Climate change could signal prolonged droughts in American Southwest
Think the 1930s “Dust Bowl” was bad in the American West? Scientists have found evidence of “mega-drought” events that lasted centuries to millennia in the same region during warm, interglacial periods in the Pleistocene era (370,000-550,000 years ago). The evidence heightens concern over how the region will react to the modern day global temperature spikes.
The American Southwest is already predicted to get pretty dry during climate change, due to a drop in winter precipitation that would increase evaporation rates and lead to smaller snow packs that normally provide water during the warmer months.
Led by University of New Mexico earth scientist Peter Fawcett, the paper published in this week’s journal Nature discusses the discovery of extreme arid conditions in the Valles Caldera region of New Mexico during the warmest phases of interglacials, when the mean annual temperature was comparable or higher to that of modern day temperatures.
In one interglacial period they studied, temperatures rose almost 10 degrees Fahrenheit, leading at first to an abundance of vegetation such as oak and juniper that like warm conditions. However, as temperatures persisted the record shows a collapse in drought-resistant species and the Valles Caldera lake dried out, indicating a drought that scientists estimate lasted several thousand years. They write:
Our results strongly indicate that interglacial climates in the southwestern US can experience prolonged periods of aridity, lasting centuries to millennia, with profound effects on water availability and ecosystem composition. The risk of prolonged aridity is likely to be heightened by anthropogenic forcing.
The droughts they’ve studied make the 10-year Dust Bowl look like a blink in time.