Tree rings document ancient Western megadrought

Nov 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: Clean air: Fewer sources for self-cleaning

5 /5 (2 votes)
add to favorites email to friend print save as pdf

Related Stories

Scientists find evidence of Roman period megadrought

Nov 04, 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 ...

US southwest could see 60-year drought: study

Dec 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.

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.

Recommended for you

Clean air: Fewer sources for self-cleaning

49 minutes ago

Up to now, HONO, also known as nitrous acid, was considered one of the most important sources of hydroxyl radicals (OH), which are regarded as the detergent of the atmosphere, allowing the air to clean itself. ...

There's something ancient in the icebox

49 minutes ago

Glaciers are commonly thought to work like a belt sander. As they move over the land they scrape off everything—vegetation, soil, and even the top layer of bedrock. So scientists were greatly surprised ...

Image: Grand Canyon geology lessons on view

7 hours ago

The Grand Canyon in northern Arizona is a favorite for astronauts shooting photos from the International Space Station, as well as one of the best-known tourist attractions in the world. The steep walls of ...

First radar vision for Copernicus

7 hours ago

Launched on 3 April, ESA's Sentinel-1A satellite has already delivered its first radar images of Earth. They offer a tantalising glimpse of the kind of operational imagery that this new mission will provide ...

User comments : 0

More news stories

There's something ancient in the icebox

Glaciers are commonly thought to work like a belt sander. As they move over the land they scrape off everything—vegetation, soil, and even the top layer of bedrock. So scientists were greatly surprised ...

Clean air: Fewer sources for self-cleaning

Up to now, HONO, also known as nitrous acid, was considered one of the most important sources of hydroxyl radicals (OH), which are regarded as the detergent of the atmosphere, allowing the air to clean itself. ...

Turning off depression in the brain

Scientists have traced vulnerability to depression-like behaviors in mice to out-of-balance electrical activity inside neurons of the brain's reward circuit and experimentally reversed it – but there's ...

Thinnest feasible nano-membrane produced

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...