INCREASE IN THE ASIAN SOUTHWEST MONSOON DURING THE PAST FOUR CENTURIES

Climate reconstructions reveal unprecedented warming in the last century, however little is known about trends in aspects such as the monsoon. We reconstructed the monsoon winds for the last 1,000 years using fossil Globigerina bulloides abundance in box cores from the Arabian Sea, and found that monsoon wind strength increased during the past 4 centuries, as the northern hemisphere warmed. We infer that the observed link between Eurasian warmth/ snow cover and the SW monsoon persists on the centennial scale. Alternately, the forcing implicated in the warming trend (volcanic aerosols, solar output, greenhouse gases) may directly affect the monsoon. Either interpretation is consistent with the hypothesis that the SW monsoon strength will increase during the coming century as greenhouse gas concentrations continue to rise and northern latitudes continue to warm.