California is already suffering from the worst drought in a millennium, and now new research shows parts of the Western United States are to face the same fate with decades-long "megadroughts."
"Unprecedented drought conditions" - the worst in more than 1,000 years - are to plague the US Southwest and Great Plains after 2050 with devastating impacts, according to a new study in the journal Science Advances. While previous studies have already predicted that the Southwest could dry due to global warming, this is the first to say that it could surpass the worst arid conditions seen in the United States' history, including the 1930s Dust Bowl that lasted for more than 35 years.
"Nearly every year is going to be dry toward the end of the 21st century compared to what we think of as normal conditions now," lead author Benjamin Cook, a NASA atmospheric scientist, told the Arizona Daily Star. "We're going to have to think about a much drier future in western North America."
There's more than an 80 percent chance that much of the central and western United States will have a 35-year-or-longer "megadrought" later this century, according to the researchers. And they blame this bleak future on human-caused global warming - a topic that even the US Senate can't agree on.
Cook and his colleagues based their predictions on hundreds of tree-ring chronologies from the past 2,500 years, which compiled into the North American Drought Atlas. This data indicates drought conditions over the past millennia. Compared with 17 different future climate models, the results show that droughts are likely to be worse than even the medieval dry periods during the 12th and 13th centuries, and worse than the current drought out West, which has endured for 11 of the last 14 years.
"We are the first to do this kind of quantitative comparison between the projections and the distant past, and the story is a bit bleak," co-author Jason E. Smerdon, a climate scientist at Columbia University, said in a news release. "Even when selecting for the worst megadrought-dominated period, the 21st century projections make the megadroughts seem like quaint walks through the Garden of Eden."
Already the current drought is affecting more than 64 million people in the Southwest and Southern Plains, according to NASA. And considering our use of resources and growing human population, the researchers warn that the impacts of these megadroughts are only going to get worse.
"Changes in precipitation, temperature and drought, and the consequences it has for our society - which is critically dependent on our freshwater resources for food, electricity and industry - are likely to be the most immediate climate impacts we experience as a result of greenhouse gas emissions," said Kevin Anchukaitis, a climate researcher at the Woods Hole Oceanographic Institution.
Aside from those affected directly by the drought, there are also many more indirectly affected because of the impacts on agricultural areas. Drought, of course, means more stress on crops and possibly greater water shortages in urban areas.
"We have strategies today to deal with drought - develop more drought-resistant crops, use more groundwater," Cook told Scientific American. "But if future droughts will be much more severe, the question is whether we can extend those strategies or if we need new ones."
According to Cook, the next step is trying to determine exactly how many years from now with the transition begin from harmful droughts to calamitous megadroughts- a date that is still unclear to scientists.
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