As if we weren’t in enough of a pickle, a new study claims that the western U.S. is in the midst of a megadrought affected by climate change.
“We now have enough observations of current drought and tree-ring records of past drought to say that we’re on the same trajectory as the worst prehistoric droughts,” the study’s lead author Park Williams, a bioclimatologist at Columbia University’s Lamont-Doherty Earth Observatory, said in a statement. “We’re no longer looking at projections, but at where we are now.”
Researchers say the 19-year drought the region has experienced since 2000 is as bad as any in the past 1,200 years. The study, published in the journal Science, looked at part of northern Mexico and the U.S. states of California, Oregon, Nevada, Idaho, Colorado, Utah, Wyoming, Arizona and New Mexico. So far, the only earlier drought that rivals the current one was one in the Medieval period that began in 1575. The researchers used tree ring data to estimate annual soil moisture for pre-modern data. They found four multi-decade droughts, aka megadroughts, dating back to 800 A.D.
Natural variables play a role in drought. But studying the current drought, scientists put almost half the blame, or 47%, on global warming. “There is no reason to believe that the sort of natural variability documented in the paleoclimatic record will not continue into the future, but the difference is that droughts will occur under warmer temperatures,” said Connie Woodhouse, a University of Arizona climate scientist. Woodhouse was not involved in the study. “These warmer conditions will exacerbate droughts, making them more severe, longer, and more widespread than they would have been otherwise.”
The 20th century could also be blamed for giving humans false optimism. It was the wettest century in the whole 1200-year study, which helped the population boom. “The 20th century gave us an overly optimistic view of how much water is potentially available,” said co-author Benjamin Cook of Lamont and the Goddard Institute for Space Studies. The 21st century looks like it will be bringing drier decades.
Via Earth Institute
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