Positive feedback in the global climate

[GregLocock]

There undoubtedly are positive feedbacks, for example, if the temperature rises high albedo ice melts and is replaced by low albedo seawater. There are undoubtedly negative feedbacks, such as the 2 o'clock formation of clouds over the tropics. But to get from the laboratory air column result of 1 deg C/doubling CO2 to the silly sorts of numbers the climate models predict (1.5-6 I think is the latest range the IPCC is confident in), you need a lot more positive feedback than negative.

But as you well know, a system with positive feedback is unstable.

Yet according to the hockey stick graph the period 1000-1800 is remarkably flat. But any perturbation would, in the presence of positive feedback, send the temperature off on a one way direction rise or fall ad infinitum.

My guess is that there are many positive and feedback loops, operating at different gains and with different time constants.

Cheers

Greg Locock


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[rb1957]

My guess is that the "hockey stick" is an artifact of the statistical model.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.