The western United States continues to struggle with the worst dry spell since the 1930s, and an international report on climate change predicts more and worse droughts to come (see "From Bad to Worse," in this week's issue). As scientists work to understand what triggers droughts, a new finding suggests that the causes may be more complex than many have supposed.
Researchers recently pieced together the most comprehensive history yet of drought in the Great Plains region. The record covers the 10,000 years since the end of the last ice age. This new time line show