WUWT provided a primer on cloud feedbacks on June 12th, 2009, followed by Willis Eschenbach’s “thermostat hypothesis” also recently published. This new paper by Spencer and Braswell is in the same theme as these.
On the diagnosis of radiative feedback in the presence of unknown radiative forcing
Roy W. Spencer and William D. Braswell
Received 12 October 2009; revised 29 March 2010; accepted 12 April 2010; published 24 August 2010.
Abstract: The impact of time‐varying radiative forcing on the diagnosis of radiative feedback from satellite observations of the Earth is explored. Phase space plots of variations in global average temperature versus radiative flux reveal linear striations and spiral patterns in both satellite measurements and in output from coupled climate models. A simple forcingfeedback model is used to demonstrate that the linear striations represent radiative feedback upon nonradiatively forced temperature variations, while the spiral patterns are the result of time‐varying radiative forcing generated internal to the climate system. Only in the idealized special case of instantaneous and then constant radiative forcing, a situation that probably never occurs either naturally or anthropogenically, can feedback be observed in the presence of unknown radiative forcing. This is true whether the unknown radiative forcing is generated internal or external to the climate system. In the general case, a mixture of both unknown radiative and nonradiative forcings can be expected, and the challenge for feedback diagnosis is to extract the signal of feedback upon nonradiatively forced temperature change in the presence of the noise generated by unknown time‐varying radiative forcing. These results underscore the need for more accurate methods of diagnosing feedback from satellite data and for quantitatively relating those feedbacks to long‐term climate sensitivity.
Citation: Spencer, R. W., and W. D. Braswell (2010), On the diagnosis of radiative feedback in the presence of unknown radiative forcing, J. Geophys. Res., 115, D16109, doi:10.1029/2009JD013371.
Our JGR Paper on Feedbacks is Published
by Roy W. Spencer, Ph. D.
After years of re-submissions and re-writes — always to accommodate a single hostile reviewer — our latest paper on feedbacks has finally been published by Journal of Geophysical Research (JGR).
Entitled “On the Diagnosis of Feedback in the Presence of Unknown Radiative Forcing“, this paper puts meat on the central claim of my most recent book: that climate researchers have mixed up cause and effect when observing cloud and temperature changes. As a result, the climate system has given the illusion of positive cloud feedback.
Positive cloud feedback amplifies global warming in all the climate models now used by the IPCC to forecast global warming. But if cloud feedback is sufficiently negative, then manmade global warming becomes a non-issue.
While the paper does not actually use the words “cause” or “effect”, this accurately describes the basic issue, and is how I talk about the issue in the book. I wrote the book because I found that non-specialists understood cause-versus-effect better than the climate experts did!
This paper supersedes our previous Journal of Climate paper, entitled “Potential Biases in Feedback Diagnosis from Observational Data: A Simple Model Demonstration“, which I now believe did not adequately demonstrate the existence of a problem in diagnosing feedbacks in the climate system.
The new article shows much more evidence to support the case: from satellite data, a simple climate model, and from the IPCC AR4 climate models themselves.
Back to the Basics
Interestingly, in order to convince the reviewers of what I was claiming, I had to go back to the very basics of forcing versus feedback to illustrate the mistakes researchers have perpetuated when trying to describe how one can supposedly measure feedbacks in observational data.
Researchers traditionally invoke the hypothetical case of an instantaneous doubling of the CO2 concentration of the atmosphere (2XCO2). That doubling then causes warming, and the warming then causes radiative feedback which acts to either reducing the warming (negative feedback) or amplify the warming (positive feedback). With this hypothetical, idealized 2XCO2 case you can compare the time histories of the resulting warming to the resulting changes in the Earth’s radiative budget, and you can indeed extract an accurate estimate of the feedback.
The trouble is that this hypothetical case has nothing to do with the real world, and can totally mislead us when trying to diagnose feedbacks in the real climate system. This is the first thing we demonstrate in the new paper. In the real world, there are always changes in cloud cover (albedo) occurring, which is a forcing. And that “internal radiative forcing” (our term) is what gives the illusion of positive feedback. In fact, feedback in response to internal radiative forcing cannot even be measured. It is drowned out by the forcing itself.
Feedback in the Real World
As we show in the new paper, the only clear signal of feedback we ever find in the global average satellite data is strongly negative, around 6 Watts per sq. meter per degree C. If this was the feedback operating on the long-term warming from increasing CO2, it would result in only 0.6 deg. C of warming from 2XCO2. (Since we have already experienced this level of warming, it raises the issue of whether some portion — maybe even a majority — of past warming is from natural, rather than anthropogenic, causes.)
