The Oil Drum

174 comments on Living in the Eemian

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Stuart Staniford on February 19, 2006 - 9:56pm

My assumption is that the asymmetry you note is a function of albedo feedback off the ice sheets and the fact that it's a lot easier to destroy an ice sheet by having it all slide out to sea than it is to build one (which has to be done one year's snowfall at a time).

On past interglacials - if you go back 400k or so, there was a fairly broad one. There is a debate on at the moment started by Ruddiman as to whether the holocene would have been shorter if it wasn't for low level forcings due to human agricultural development (ie long before the industrial era). He summarizes his arguments in a very nice book called "Plows, plagues, and petroleum". He thinks we would have already have been starting the long slow descent into the next ice age if it wasn't for the invention of agriculture. However, there's certainly no consensus around that idea: others think it's just the way the particular combination of orbital factors line up. There was a good discussion of this recently over at RealClimate.

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Agric on February 20, 2006 - 12:05am

Albedo is an obvious possibility but I would guess another (at least), more rapid, positive feedback process is involved. I know I am speculating now but several possibilities occur to me: thermohaline circulation changes; permafrost thawing; CO2 cycle changes.

Another thought occurs to me: the dramatic large temperature increases may indicate that increased atmospheric cloud due to warming may be less of a negative feedback (albedo) than expected.

Thanks for the link, it will have to wait till tomorrow but I will definitely read it and say what I think here.