The role of sea ice in 2 × CO2 climate model sensitivity. Part I: the total influence of sea ice thickness and extent

Abstract

As a first step in investigating the effects of sea ice changes on the climate sensitivity to doubled atmospheric CO2, the authors use a standard simple sea ice model while varying the sea ice distributions and thicknesses in the control run. Thinner ice amplifies the atmospheric temperature sensitivity in these experiments by about 15% (to a warming of 4.8°C), because it is easier for the thinner ice to be removed as the climate warms. An experiment with sea ice not allowed to change between the control and doubled CO2 simulations illustrates that the total effect of sea ice on surface air temperature changes, amounts to 37% of the temperature sensitivity to the CO2 doubling, accounting for 1.56°C of the 4.17°C global warming. -from Authors