Think California's current drought is bad? According to a new study, the western United States could be headed for an era of megadrought unprecedented in the last 1,000 years.
The paper, published Thursday in Science, claims the 21st century could bring prolonged drought to the American Southwest and Central Plains. California's current drought may be entering its fourth year, but in contrast, megadroughts can last many decades.
"These future droughts are very likely to be worse and longer than even the most severe droughts experienced in western North America over the last thousand years," said co-author Benjamin Cook, a research scientist at NASA's Goddard Institute for Space Studies.
The authors examined centuries-old tree rings to chart past drought. "During a dry year, the rings will be skinnier," explained Cook. "During a wet year, the rings will be wider."
They combined those historical records with 17 computer models predicting future drought in the region. Their baseline was an era of prolonged drought in the 12th and 13th century known as the Medieval Climatic Anomaly. This period may have contributed to the fall of some Native American groups in the Southwest.
Cook said unlike previous megadroughts, future dry spells will be made worse by human activity.
"These future droughts really represent a fundamental shift towards a drier climate, forced primarily by human increases in greenhouse gases and the associated warming," Cook said.
