Researchers Devise New Method for Predicting Droughts

Scientists at Argonne National Laboratory have developed a new method to assess the probability of extreme drought conditions in several different regions of the U.S. over the remainder of the century. Specifically, the researchers devised a new technique to better understand and forecast “flash drought” events.

Flash droughts intensify rapidly over a period of a few weeks and often catch forecasters by surprise. Previous research found that changing climate conditions are likely to increase the probability of flash droughts. In addition, a study in February concluded that the current drought affecting the western U.S. is the worst drought in 1,200 years and has been exacerbated by climate change. Traditionally, drought is measured by gauging precipitation rates. But in this study, the scientists turned to a new measure called vapor pressure deficit, or VPD. VPD is calculated based on a combination of temperature and relative humidity and consists of the difference between how much water vapor the air can hold when saturated and the total amount of water vapor available. “An extended period of higher-than-average VPD can mean that a drought is occurring,” said Argonne environmental scientist Brandi Gamelin. ​“We’re looking at drought differently by bypassing precipitation altogether — to primarily look at the effect of temperature and future temperature changes on drought.” The study’s findings are especially applicable in the Midwest, Northwest, and California’s Central Valley.

Relatedly, researchers from the University of Connecticut discovered a way to predict flash droughts by looking at plants. Also, WaterISAC previously reported on research that advocated for changing the definition of drought based on new climate realities. “The projected worsening of droughts as a result of global warming is likely to have significant consequences in terms of crop loss, wildfires, and demand for water resources,” said Rao Kotamarthi, an Argonne environmental scientist and author of the new study. Read more at Argonne National Laboratory or access the full study here.