Tree Rings Tell of Huge Drought in Southwest

摘要

Traces of a previously unknown mul-tidecade drought period in the second century A.D. in the Southwest has been uncovered by researchers. The findings, published in Geophysical Research Letters, give evidence that extended periods of aridity have occurred at intervals throughout our past. Almost 900 years ago, in the mid 12th century, the Southwestern U.S. was in the middle of a multidecade megadrought.