August 19, 2008

Evidence of Century-Long Droughts Found

A stalagmite discovered in a U.S. cave has yielded detailed geological data on 7,000 years of eastern North America climate cycles.

The Ohio University-led study confirms that during periods when the Earth received less solar radiation a series of century-long droughts occurred.

Researchers led by Assistant Professor Gregory Springer said the stalagmite preserved climate conditions over periods as brief as a few years. The scientists said they found evidence of at least seven major droughts during the Holocene era.

The stalagmites from West Virginia's Buckeye Creek Cave provide an excellent record of climate cycles because that state is affected by jet streams and moisture from both the Gulf of Mexico and the Pacific Ocean, Springer said.

Other studies have gleaned climatic data from lakes, but fish and other animals tend to churn the sediment, muddying the geological record, said Assistant Professor Harold Rowe of the University of Texas-Arlington, a co-author of the study.

"(The caves) haven't been disturbed by anything," said Rowe. "We can see what happened on the scale of a few decades. In lakes of the Appalachian region, you're looking more at the scale of a millennium."

The research appears in the journal Geophysical Research Letters.