U.S. could be facing megadrought

A megadrought is possible for a large area of the United States in the not-too-distant future.

Serious drought conditions experienced in recent years across the Southwest, Midwest and Far West may seem insignificant in the years ahead if a new NASA-Cornell University study is correct in its long range climate outlook.

The study, released just last week, says a megadrought is possible for a large area of the United States in the not-too-distant future, a drought that could last for several decades, bringing with it life-and-planet-changing developments that could spell disaster not only to farmers but the population-at-large.

The study is drawing a great deal of attention, some of it negative from those who believe climate change in general is either unfounded or greatly over-rated. But authors of the study say scientific evidence supports their conclusion and warn that how we manage water resources in coming years will be critical if their predictions of a long-lasting drought run true.

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The study, published Feb. 12 in the journal Science Advances, an online publication of the American Association for the Advancement of Science, claims a major drought could form later this century and could last for as much as 30 years.

"The results were striking. As a society, we’ve weighted the dice toward megadrought. Data clearly point to a high risk in the Southwest and Great Plains as we continue to add carbon dioxide into our atmosphere," said Toby Ault, Cornell associate professor of earth and atmospheric sciences in a university report last week. "However, if we manage to get serious about lowering greenhouse gases within the next 10 years, we could face a lower risk."

NASA's Benjamin Cook and Jason Smerdon served as co-authors of the study.

Higher temperatures

According to the research team, the study, titled "Unprecedented 21st Century Drought Risk in the American Southwest and Central Plains and Drought Risk in Western North America," warns of higher regional temperatures amplifying possible late-century droughts and predicts extreme challenges facing agriculture and government that will face extreme challenges managing water needs exaggerated by a sustained period of exceptionally dry weather.

While researchers agree that human activity is adding to the elevated risk and timing of climate change, they also agree that a normal cyclic change in climate is also at play. By examining tree rings and other physical evidence, the report indicates previous research identified a period of time called Medieval Climate Anomaly (A.D. 1100-1300) when megadroughts were common.

By analyzing data from 17 state-of-the-art global climate models, Cook, Ault and Smerdon learned that western North America’s future drought risk exceeded even the driest centuries of the Medieval Climate Anomaly.

According to the report published in the Cornell Chronicle, The role of climate change in causing extreme heat waves, drastic rainfall, negative impacts on human health and threatened food security have received more attention recently than megadroughts. However, Ault views prolonged drought risk as yet another natural hazard that becomes more likely from human activity.

Manageable hazard

"Hurricanes and tornadoes are natural hazards and they strike fast. A megadrought is a natural hazard, but it unfolds slowly – over a period of decades," said Ault. “It’s just another natural hazard and one we can manage."

The study indicates that while less rain will fall during the upcoming megadrought period, of greater concern will be elevated heat levels which will rob moisture from soils, further complicating food production.

There's at least an "80 percent chance of a megadrought in the aforementioned regions" if climate change continues unabated, Ault says.

A megadrought is defined as a drought that lasts for decades or longer, such as those that scorched portions of the West in the 12th and 13th centuries.

"Natural droughts like the 1930s Dust Bowl and the current drought in the Southwest have historically lasted maybe a decade or a little less," Ben Cook, climate scientist at NASA's Goddard Institute for Space Studies and lead author of the study, said in a statement.

Ault, a faculty fellow with the Atkinson Center for a Sustainable Future, wants to lower carbon dioxide emissions quickly.

"The time to act is now. The time to start planning for adaptation is now," he said. "We need to assess what the rest of this century will look like for our children and grandchildren."

The National Science Foundation and NASA funded the research. Ault was supported by a startup grant from the College of Agriculture and Life Sciences.

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