Click the link to go to the “Best of the West” page on the Western Governors website. Here’s an excerpt:
July 24, 2025
Redefining Drought: Drought is often defined as “drier-than-normal,” but if the climate is shifting, what’s considered the new normal? While a larger sample size reduces uncertainty, it could also create a baseline that isn’t representative of today’s climate.
With ample data collected via the National Integrated Drought Information System, which Western Governors helped create in 2003, The National Academies of Sciences, Engineering, and Medicine is working on a study to determine the best way to manipulate that data in ways that are the most useful for different water users.
For instance, “if you’re in a place where the precipitation is declining, such as far Western Texas or New Mexico, or possibly you’re relying on stream or river flow to irrigate your crop, and that water resource is declining, you want to be able to think ahead and be aware of the average amount of water you have access to,” said Joel Lisonbee, a senior associate scientist at the Cooperative Institute for Research in the Environmental Sciences, or CIRES, at the University of Colorado in Boulder. In those cases, it may make sense to use a shorter baseline to reflect recent trends, rather than include data from a century ago, when the climate was different.
“What we should be asking is, when should drought be defined using all available data? When should we use the whole climate record?” Lisonbee said. “There’s not one answer, and the correct answer will really depend on why you’re assessing drought in the first place.”