by Julie Freydlin Tuesday, May 28, 2013
A devastating drought currently affects almost half of the contiguous U.S., with conditions expected to persist or intensify in many of these areas, according to an outlook released this month by the National Integrated Drought Information System.
The U.S. is no stranger to drought; the last 15 years have brought some of the most severe and widespread droughts the country has seen since the late 19th century. But the last few years have been especially tough. In 2011, many south-central states, including Texas, experienced D4 drought conditions — the highest drought rating on the government’s drought scale — from June through December. For some of these areas, drought lasted through the winter of 2011-2012, only to intensify again in the summer and spread to a wider area, affecting 65 percent of the contiguous U.S. at its peak — although D4 intensities affected a smaller area than the year before.
Drought eased up on the East Coast over this past winter and spring. But many of the Central and Western states never fully recovered and as of mid-May, 46 percent of the contiguous U.S. is experiencing some level of drought, with parts of New Mexico, Colorado and Kansas experiencing D4 intensities already. As a result, spring and summer streamflows are expected to fall below average levels in many Western states. Current lake levels in Central and Western Texas have already dipped below their 2011 drought levels, and many states are asking residents to conserve water.
“Some of these same areas were extremely hard hit during the south-central U.S. drought of 2011,” says Brad Rippey, a meteorologist at the U.S. Department of Agriculture. “That helps to explain why the situation is so bad in these areas — they never completely recovered in 2012.” The new outlook projects that many areas currently affected by more moderate D3 drought are expected to slip into D4 conditions as drought persists or intensifies through the summer.
According to the outlook, many of the affected states are also expected to experience higher-than-average temperatures this summer, with Colorado, New Mexico and Texas bearing the brunt of the heat. Warmer temperatures, in turn, can lead to decreased precipitation, Rippey says, as a result of a “feedback loop associated with drought. That is to say, dry soils and drought-affected plants don’t release much moisture into the air, which leads to [less rain] when cold fronts pass through.”
In addition, Arizona, California, Colorado, New Mexico, Oregon and Utah have a higher potential for wildfires than normal, in part because year-to-date precipitation — especially in California, Oregon and Washington — is more than 30 centimeters below average. Although the likelihood of fires does not depend on drought alone, “a period of hot, dry, windy weather during drought may make fires more likely,” Rippey says. A wildfire broke out on Monday in Los Padres National Forest north of Santa Barbara, Calif.
Extreme droughts have been in the news a lot lately, he says. “Events such as the Texas drought of 2011 or the U.S. drought of 2012 are statistically more likely due to the climate change we’ve experienced over the last several decades.”
Unfortunately, the U.S. is ill-equipped to deal with the effects of drought, says Don Wilhite of the University of Nebraska-Lincoln, the founding director of the National Drought Mitigation Center. The country’s current approach to dealing with drought involves reacting after a drought occurs to minimize the amount of damage done, rather than acting to create resilient infrastructure and decrease vulnerability to drought, he says.
To deal more effectively with drought, Wilhite says, the U.S. government needs to develop early warning programs and preparedness plans. “Over recent decades we have seen our vulnerability to drought increase and spread to many sectors beyond just agriculture,” he says. “All states and other entities need to adopt a more proactive philosophy of preparedness for drought.”
An updated drought outlook will be released by the National Weather Service in early June.
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