Pre-Columbian America was plagued by decades-long megadroughts
In the August issue of Physics Today, climate scientists Toby Ault and Scott St. George share a pair of startling research findings. Between roughly 800 and 1500 CE, the American West suffered a succession of decades-long droughts, much longer than anything we’ve endured in modern history. And statistical models suggest that, as the climate warms, such megadroughts are increasingly likely to return.
Ring-width analyses provide the most complete set of data on past moisture levels. But researchers have other ways of determining those conditions. Here are four of them: