A new study published in Science aims to assess the effect of climate change on the risk of a serious drought hitting the Southwest United States before the year 2100. Megadroughts are defined as decade-long periods of prolonged drought; megadroughts can occur when the delicate balance between soil moisture and evaporation are upset. The most recent megadrought dates back to the late 16th century and is believed to be responsible for the demise of the Ancestral Puebloan civilization.
To assess the risk of a megadrought, scientists developed a model that not only takes into account rising global temperatures, but also possible changes in rainfall caused by climate change. Their model predicts that even if rainfall patterns remain exactly as they are today (which is unlikely), the likelihood of a megadrought overwhelming the Southwest by the year 2100 is 90%. Even simulations that allowed for a 30% increase in rainfall still predicted an increased risk of megadrought.
Mitigating the risk of a megadrought relies heavily on curbing our global carbon emissions. Reducing the likelihood of megadrought to 30% requires that global temperatures stabilize below a 2°C increase, but current trends predict an increase of 4°C by the year 2100. Unless substantial strides are taken to limit greenhouse gases, a megadrought in the Southwest and other vulnerable regions may be inevitable.
Managing Correspondent: Tarraneh Eftekhari
Scientific Paper: Relative impacts of mitigation, temperature, and precipitation on 21st-century megadrought risk in the American Southwest – ScienceAdvances
Media Coverage: The Southwest Will Probably Suffer a Crippling Megadrought This Century – Popular Mechanics