Little Feedback on Climate Feedbacks in the City by the Bay

December 16th, 2009 by Roy W. Spencer, Ph. D.

The Fall meeting of the American Geophysical Union (AGU) here in San Francisco this week is amazing for it’s sheer size: many thousands of Earth scientists presenting talks and posters on just about every Earth science subject imaginable.

Today was my chance to try to convince other scientists who work on the critical issue of feedbacks in the climate system that some fundamental mistakes have been made that have misled climate researchers into believing that the climate system is quite sensitive to our greenhouse gas emissions. A tough sell in only 14 minutes.

It was standing room only…close to 300 scientists by my estimate. There were only a couple of objections to my presentation…rather weak ones. Afterward I had a number of people comment favorably about the ‘different’ way I was looking at the problem.

And while that should be comforting, it is also disturbing. Since when in science did the issue of ‘causation’ become a foreign concept? When did the direction of causation between two correlated variables (in my case, clouds and temperature) become no longer important?

If temperature and clouds vary together in ‘sort of’ the same way in satellite observations as they do in climate models, then the models are considered to be ‘validated’. But my message, which might not have come across as clearly as it should have due to time constraints, was that such agreement does NOT validate the models when it comes to feedback, and feedbacks are what will determine how much of an impact humans have on the climate system.

Andrew Lacis, who works climate modeling with Jim Hansen, came up and said he agreed with me that, in general, the feedback problem is more difficult than people have been assuming. In a talk after mine, Graeme Stephens gave me a backhanded compliment when he agreed with at least my basic message that the way in which we assume the climate system functions (in my terms, what-causes-what to happen) IS important to how we then deduce how sensitive the climate is to such things as our carbon dioxide emissions.

The three organizers of the session were very gracious to invite me, since they knew my views are controversial. One of the three was Andrew Dessler, who works in water vapor feedback. I had never met Andy before, and he’s a super nice guy. They all agreed that there needs to be more debate on the subject.

But most of the talks presented followed the recipe that has become all too common in recent years: analyze the output of climate models that predict substantial global warming, and simply assume the models are somewhere near correct.

There seems to be great reluctance to consider the possibility that these computerized prophets of doom, which have required so many scientists and so much money and so many years to develop, could be wrong. I come along with an extremely simple climate model that explains the behavior of the satellite data in details that are beyond even what has been done with the complex climate models…and then the more complex models are STILL believed because…well…they’re more complex.

Besides, since my simple model would predict very little manmade global warming, it must be wrong. After all, we know that manmade global warming is a huge problem. All of the experts agree on that. Just ask Al Gore and the mainstream news media.

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