Climate change has outpaced drought assessment

Dry conditions drop water levels in Utah. Credit: Drought.gov

Despite the acceleration of climate change, assumptions of a stationary climate are still incorporated into the management of water resources in the U.S., with a preference towards 60-year (or longer) observation record lengths for drought characterization. Bias emerges by assuming that conditions from the early and mid-20th century are as likely to occur in today’s climate. In a new study funded in part by NIDIS, researchers from the Montana Climate Office evaluated the degree to which assumptions of a climate stationarity may bias drought assessment.

The study reveals that drought assessment error is relatively low with short climatology lengths, and error (with respect to the more recent climate) can increase substantially when using longer reference frames where climate is changing rapidly.

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