the Planck response.
@ur momisugly jnpics, re: 4//18/13, 7:19 AM
When I saw that your fervently sincere post (which started out fine but ended up sounding like a hysterical piglet) got all those “thumbs down!”, my heart went out to you. Every time I’ve tried to show an Envirocult member the truth, I end up nearly running down the road hollering my head off in much the same way. I think the following edited version captures the essence of your comment:
Man made Global warming is a hoax. I am totally frustrated with this. It is a political problem. Thanks is due to this site for proving the “climate models” false along with everything else the IPCC has said. [jnpics abridged]
Try re-posting that. No thumbs up, perhaps (and who gives a rat’s micrometer anyway!), but, at least you can redeem your reputation for rationality. Keep on posting!
Janice Moore:
In your fine post at April 18, 2013 at 8:56 pm kindly addressed to jnpics you say
Try re-posting that. No thumbs up, perhaps (and who gives a rat’s micrometer anyway!),
I am at a loss to understand why these ‘thumbs’ have been added to WUWT.
They slow down and corrupt links to posts, they discourage debate, they prejudice opinions of posts by readers who see a ‘log’ of recorded opinions, and as you point out they can discourage new and inexperienced contributors from making future posts. Indeed, a person thinking of making a post for the first time may be dissuaded by seeing the ‘thumbs’ obtained by jnpics.
Simply, the ‘thumbs’ seem to act against the nature of WUWT which has made it the Best Science Blog on the web.
Trolls attempting to disrupt threads need to be dissuaded. New posters need to be encouraged and not dissuaded because with experience they may become very useful contributors.
As your kind post to jnpics implies, the ‘thumbs’ may have inhibited debate on this thread, and I add that I suspect this is probably not the only thread to have been similarly affected.
Richard
If the climate models were truly concerned with calculating CO2 sensitivity, then CO2 sensitivity would be one of the outputs of the models. The models would use observed temperature as an input and spit out climate sensitivity as an output.
Well said! Or at least, they would optimize hindcast/training/trial set performance in a predictive model on its value or — oops — do a rather difficult multivariate performance optimization on an entire vector of presumed inputs, along with a meta-sensitivity analysis of the statistical sort that integrates covariant regimes with roughly equal predictivity that determine (sadly broad, multidimensional ellipsoidal at best) ranges for those parameters all of which yields roughly equivalent hindcast/trial set performance once the model is built using a training set.
One seriously wonders if any of the climate modelers really understand predictive modeling theory in the abstract at all. I do this sort of thing for money — you don’t get the opportunity to fail to handle input degeneracy, input covariance, overtraining, and so on twice when people pay you for it and you screw up. This is actually a stronger criterion than “peer review”, where all too often the only money on the table comes from not pissing off the powers that regulate the flow of grant money or (biased) reviewers who have their own dog in the race.
The point being that one ultimately has to concentrate on models that are robustly predictive on trial data after being built on training data (at the expense of model detail as needed) and even then, forward prediction is fraught with peril in a chaotic system. Spencer’s lovely diagram above is a perfectly wonderful example of why.
Since everybody on this list loves numerology, here’s an interesting bit of it. Plot the estimates of climate sensitivity over time. Hmm, a monotonic decreasing function (with an artificially tightening range, since literally nobody dares to publish a result where the error estimate includes zero — they’d have hockey team career-assassins on their trail overnight, so the ranges are carefully asymmetric and skewed on the warm side instead of being nice and Gaussian above, to which I can only reply “hah, bah!”).
Is it converging low? No sign of it yet. How can there be? Nobody has the guts to drop it to where the actual data record in Spencer’s graph above is at the centroid of the model — they persist in building models where the bottom of the range can reach it instead, assuming utterly without justification that the current climate isn’t “what it should be” but is lowball noise. Maximum entropy? Maximum likelihood? Bayes with uniform priors optimized to the actual data? Ability to hindcast any trial set outside of some carefully limited range that (for example) carefully excludes the LIA and/or MWP or the rest of the Holocene? Hell no. Just build a model with (in the end) a simple one-parameter dominant behavior that works only for trial sets selected from the last century where the data was largely monotonic (regardless of how many parameters contributed to it) and tune the parameters so that they BARELY contain the current observations while preserving the illusion of understanding and one’s grant stream.
Hah. Bah.
I can’t really complain, though. More and more climate scientists are having the courage to break ranks, and eventually we will have enough, good enough data and honest enough analysis that we will start to actually work out some ROBUST ranges for things, and perhaps in a few decades have a vastly improved idea of how the climate actually works. Perhaps after the climate has worked through a few more solar cycles and the NAO finally changes phase, perhaps after ENSO finishes surprising us.
One day perhaps I’ll have the time and energy to do a top post on chaotic oscillation and the danger of single-parameter numerology. You’d think climate scientists had never heard of a Poincare cycle, a Van der Pol nonlinear oscillator:
http://en.wikipedia.org/wiki/Van_der_Pol_oscillator
or any of the rest of this. The Van der Pol oscillator is simple compared to the climate. For one thing, its driver is hardly a clean sinusoid, it is itself a chaotic noisy function. For another, its nonlinear feedback terms have multiple signs. For a third, the fact that global temperature does follow Hurst-Kolmogorov patterns of stability followed by rapid jumps suggests that the global climate cycle is best described by a phase space of multiple attractors with many locally stable orbits where the system jumps between attractors on a decadal timescale with century-scale factors that continuously change the local phase space potential surfaces upon which the state orbits.
rgb
Dear Mr. Courtney,
I gave your comment complimenting mine a thumbs up. Heh, heh. Thank you for your affirmation and, yes, I agree. While the thumbs up is a nice way to say “atta boy” or “atta girl,” the collateral damage from the thumbs down with its implication that not only should this post disappear but you should, too, it not worth it. I’m not too sure about jnpics… . I think she or he gave me a thumbs down. (:|}
Other posters have unfavorably compared the new rating system to Facebook. I think similarly. The main reason I have not joined Facebook is for that nauseating faux popularity element. Oh, certainly, if one is “big” enough, one will overlook and not “give a rat’s squeek” about it, but, we are, all of us, “pervious, through a chink or two”. Indeed, WUWT, where respect and focus on facts prevails, is “the Best Science Blog on the web.”
As I’ve pointed out many times in the past, there is no such thing as an equilbrium climate sensitivity for is is defined in terms of an equilibrium temperature but it is not an observable.