Tuesday, May 3, 2011

Hansen by logarithm

As I have been unable to find the linear graphs that I thought Hansen was using, I have recreated his numbers using the logarithmic model I described previously. After some fiddling around with the parameters, I have managed to create a reasonable match with observed temperatures and the observed rate of warming over the last 40 years using a climate sensitivity of 3.3 degrees per doubling. I homed in on this number because of a priori knowledge that Hansen's model E matches observations the best when such a sensitivity is used, so this is not an independent test.

I should again point out here that lower sensitivities require a faster response time and higher sensitivities require a lower response time.

My model predicts a rate of warming of .0187 degrees per year for the next 25 years, which equates to a bit less than half a degree of warming. At that point, we would be committed to a further one degree of warming, most of which would occur this century. If all human greenhouse gas emissions ceased at that point, total warming from preindustrial would be around 2.3 degrees by the time warming ceased.

I will be interested to see how my model compares with reality over the next little while.

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