The most important recurring climate system in the world, theasian monsoon, affects more than half of the global population. However, the lack of long-term climate data has limited knowledge of its true nature.
Now, researchers from Columbia University in New York (USA) have presented, after 15 years of study,the most comprehensive record of Asian droughts, called MADAmade possible by sampling hundreds of ancient trees. The team has studied tree rings (dendrochronology), taking advantage of the fact that rain determines the width of their annual growth.
Reconstruction of themonsoon variability of the last 700 yearscovers three key climate events: the late part of the Medieval Climate Anomaly, the Little Ice Age, and the contemporary period of human-caused climate change. The new atlas also records the years in which the monsoon was absent, and thereforedocuments some droughts that affected humanity.
Catastrophic droughts
Tree-ring records reveal at least four major disaster-related droughts in history . Research suggests that weather may have played an important role in the fall of the Chinese Ming dynasty in 1644 . According to the scientists, the rings provide additional evidence of a severe drought in China, especially in the northeast of the country, near Beijing, and suggest that it may have influenced the rebellions. The other droughts are those from 1756 to 1768 in what is now Vietnam, Myanmar, and Thailand; that of the period from 1790 to 1796 in eastern India; and the one from 1876 to 1878, the effects of which were felt in the tropics and caused famines that killed more than 30 million people .
MADA thus details the “footprints” of the Asian monsoon on Earth since 1300. In the future it could be used to compare sea surface temperature patterns with monsoon precipitation and improve the climate model for much of the world.
