"Climate models are tuned, climate models are fudged Perhaps it is because of the complexity, or perhaps because of our relative lack of knowledge of the climate system, but when climate models are put together they rarely perform in a realistic manner, with too much or too little heat being retained by the virtual atmosphere. This results in the virtual temperatures rapidly drifting away from the observed ones. In order to address this problem, climate models are ‘tuned‘ – in other words some of the parameterisations are arbitrarily adjusted – so as to make the model warm at a more realistic rate. An example would be to adjust the way clouds are represented in the model. Clouds are one of the great areas of uncertainty in the climate system, so many of the possible parameterisations are plausible. Different combinations of input values could give a virtual global temperature record similar to the real one, but completely different estimates of future warming. Which climate future is the real one is, again, anyone’s guess, and is therefore possible to simply pick the one that gives a desired answer."
If the computer model predicts an event before it happens, what then?
ReplyDeleteI am not aware of a computer climate model ever having predicted an event before it happens, but I am aware of them predicting events which have not happened, such as the existence of a "hotspot" in the troposphere above the tropics.
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