Droughts

We may think of the Pacific Northwest as rain-drenched, but new research led by scientists at the University of Pittsburgh shows that the region could be in for longer dry seasons, and is unlikely to see a period as wet as the 20th century any time soon.

Some of the worst droughts to hit North Africa in the last 900 years have occurred recently—in the late 20th century—according to an analysis of tree rings that has provided the most lengthy and detailed climate record yet for this sub-tropical region on the Mediterranean.

Global Warming Could Worsen Newly Seen Pattern  

Researchers have developed the first year-by-year record of rainfall in sub-Saharan West Africa for the past 3,000 years, and identified a daunting pattern: a 30-to-60-year cycle of serious droughts that last a decade or more, punctuated by killer megadroughts that last for centuries.

Dec 10, 2007--Scientists from Columbia University’s Lamont-Doherty Earth Observatory will report this week on vital topics including new evidence of the effects of climate change; technologies to confront it; studies of eastern U.S. earthquake risk; and previously unseen inner workings of the deep polar ice caps.  The reports will be presented at the fall 2007 American Geophysical Union (AGU), the largest earth-sciences gathering in the world, Dec. 10-14 in San Francisco.

Researchers from the Lamont-Doherty Earth Observatory of The Earth Institute at Columbia University have used 835 annual tree-ring chronologies based on measurements from 20- to 30-thousand tree samples across the United States, Mexico, and parts of Canada to reconstruct a history of drought over the last 2005 years. The resulting drought reconstructions have been organized into a North American Drought Atlas CD-ROM, the first of its kind, which maps year-by-year occurrences of droughts.