The American Southwest has suffered from drought conditions since the year 2000. The drought has reduced water supplies, devastated farmers and ranchers, and it has helped to fuel numerous wildfires across the region. It has generally been considered to be worst in 500 years.
According to a recent analysis, the drought has become so severe that it has actually led to the driest two decades in at least 1,200 years and the changing climate is largely responsible. The summer of 2021 was especially dry; about 2/3 of the West was in severe drought conditions.
Scientists at UCLA used tree ring data to gauge drought. Based on that analysis, 2000-2021 is the driest 22-year period since 800 A.D. which is as far back as the data goes.
The study confirmed the role of temperature, more than precipitation, in driving exceptional droughts. Precipitation levels can go up and down over time and can vary in different regions. But the ongoing emissions of greenhouse gases into the atmosphere are causing temperatures to generally rise over time. Warmer temperatures make the air more capable of pulling water out of the soil, out of vegetation, out of crops, and out of forests. All of that makes drought conditions more severe.
A megadrought is generally considered to be one that is both severe and long. But even during one, there can be wet years. 2005 was a notable one. But there must be enough consecutive wet years to actually end a drought.
Several previous megadroughts over the past 1,200 years lasted as long as 30 years. So, the current drought is in full swing and may go on for a long time to come.
Photo, posted September 25, 2021, courtesy of David Sierralupe via Flickr.