Study envisions unprecedented drought

Tuesday, February 17, 2015 - 05:00 YT&Twebzine

Long and relentless droughts should be expected in the American Southwest and Central Plains.

The Dust Bowl was nothing, as it turns out, compared with droughts predicted for the last half of this century.

There is an “unprecedented risk” of drought, warns a Feb. 12 study published in Science Advances. Researchers project that droughts in the Southwest and Central Plains will be longer and drier than anything experienced in the last 1,000 years.
Examining the later half of the 21st century (2050-2099), researchers found that the more greenhouse emissions increase, the bigger the problem. Consider that the current likelihood of a megadrought -- a drought lasting more than three decades -- is 12 percent:

If greenhouse gas emissions continue to increase at the current rate throughout the 21st century (researchers refer to this as "business as usual"), there is an 80 percent likelihood of a decades-long megadrought in the Southwest and Central Plains between 2050 and 2099.
If there are aggressive attempts to slow greenhouse gas emissions, the likelihood of megadrought still reaches more than 60 percent.

     Researchers Benjamin I. Cook of the NASA Goddard Institute for Space Studies, Toby R. Ault of Cornell University and Jason E. Smerdon of Ocean and Climate Physics, Lamont-Doherty Earth Observatory of Columbia University, based their analysis on projections from climate models, including one sponsored by NASA.
     "Ultimately," the authors wrote, "the consistency of our results suggests an exceptionally high risk of a multidecadal megadrought occurring over the Central Plains and Southwest regions during the late 21st century, a level of aridity exceeding even the persistent megadroughts that characterized the Medieval era."
     This study is the first to compare future drought projections directly with drought records from the past 1,000 years, according to NASA. Researchers used a tree-ring database to study older droughts. By comparing the modern drought measurements with tree rings in the 20th century for a baseline, the tree rings can be used to establish moisture conditions over the past 1,000 years.

This story was compiled with information from Advance Sciences and a NASA news report.

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