Unfortunately, there is no way I have found to demonstrate that this strongly negative feedback is actually occurring on the long time scales involved in anthropogenic global warming. At this point, I think that belief in the high climate sensitivity (positive feedbacks) in the current crop of climate models is a matter of faith, not unbiased science. The models are infinitely adjustable, and modelers stop adjusting when they get model behavior that reinforces their pre-conceived notions.
They aren’t necessarily wrong — just not very thorough in terms of exploring alternative hypotheses. Or maybe they have explored those, and just don’t want to show the rest of the world the results.
Our next paper will do a direct apples-to-apples comparison between the satellite-based feedbacks and the IPCC model-diagnosed feedbacks from year-to-year climate variability. Preliminary indications are that the satellite results are outside the envelope of all the IPCC models.
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Congratulations, Dr. Spencer, on getting this important paper published. I salute you for your persistence in the face of hostile reviews. Thanks for your synopsis. Its a shame science articles tend not to be written in clear English – in this case I suspect subtlety in the face of hostile politics, as much as professional jargon, necessitates this.
Don´t you think “they”are in urgent need of a “feedback”, a direct hit on the plexus would work? 🙂
Finally we just might be getting back on the road we were so viciously torn from by the greenniks. Decades ago, papers about natural weather and climate events were common. And useful. Then we got on this utterly nonsensical anthropogenic road to hell. I think this paper is every bit as important as Mann-debunking papers and deserves to be top of the heap. It is model debunking. Hugely.
“At this point, I think that belief in the high climate sensitivity (positive feedbacks) in the current crop of climate models is a matter of faith, not unbiased science. The models are infinitely adjustable, and modelers stop adjusting when they get model behavior that reinforces their pre-conceived notions.
“They aren’t necessarily wrong — just not very thorough in terms of exploring alternative hypotheses. Or maybe they have explored those, and just don’t want to show the rest of the world the results.”
Thanks Dr Roy, I hope politicians are reading this.
Dr. Spencer, in reading your book, I was struck by your use of a simple model to demonstrate the top-level, emergent behavior of a complex system. This has similarities to a study I’ve been working on.
The GCM climate models, and many other modeling regimes, try to model all the minutia of a complex system, trying to get each sub-system just right, getting the interactions between all the subsystems right, getting all the initial conditions and forcing functions right, etc. The unspoken assumption is that if one can just get all the subsystems right, the model will mimic the emergent behavior of the real system. The problem is that in practical terms, you can never get all the processes, all the initial conditions, or all the interactions exactly right, and the model fails in unexpected ways. There always seems to be just this one little detail to fix, and it will be right. And, of course, each little detail is harder and more expensive to fix, and needs another order of magnitude of compute power to do it right. The cycle never ends, and in the end, you have a hugely complex, insanely compute-intensive program that will be right if you can just get the funding to fix this one last detail. And it really doesn’t perform any better than the simple simulation you started with. Through the process, you tend to learn a lot about modeling, but not so much about the process you were actually trying to study.
I certainly hope this work gets the attention it deserves.
Dr. Roy W. Spencer’s “The Great Global Warming Blunder” is an instant classic of science and scientific method. The book is crystal clear on first reading and makes an over-powering case for Spencer’s main argument. My second and third readings of the book were undertaken for the joy of watching his elegant argument unfold in all its lovely details. The new paper sharpens his main hypothesis and offers a more systematic treatment of the evidence for it. Dr. Spencer’s book should become a standard in science and philosophy classrooms where scientific method is alive and well.
Hugely, Pamela? I love the word “hugely”.
Thank you for your valuable contribution Dr Roy! I’m still trying to encourage discussion elsewhere as to why an experiment undertaken within an enclosed (and ‘dry’) environment gives positive feedback results, when observation of Earth’s atmosphere gives neither positive, or negative, feedback (Miskolczi)! I’m sure there are unrecognised attractors at work here.
I wish you all the best.
Best regards, Ray Dart.
Congratulations to Roy Spencer and William D. Braswell!
This question occurs to me: where are the works validating positive feedback?
I was waiting for this to finally happen. I tip my hat to you Dr. Spencer, your persistence is an example to all. Congratulations.
Dear Doctors,
As others have said: Congratulations!
I must spend some time digesting that paper.
Aside from that, you mention models, and as many of the rest of us have come to understand, models aren’t worth much save to understand a brief glimpse of ‘what’s happening now.’
It is for that reason that most –if not all– climate models are essentially worthless and broken beyond repair: You can’t know the future, so you can’t predict it with any degree of accuracy, unless you’ve manipulated the past –and the present– sufficient to know the likely outcome …
It is my considered opinion that what most modelers don’t comprehend –or refuse to internalize– is that because of the changing nature of the beast they attempt to model, they can never begin to produce anything considered remotely accurate 100% of the time.
