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The climate response to sudden summertime sea ice loss in a coupled ocean-atmosphere model

Observations have shown that the Arctic sea ice levels been declining over the past few decades, with the biggest changes occurring in the past 5-10 years. Sea ice loss can impact the atmosphere through decreasing the albedo and increasing the heat fluxes into the atmosphere. This causes an increase in temperature in the Arctic and possibly also a change in the atmospheric circulation and precipitation. It can be difficult to determine what these effects are in observations because of other forcings and internal variability, so we use models to isolate the effect that melting sea ice has on climate. Most of these studies simply force an atmospheric model with prescribed sea surface temperatures and lower sea ice concentrations, ignoring changes in the ocean that can occur as a result of the ice loss. I will present results from a sea ice loss experiment using the Community Climate System Model 4 (CCSM4) which is a coupled ocean-atmosphere model. I will show both the equilibrium and the transient responses in the mean climate, as well as how the variability changes as a result of melting the sea ice.