Climate change made a southwestern U.S. drought one of the worst in 1,200 years
The drought in southwestern North America that lasted from 2000 to 2018 is among the most severe to strike the region in the last 1,200 years, a new study finds. Tree ring–based reconstructions of past climate reveal just one drier 19-year period: a powerful “megadrought” in the late 16th century. The recent drought, researchers say, was made 47 percent more severe by human-caused climate change. Tree rings are yearly growth bands of variable width, depending upon the ready availability of water. Using tree ring records from 1,586 sites across the western United States and northwestern Mexico — amounting to thousands of trees — hydroclimatologist Park Williams of Columbia University and colleagues created a climate history for the region going back to about the year 800. Between about 850 and 1600, several decades-long, intense “megadroughts” struck the region, on a scale not seen again until the present day, the researchers report in the April 17 Science. A particularly devastating drought that lasted from about 1575 to...