Tomorrow isn’t yesterday. Tomorrow, something big in the cosmic nature of things might happen and upturn the apple cart. What then?
And, as we both know: NOTHING remains static for very long. The modelers KNOW such, and are playing the unknowing like a cheap banjo. They contend that the Earth’s climate system is supposed to remain static, and that humans are upsetting that condition.
Perhaps if we were to know the future with a fair degree of certainty –a thing I doubt will ever happen– then we’d be able to surmise a modicum of prescience, and forecast future weather events. But that’s entirely wishful thinking.
It is because of the variability of the beast and its thoroughly unpredictable behavior, that attempts at modeling are essentially academic endeavors only.
I wonder: Are those ‘cheap banjoes’ starting to pay attention?
Once again: Congratulations on being published!
“The models are infinitely adjustable, and modelers stop adjusting when they get model behavior that reinforces their pre-conceived notions.”
Which means they are not models, they are fits. The whole point of models is they should be ‘predictive’ in some manner, they should inform you about some part of the system you were unaware of, if they do not, then you are better off with a polynomial.
“Interestingly, in order to convince the reviewers of what I was claiming”
Dr. Spencer, what you guys had to do was prove to them that they were wrong,
and that took years….
Thank you!
spangled drongo says:
August 28, 2010 at 5:18 pm
“Thanks Dr Roy, I hope politicians are reading this.”
Yep. Some of us.
> I found that non-specialists understood cause-versus-effect better than the climate experts did!
I wrote Science, Method, Climatology, and Forgetting the Basics in part because some scientists seem to have forgotten the Scientific Method.
Perhaps your climate experts need a little positive feedback themselves. Oh, that’s right, their system has attenuators, it’ll take a lot of positive feedback….
I’ll go ask at http://www.drroyspencer.com if he can release the dialog in the peer review process like Leif did at http://wattsupwiththat.com/2010/05/29/leif-svalgaard-on-the-experience-of-peer-review/
Dr Spencer,
I be curious to see the list of objections to earlier drafts.
Loved the book, Dr Spencer, and I am sure I shall find the article fascinating, although much may go over my head.
I would also be very interested to see the history of the single hostile reviewer, should you feel able to release this information (and I fully understand if you are either unable or unwilling).
I also agree with Amino Acids: “This question occurs to me: where are the works validating positive feedback?”
Roy Spencer & William Braswell: Kudos.
Hello, Roy.
I see that you are concentrating specifically on non radiative forcing that is internal to the climate system.
However radiative forcing from above and which is external to the system (solar) must always ‘prime’ the system in which those non radiative forcings then arise.
I have been trying to create a complete climate description that integrates variability from above (solar) with variability from below (oceanic) and I don’t think we can accommodate all climate observations without invoking both.
Leif Svalgaard takes the view that all climate changes are internally generated from ‘bottom up’ but many including myself see scope for a longer term slow cycling from solar variability above on a ‘top down’ basis.
Does your work provide any guidance as to how variations in external radiative forcings might affect those non radiative internal forcings ?
I see the oceans as being the location where the former is converted to the latter over time and the air circulation systems (latitudinal positioning) with the hydrological cycle (variations in speed or intensity and including cloudiness and albedo) always operating to neutralise any divergence between the external radiative (from above) and internal non radiative (from below) processes so as to provide a strongly negative response to either type of forcing in either direction (warming or cooling).
In particular, if solar variability were to have differential warming or cooling effects on the separate layers of the atmosphere then solar variability could alter the temperature of the stratosphere by changing the upward energy flux and thus affect the pressure distribution (and so change cloudiness and albedo) below the tropopause. That would be an example of a radiative external forcing becoming disguised as an internal and negative non radiative forcing.
Would that wider overview fit with your findings concerning internal non radiative processes ?
First Class example of following the scientific method through to its logical conclusions. Thank you for your collective efforts and for demonstrating how solid science is supposed to be done.
Congratulations, Drs. Spencer and Braswell! Your persistence has finally paid off.
Now put on your helmets and take to the trenches. Incoming!
I’m forwarding to my Congress critter’s aide, smart kid, I’ve been educating him on AGW
and assorted myths. Seems to be working and his boss is smart too..
Thanks, Dr. Spencer…
Dr Spencer:
What does Lindzen say about this paper?
Good work gentlemen!!!
Another excellent paper from Dr. Spencer, added it to the ever growing list,
800 Peer-Reviewed Papers Supporting Skepticism of “Man-Made” Global Warming (AGW) Alarm