Climate Science

Ski While You Can

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Science  05 Mar 2010:
Vol. 327, Issue 5970, pp. 1181
DOI: 10.1126/science.327.5970.1181-c

Contemporary global climate change is a phenomenon defined in large part by the rapid and substantial warming it includes. During the last glacial period, the climate of the Northern Hemisphere experienced numerous rapid, large warming episodes, termed Dansgaard-Oeschger (DO) events after the Danish and Swiss researchers who documented them through ice-core studies. Can the past be used to help us understand what other impacts modern global warming may bring? In an attempt to garner such insight for the American Southwest, Asmerom et al. present oxygen isotopic data from a well-dated stalagmite recovered from central New Mexico. The oxygen isotopic composition of calcite in this speleothem is a proxy for the relative amounts of summer precipitation (from the Gulf of Mexico) and winter precipitation (from the Pacific Ocean) received at the sample site. What the authors find is an excellent match to the record of DO events, which they interpret as a result of a shift of the polar jet stream and Northern Intertropical Convergence Zone to the north during warm periods. This change in turn causes a reduction in winter precipitation and consequently greater aridity. If that same response to warming occurs in the future, an already drought-prone region could become even drier, with significant consequences for the population that lives there.

Nat. Geosci. 3, 114 (2010).

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