Multimedia | Scientists Reconstruct the History of Drought for North America

Little is known about what triggers major droughts, yet they occur all across North America, often having serious economic and social impacts. Researchers from the Lamont-Doherty Earth Observatory have used 835 annual tree-ring chronologies based on measurements from 20 to 30 thousand treeamples across the United States, Mexico and parts of Canada to reconstruct a history of drought over the last 2005 years.