Does Nature’s Thermostat Exist? A Global Warming Debate Challenge

January 13th, 2009 by Roy W. Spencer, Ph. D.

Scientific disagreements over just how much mankind’s carbon dioxide emissions will warm the planet can be described with the analogy of the thermostat in your home. You set the thermostat to a certain temperature, and if it senses (for example) that the temperature is rising too much above that preset level, a cooling mechanism (air conditioning) kicks in and works to push the temperature back down.

I, and a number of other scientists, believe that nature has a thermostatic control mechanism that “pushes back” against a warming influence, such as the relatively weak warming from more atmospheric carbon dioxide. (The direct warming effect of more CO2 would amount to little more than 1 deg. F by late in this century, and is generally not the subject of debate.)

In climate research (and engineering, and physics) a thermostatic control mechanism is called ‘negative feedback’, and as discussed elsewhere on my web site there are a number of studies that suggest it really does exist in the climate system. At this point my own research suggests that the natural cooling mechanism is most likely due to the response of clouds to warming. While it is a bit technical, the issue is introduced in this peer-reviewed publication.

To be sure, positive feedbacks also exist in nature, such as the enhanced solar heating of the ocean that accompanies the melting of sea ice. But these are regional and relatively weak compared to the dominating, global influence of cloud feedbacks.

The reason why we keep hearing about how serious global warming will be is that all twenty-something of the computer climate models tracked by the IPCC now have net positive feedbacks. They enhance the small direct warming effect of extra CO2…by near-catastrophic amounts for a couple of the models.

Of course, the models are only behaving the way they are programmed to behave, and here I discuss why I think the modelers have seriously misinterpreted the role of clouds in climate change when building those models. While the modelers do not realize it, their tests of the models’ behavior with satellite observations have not been specific enough to validate the models’ feedback behavior. In effect, their tests are yielding ‘false positives’.

Obviously, the thermostat (feedback) issue is the most critical one that determines whether manmade global warming will be catastrophic or benign. In this context, it is critical for the public and politicians to understand that the vast majority of climate researchers do not work on feedbacks.

In popular political parlance, most climate researchers do not appreciate the nuanced details of how one estimates feedbacks in nature, and therefore they are not qualified to pass judgment on this issue. Therefore, any claims about how many thousands of scientists agree with the IPCC’s official position on global warming are meaningless.

I would challenge any IPCC scientist who considers himself or herself an expert on feedbacks to debate this issue against me. We can invite a variety of physicists and engineers who understand the concept of ‘feedback’, and who do not already have strong philosophical or political biases on the issue, and ask them to judge whether the IPCC models are behaving in realistic ways when it comes to cloud feedbacks.

The debate could be in either oral or written form, with our best arguments presented for evaluation by others. Then, those judges can summarize in lay terms for politicians whether “the science is settled” on this issue.

And I’m particularly interested to see whether anyone can respond to this challenge without using phrases like “this issue is settled”, “the cloud claim is bogus”, or without ad hominem attacks.

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