Tree rings document ancient Western megadrought

November 21, 2011 By Bettina Boxall

Researchers say they have found new evidence of prolonged drought in parts of the West, suggesting megadroughts are not the rarity Westerners would like them to be.

Analyzing corings taken from ancient living and dead bristlecone pines in the San Juan Mountains of Colorado, University of Arizona scientists found signs of extreme drought in the 2nd century that matches or exceeds the better-known droughts of the .

The composite tree-ring chronology, extending from 268 BC to AD 2009, shows that the longest dry periods in the entire record occurred during the first four centuries AD. The most pronounced drought lasted for about five decades in the second century.

Comparing their findings with two other tree-ring studies, the researchers concluded that the 2nd century drought was regional, extending from southern New Mexico north and west into Idaho.

Connie Woodhouse, a co-author of the study that will be published in the journal , said scientists have wondered if the severe Western droughts that occurred between 900 and 1400 were unique.

The new tree ring record indicates they weren't - and could occur again. "There is no good reason that we shouldn't expect to have those," Woodhouse said.

She added that researchers are not sure of the causes of the megadroughts but speculate that above-average temperatures and persistent La Nina may have contributed to them.

Explore further: Tree-ring data gives history of droughts

Related Stories

River streamflow reconstructed to 1490

May 26, 2006

A tree-ring-based study of 508 years of the U.S. Colorado River streamflow confirms droughts have occurred that were more severe than those of 2000-04.

US southwest could see 60-year drought: study

December 13, 2010

An unprecedented combination of heat plus decades of drought could be in store for the Southwest sometime this century, suggests new research from a University of Arizona-led team.

Scientists find evidence of Roman period megadrought

November 4, 2011

A new study at the UA's Laboratory of Tree-Ring Research has revealed a previously unknown multi-decade drought period in the second century A.D. The findings give evidence that extended periods of aridity have occurred at ...

Recommended for you

Explaining crocodiles in Wyoming

September 2, 2015

Fifty million years ago, the Cowboy State was crawling with crocodiles. Fossil records show that crocs lounged in the shade of palm trees from southwestern Wyoming to southern Canada during the Cretaceous and Eocene.  Exactly ...

How wind sculpted Earth's largest dust deposit

September 1, 2015

China's Loess Plateau was formed by wind alternately depositing dust or removing dust over the last 2.6 million years, according to a new report from University of Arizona geoscientists.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.