Drought assessment has been outpaced by climate change: empirical arguments for a paradigm shift

Erroneous assumptions of climate stationarity are still prevalent in US water resource management, despite accelerating climate change. The US drought detection system, which allocates billions in emergency funds, relies on 60-year (or longer) records for drought characterization. This study demonstrates, using data from 1,934 US Global Historical Climate Network (GHCN) sites, that conclusions based on long climate records significantly bias drought severity assessments. This bias stems from assuming early and mid-20th-century conditions are as probable in today's climate. Numerical simulations show that drought assessment error is minimal with shorter climatology lengths (~30 years) and increases with longer record lengths in rapidly changing climates. The study argues for incorporating climate non-stationarity into contemporary assessments for more accurate drought risk portrayal.

Zachary H. Hoylman, R. Kyle Bocinsky, Kelsey G. Jencso