Signals of past say big droughts can hit U.S. east

Mar 24, 2011
Researchers in southern Appalachia investigate a tulip poplar tree thought to be about 300 years old. Credit: Neil Pederson, Lamont-Doherty Earth Observatory

( -- Scientists examining rings from old trees spanning the last 400 years say they show that the U.S. East Coast has suffered droughts longer and more frequent than anything recorded in modern times. With large cities like New York and Atlanta struggling in recent years to maintain water supplies during dry spells, the findings suggest such cities may be in for much worse times, should such conditions return. The study was presented this week at a conference in Santa Fe, N.M., sponsored by the American Geophysical Union.

“We can handle two- to three-year droughts, but if three- and four- and five-year droughts are possible, we’re not prepared,” said Neil Pederson, a research professor with the Tree Ring Laboratory at Columbia University’s Lamont-Doherty Earth Observatory, who created the records. The familiar scene of fights and lawsuits over is already “starting to play out here in the East,” he noted.

Pederson and his students collected cores from trees that have lived as long as 500 years, including rare old tulip poplars and hickories, as well as specimens from wooden beams in historical buildings. Because some species respond predictably by producing narrower annual rings when rainfall declines, the researchers were able to plot precipitation year by year from the 1500s on. Among other things, the cores showed three severe droughts in the 1700s in southern Appalachia that were soon followed by large die-offs of trees. The cores showed that droughts of the past 120 years—about the extent of reliable written records—have been short-lived, compared to the past ones.

Nevertheless, the recent dry spells have strained . By the middle of a 2005-2007 drought in the Southeast, Atlanta was left with only three months’ water supply, while Athens, Ga., was down to 50 days. In the last decade, New York has struggled to maintain supplies, and a 1981 drought lowered the city’s reservoirs to a third of capacity. New York has successfully reduced per capita demand for water in recent years, but Pederson says that will only partly offset the problem there. A separate 2009 study by Lamont climate modeler Richard Seager and his colleagues showed that the 2005-2007 Southeast water shortages were probably caused more by booming population and bad planning than by the relatively modest lack of rainfall. The shortages destroyed billions of dollars in crops and sparked legal battles among a half-dozen states.

Pederson says he thinks the recent shortages can be considered “human-triggered,” not the result of extraordinary weather. “These relatively minor are setting off water conservation measures and draining reservoirs,” said Pederson. “That’s the scary thing.”

This spring, he and colleagues plan to sample more in Mammoth Caves National Park, Kentucky, where many trees of great age are believed to be preserved.

Explore further: Pact with devil? California farmers use oil firms' water

More information:

Related Stories

Southwest headed for permanent drought

Jan 31, 2011

( -- The American Southwest has seen naturally induced dry spells throughout the past, but now human-induced global warming could push the region into a permanent drought in the coming decades, ...

'Killer' Southeast drought low on scale, says study

Oct 01, 2009

A 2005-2007 dry spell in the southeastern United States destroyed billions of dollars of crops, drained municipal reservoirs and sparked legal wars among a half-dozen states—but the havoc came not from exceptional ...

China drought leaves millions short of water

Mar 17, 2010

Millions of people face drinking water shortages in southwestern China because of a once-a-century drought that has dried up rivers and threatens vast farmlands, state media reported Wednesday.

Colorado River Basin vulnerable to drought

Feb 22, 2007

A National Research Council study of the Colorado River Basin found that the area could suffer severe droughts as the climate warms and population grows.

Recommended for you

Stronger action needed to transform the UK's energy system

2 hours ago

An ambitious policy package is essential for the UK to transform its energy system to achieve the deep reductions in carbon emissions required to avoid dangerous climate change, according to research led by UCL scientists. ...

Gimmicks and technology: California learns to save water

Jul 03, 2015

Billboards and TV commercials, living room visits, guess-your-water-use booths, and awards for water stinginess—a wealthy swath of Orange County that once had one of the worst records for water conservation ...

Cities, regions call for 'robust' world climate pact

Jul 03, 2015

Thousands of cities, provinces and states from around the world urged national governments on Thursday to deliver a "robust, binding, equitable and universal" planet-saving climate pact in December.

Will climate change put mussels off the menu?

Jul 03, 2015

Climate change models predict that sea temperatures will rise significantly, including in the tropics. In these areas, rainfall is also predicted to increase, reducing the salt concentration of the surface ...

User comments : 0

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.