Climate Science

Extreme Melting

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Science  30 Mar 2012:
Vol. 335, Issue 6076, pp. 1546
DOI: 10.1126/science.335.6076.1546-a

Climate models have predicted that extreme weather events will increase in frequency and intensity as greenhouse gases continue to accumulate in the atmosphere and the consequent global warming intensifies. Such a change could have tremendous practical impacts on our environment and our lives. It is of interest, therefore, to understand the mechanisms that may cause this phenomenon. One obvious part of the world toward which to look for evidence is the Arctic, where the rate of warming has been faster than anywhere else on Earth. Francis and Vavrus examined atmospheric data from the mid- and high-latitude Northern Hemisphere and identified two mechanisms that seem to contribute to the trend toward extremes, both of which have the effect of slowing down the west-to-east progression of weather systems in the northern mid-latitudes, thereby intensifying their impacts. These changes seem to be the result of growing Arctic sea-ice loss, which causes the transfer of additional energy from the ocean into the high-latitude atmosphere, and of earlier continental snow melt and drying of the soil, which increase the tendency toward high-amplitude weather patterns in summer.

Geophys. Res. Lett. 39, L06801 (2012).

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