January 14, 2009 | New research by NCAR scientists Clara Deser, Robert Tomas, and David Lawrence uses atmospheric general circulation model experiments to explore how projected losses in Arctic sea ice may affect climate. The goal of the study is to isolate the direct impacts of Arctic sea ice loss without feedbacks from other components of the climate system, notably the oceans. Scientists in the United Kingdom and Norway have undertaken similar efforts, but the CGD study is the first to apply a high-resolution, integrated model to this research question.

The team ran two experiments with the Community Atmospheric Model Version 3 coupled to the Community Land Model, comparing results for the control period of 1980-1999 to projections for 2080-2099. Among the most significant findings is the model’s prediction that loss of Arctic sea ice will result in considerable (more than 5°C) warming over adjacent land regions north of 65° latitude, particularly during autumn and winter. The model also predicts increased snowfall over land, especially over Siberia and northern Canada, as ice loss sends moisture from the ocean into the atmosphere.

Another important finding is that although sea ice loss peaks in September, the model shows that the atmosphere’s full response is delayed until November or December. “This is because the ocean is more efficient at losing heat to the atmosphere in winter when air temperatures are lowest and winds strongest,” Clara explains.

Clara hopes that other modeling groups will run similar experiments with different atmospheric general circulation models to compare results. The next step for the CGD group is to incorporate an interactive ocean component into its atmospheric model to study how ocean temperatures, salinity, and currents respond to sea ice loss. This new version of the model will be used for the next IPCC report.

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