Climate Science

Dust in the Wind

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Science  24 Apr 2009:
Vol. 324, Issue 5926, pp. 441
DOI: 10.1126/science.324_441b

The ice core record of the past 800,000 years shows that glacial periods tend to be cold and dry, with above-average amounts of wind-blown dust in the air. In Antarctica, for example, where most of the dust trapped in the ice comes from southern South America, the closest terrestrial neighbor to the cold continent, dust was deposited during the last glacial period at a rate between 20 and 50 times higher than today. That general pattern makes intuitive sense, but what was the cause of the elevated dustiness? Sugden et al. show that dust peaks in Antarctic ice cores from the last glacial period occurred when rivers of glacial meltwater deposited sediment directly onto outwash plains in Patagonia, where the dust was easily mobilized by the stronger glacial winds, and that they were absent when the glaciers terminated directly into pro-glacial lakes. These observations may help explain why dust concentrations in Antarctic ice decreased before the main phase of warming occurred in Antarctica, when sea level began to rise and Southern Hemisphere sea-ice extent started to shrink.

Nat. Geosci. 2, 281 (2009).

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