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  • Crucifix, M., 2006: Does the LGM constrain climate sensitivity ?. Geoph. Res. Lett., 33, L18701, 10.1029/2006GL027137.

Four simulations with atmosphere-ocean climate models have been produced using identical Last Glacial Maximum ice sheets, topography and greenhouse gas concentrations. Compared to the pre-industrial, the diagnosed radiative feedback parameter ranges between $-1.30$ and $-1.18 \mathrm{Wm^{-2}K^{-1}}$, the tropical ocean sea-surface temperature decreases between $1.7$ and $2.7$ $^\circ$ C, and Antarctic surface air temperature decreases by 7 to 11 C. These values are all compatible with observational estimates, except for a tendency to underestimate the tropical ocean cooling.
On the other hand, the same models have a climate sensitivity to CO$_2$ concentration doubling ranging between 2.1 and 3.9 K
It is therefore inappropriate to simply scale an observational estimate of LGM temperature to predict climate sensitivity.
This is mainly a consequence of the non-linear character of the cloud (mainly shortwave) feedback at low latitudes. Changes in albedo and cloud cover at mid and high latitudes are also important, but less so.}


Last Updated: 2007-07-26

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