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Re: [Phys-l] Climate skeptic convinced by data. Was: Re: Mike Mann _The hockey



Whenever debates like this get going among people who presumably CAN be persuaded by evidence and rational argument, I like to haul out a simple summary provided by Art Hobson a couple of years ago. I have yet to hear anything approaching a compelling response. Maybe this time will be different.

"The sudden atmospheric CO2 spike during only the past two centuries is unprecedented in at least 800,000 years of alternating ice ages and interglacials. This spike is of undeniably human origin; so far as I know, even climate skeptics agree with this statement. The natural greenhouse effect undeniably warms Earth’s surface by 33 degrees C, and CO2 is known to be the second strongest greenhouse gas, after water vapor. There’s every reason to think that this CO2 spike is responsible for the temperature increase, and indeed nobody has proposed a plausible alternative mechanism. Common sense, simple models, and all of the computer models predict that the CO2 spike should cause a few-degree increase in the greenhouse effect. That’s exactly what’s been happening. Indeed, climate skeptics need to answer the obvious question: Why wouldn’t you expect that high CO2 levels are causing high temperatures?"

--Art Hobson, The Physics Teacher, Vol. 48, pp 502-503, November 2010

John Mallinckrodt
Cal Poly Pomona