Maps of monsoon history

05/05/2010

Climate Change – News and Comments

Maps of monsoon history

Brendan Buckley cores a tree in Vietnam. Photo: K. Krajick, Earth Institute, Columbia U.

Asian Monsoon Failure and Megadrought During the Last Millennium” is the dramatic title of a report in Science that introduces a new Monsoon Asia Drought Atlas. Edward R. Cook and his colleagues at the Tree-Ring Laboratory of Columbia University’s Lamont-Doherty Earth Observatory have used tree-rings from 300 sites in Asian forests to reconstruct the summer “Palmer Drought Severity Index” (PDSI) across India, China and adjacent regions. PDSI is a fairly complicated reckoning of local deviations from mean conditions, originated in 1965 by Wayne C. Palmer, a climatologist in the US Weather Bureau.

In the following examples, North American data supplement the Asian PDSI, and anomalous sea-surface temperatures (SST) across the Pacific are also reconstructed.

On land, brown is abnormally dry, green is wet. On the oceans, red is abnormally warm, blue is cool. Fig. 4 in E.R. Cook et al, Science, 23 April 2010, distributed by NOAA Paleoclimatology.

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