Offered FYI in response to a recent post.

Freeman admitted he was a skeptic on global warming. His problem was not change in the climate. “In the long view we ARE changing the climate.” He felt that climate was hugely complex, that we understand very little of it and many people are reducing this unknown complexity into one data point — the average temperature somewhere. Until we understand what kind of changes we are making in our “solutions” he says he believes the best action on global climate change right now is inaction.

But I have studied their climate models and know what they can do. The models solve the equations of fluid dynamics and do a very good job of describing the fluid motions of the atmosphere and the oceans. They do a very poor job of describing the clouds, the dust, the chemistry and the biology of fields, farms and forests. They do not begin to describe the real world that we live in.

The real world is muddy and messy and full of things that we do not yet understand. It is much easier for a scientist to sit in an air-conditioned building and run computer models than to put on winter clothes and measure what is really happening outside in the swamps and the clouds. That's why the climate model experts end up believing their own models.

Besides the general prevalence of fudge-factors, the latest and biggest climate models have other defects that make them unreliable. With one exception, they do not predict the existence of El Niño. Since El Niño is a major feature of the observed climate, any model that fails to predict it is clearly deficient. The bad news does not mean that climate models are worthless. They are, as Manabe said thirty years ago, essential tools for understanding climate. They are not yet adequate tools for predicting climate. If we persevere patiently with observing the real world and improving the models, the time will come when we are able both to understand and to predict. Until then, we must continue to warn the politicians and the public: don't believe the numbers just because they come out of a supercomputer.

Freeman Dyson: I am always happy to be in the minority. Concerning the climate models, I know enough of the details to be sure that they are ... [ Read More (0.5k in body) ]