Climate Change – News and Comments
Maps of monsoon history
“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.