For nearly a quarter-century, the U. S. Drought Monitor has served as the nation's go-to resource for assessing drought conditions. This weekly map, compiled by a team of experts, plays a crucial role in directing federal aid and informing water management decisions across the country. However, a new study suggests the system may be falling behind in the face of a rapidly changing climate.

Researchers at Dartmouth College analyzed data spanning 2000 to 2022, focusing on six key climate and hydrological variables that feed into the Drought Monitor's classifications. Their findings revealed a concerning trend:certain regions, particularly in the American West, Southwest, and Deep South, were experiencing extreme droughts far more frequently than the established thresholds suggested.

"The system we use for emergency response to drought conditions is being co-opted by a changing climate, " explains Justin Mankin, lead author of the study and co-chair of the National Oceanic and Atmospheric Administration's Drought Task Force. "Exceptional" droughts, categorized as D4 on the monitor's scale, were once considered rare occurrences. The study found these severe conditions were becoming alarmingly commonplace in many areas.

For instance, parts of California endured severe drought conditions for a staggering 18% of the 23 years studied – a period nine times longer than the Drought Monitor's estimates for such an event. This discrepancy highlights a potential gap in the system's ability to accurately reflect the new normal brought on by climate change.

The consequences of this outdated approach could be dire. Federal aid programs are often triggered by specific drought classifications on the Drought Monitor. If the current system underestimates the severity of drought conditions, regions facing persistent dryness may be denied critical resources needed to mitigate the impacts.

The researchers acknowledge the complexity of the issue. The Drought Monitor relies on expert analysis alongside objective data, making it a dynamic tool. However, they emphasize the need to re-evaluate the thresholds used to define drought categories. A system designed for a historically stable climate may not be effective in a world characterized by increasing aridity.

"The challenge for federal authorities, " says Mankin, "is making sure the Drought Monitor remains effective as periodic emergencies become persistent new realities. " The ongoing research underscores the urgent need to adapt drought monitoring systems to the evolving climate landscape. This will ensure they continue to provide accurate assessments and serve as a reliable foundation for informed decision-making in a water-stressed future.