Re: Global Cooling on it's way
Posted by Dale on Jan 18, 2002 at 11:56
Re: Global Cooling on it's way (Natalie L. Smith)
Yes. I am being pragmatic in that I have no clue what the actual details are at the moment but I see the results are that any change in the atmospheric constituents that should produce a large temperature change are being offset by other changes in the atmosphere that counter that change. Over the eons there have had many atmospheric changes that, in a static system, would have caused runaway temperature changes. Yet we have never had a runaway temperature change on earth. Therefore there must be offsetting changes that we are not considering when we predict significant global warming or global cooling due to specific atmospheric changes.
My simplistic example is that excess CO2 causes warming which causes more water vapor which causes more warming except it also causes more cloud formation which causes cooling. In this simple system the cooling effect of cloud formation almost exactly balances the change in CO2 as evidenced by large changes in CO2 produce far smaller changes in temperature than would be expected. The actual situation may be much more complicated but the pragmatic result is that any prediction of large temperature changes from CO2 seem to be proven false by the lack of evidence that previous excursions produced the changes we are predicting today. Our models are trying to make predictions from first principles rather than by observing actual changes and matching previous results. They don't consider enough variables and so they are wrong. A better way would be to work backward from actual changes to find causation and create a model from that. But that would mean that we couldn't declare global warming was going to be a serious problem since we have no data to support it being a problem in the past. If I were doing the modeling I would forget that CO2 and water vapor and methane and... are supposed to cause global warming and I would concentrate on temperature changes that have been seen in the past and try to correlate them to physical changes that are observed in the historical record. Does CO2 cause global warming or does global warming cause a rise in CO2 with all the rotting vegetation that the additional heat produces? Or is it a far more complicated interaction?
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