Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
The Ice-Albedo Feedback in a Changing Climate: Albedos from Today and Reflections on Tomorrow
Don Perovich1
1Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, NH, 03755, USA, Phone 603-646-4255, Fax 603-646-4644, perovich@crrel.usace.army.mil
The ice-albedo feedback mechanism plays a key role in the heat budget of sea ice and snow in the Arctic. It is a positive feedback that is of great import to climate studies. There has been significant recent progress in defining the key elements of the ice-albedo feedback, in quantifying the feedback, and incorporating improved treatments of the feedback into general circulation models. Recent research has found that the ice-albedo feedback is largely determined by the timing of seasonal transitions, the duration of summer melt, and the evolution of melt ponds. It is typically assumed that a warming climate would mean a longer melt season, with an earlier onset of summer melt and a later freezeup, more ponded sea ice, and a stronger feedback. These changes could be incorporated into the existing theoretical framework in a straightforward way. It is possible, however, that the changes will be revolutionary, rather than evolutionary. There may be a fundamental change in the nature of the sea ice cover that will cause a profound change in the ice-albedo feedback. There are obvious impacts from a warming climate, such as larger amounts of open water resulting in a decrease in albedo and greater heat input to the system. There are also more subtle consequences, such as those due to enhanced amounts of first year ice or changes in winter snow accumulation. The impact of more first year ice on the ice-albedo feedback may depend on the degree of deformation. Deformed first year ice may have morphological properties, and an albedo evolution, similar to multiyear ice. In contrast, undeformed first year ice will have extensive pond coverage, no surface scattering layer, lower albedos, and an accelerated ice-albedo feedback. Deeper snow on the sea ice would reduce surface melt early in summer, but would likely result in greater pond coverage and potentially greater surface ablation. A shallow snowpack would retard the formation of melt ponds resulting in a larger albedo. Changes in the ice-albedo feedback could also impact interactions between the terrestrial and marine environmental with serious consequences. For example, early melting of the terrestrial snowpack would result in significant increases in the total heat input. In coastal regimes, this would hasten the melting of the shorefast sea ice, extending the ice free period and exposing the coast to more storms and erosion.
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