Researchers Warn Of 'Megadrought'

Drought woes could get worse, last longer, researchers predict.

Published on: May 29, 2013

While today's drought is on our minds, a look back to the great drought of 2000-2004 (and even into 2008 in parts of the West) provides a perspective to consider.

And, if climate warming continues to wear away at our atmosphere, there may be "megadroughts" in our future.
All this is the meat of a "Natural Geoscience" report co-authored by AmeriFlux former science director Beverly Law, an Oregon State University College of Forestry professor of global change biology and terrestrial systems.

"The 2000-2004 drought was the worst in 800 years," she says. "More of the same may be in the future."

That's the reason the report believes that the global warming conditions that caused the drought, which are still active today, may have set the mark as a "new normal" for the next 100 years.

Droughts impact the West may only be the beginning, according to some researchers predicting a major dry period to come.
Drought's impact the West may only be the beginning, according to some researchers predicting a major dry period to come.

The drought curbed carbon sequestration by more than 50%, "and that's tremendous," she notes of the report which covers the western U.S. as well as parts of the southwest and western Canada.

Crop production in the West declined by 5% during the 2000-2004 drought, she says. The carbon sink in the region "could disappear" she adds.

Parts of the West that are dry can get drier, she predicts, although the 2000-2004 drought report conclusions may not apply to today's drought.

 "We're talking different regions here, and different factors affecting each," she explains.

Nevertheless, the 2000-2004 drought in the West was a catastrophic event, with some observers calling it the worst such incident since the Dust Bowl.

Climate models used today "underestimate" drought severity, she believes. "I believe there will be megadroughts in the next 100 years in the West,"  Law says. "Expect to see more of these," she says of the 2000-2004 drought.

At the root of the problem is human-generated carbon dioxide spewed into the atmosphere, says Law, who notes that while the report did not make remedial recommendations, it should be a concern to everyone, including farmers, to reduce their emissions.

"We are seeing a continuing forest mortality, and that impacts the ability to sequester carbon," she warns. During the 20000-2004 drought, "carbon sequestration form this region was reduced by half, and if global emissions don't come down, the future will be even worse."

Drought's impact on agriculture comes in many ways, but the greatest hit may be in the reduction in photosynthesis dry periods create. During the 2000-2004 drought, western farmers saw a 51% decline in gross photosynthesis over the four-year period, Law says.

The National Science Foundation-supported research by 10 scientists was also funded by NASA and the U.S. Department of Energy.

The lead author was Northern Arizona University's Christopher Schwalm. Other collaborators include the University of Colorado and University of California-Berkeley, the University of  British Columbia and San Diego State University.