A megadrought that’s been scorching southwestern United States for the past two decades is now noted to be the worst in around 1,200 years, based on new research that analyzed tree ring patterns. Megadroughts refer to severely arid conditions that last for a couple of decades. An initial study showed that the moisture deficit seen in the southwest between 2000 and 2018 was exceeded by a megadrought in the late 1500s. Researchers used tree ring patterns to determine soil moisture levels over long timespans. An update of the study, published in Nature magazine on Feb. 14, looked at drought between 2020 and 2021, and concluded that the 22-year period was the driest period since 800 CE, exceeding the megadrought of the 1500s. “At 22-yr long, the turn-of-the-twenty-first-century drought is highly likely to continue through a 23rd year and match the duration of the shortest of the reconstructed megadroughts,” the report …