Climate Science

The Shape We're In

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Science  16 Nov 2012:
Vol. 338, Issue 6109, pp. 864
DOI: 10.1126/science.338.6109.864-c

Climate is warming—there is no doubt about it—but how fast is it happening? Different regions are warming at different rates, but the one where temperatures are increasing most rapidly is the Arctic, making it an important region to understand. Based on data from three different satellite sensors, together with temperature measurements from a number of weather stations and field observations of snow and ice conditions, Nghiem et al. report that surface melting extended across more than 98% of the Greenland Ice Sheet in July 2012. This is a rare event (similar episodes are known to have occurred only twice in the past 800 years) and, in isolation, it cannot be understood as part of a trend. However, because there is so much frozen water in the Greenland Ice Sheet and sea-level rise from its melting is a potentially serious problem, it will be important to determine how often, how extensively, and why such extreme melt events occur. Being able to observe these events so soon after they occur could provide additional opportunities to determine their impacts more explicitly and thus to reveal more clearly the shape we're in.

CREDIT: S. V. NGHIEM ET AL., GEOPHYSICAL RESEARCH LETTERS 39 (27 OCTOBER 2012) © AMERICAN GEOPHYSICAL UNION

Geophys. Res. Lett. 39, L20502 (2012).

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