The US may be set for severe and prolonged droughts in the coming decades, a new government study has found.
The National Center for Atmospheric Research (NCAR) says that much of the world will become increasingly dry in the next 30 years. In some regions, it says, drought may reach levels unprecedented in modern times.
Using an ensemble of 22 computer climate models and a comprehensive index of drought conditions, as well as analyses of previously published studies, the paper reports that by the 2030s, dryness is likely to increase substantially across most of the Western Hemisphere, along with large parts of Eurasia, Africa, and Australia. By later this century, many of the world's most densely populated regions will be threatened with severe drought conditions, says NCAR.
In contrast, higher-latitude regions from Alaska to Scandinavia are likely to become more moist.
While regional climate projections are less certain than those for the globe as a whole, NCAR scientist Aiguo Dai believes that most of the western two-thirds of the United States will be significantly drier by the 2030s.
Large parts of the nation may face an increasing risk of extreme drought during the century.
"We are facing the possibility of widespread drought in the coming decades, but this has yet to be fully recognized by both the public and the climate change research community," says Dai. "If the projections in this study come even close to being realized, the consequences for society worldwide will be enormous."
Other countries and continents that could face significant drying include much of Latin America, the Mediterranean, southeast and southwest Asia and most of Africa and Australia.
The study also finds that drought risk can be expected to decrease this century across much of Northern Europe, Russia, Canada, and Alaska, as well as some areas in the southern hemisphere.
However, the globe's land areas should be drier overall.
"The increased wetness over the northern, sparsely populated high latitudes can't match the drying over the more densely populated temperate and tropical areas," Dai says.