PNAS - In Western US, Scientists Discover A 28% Increase In How Long Snow Droughts Last
EDIT
Most of us know a bad drought when we see one: Lakes and rivers recede from their normal water lines, crops wither in fields, and lawns turn brown. Usually we think of these droughts as being triggered by a lack of rain, but scientists also track drought in other ways.
“The common ways to measure droughts are through precipitation, soil moisture and runoff,” says Laurie S. Huning, an environmental engineer at the University of California, Irvine. Her most recent work adds another dimension to that by looking at water stored in snowpack.
Huning is the co-author of a study in the Proceedings of the National Academy of Sciences, with U.C. Irvine colleague Amir AghaKouchak, which developed a new framework for characterizing “snow droughts.” These can occur when there’s an abnormally low snowpack, which may be triggered by low precipitation, warm temperatures or both. Their research is timely. This winter, southwestern states have received just a quarter to half of the average snow-water equivalent —the amount of water held in the snowpack — the key metric for determining a snow drought.
And that can have sweeping impacts. The water content of a snowpack can change the amount and timing of when runoff occurs, and that has implications for wildlife, ecosystems, water resources, flood control, hydropower and drought mitigation. Snow droughts can also have far-reaching effects on agriculture — and economies. California’s Central Valley, the heart of its agriculture industry, relies on snow melt from the Sierra Nevada. The state saw $2.7 billion in losses in the sector following low precipitation and warm temperatures during 2014-2015.
EDIT
The study aims to solve that. Huning and AghaKouchak have developed a standardized snow-water equivalent index in an effort better characterize and compare the duration and intensity of snow droughts around the world. The results already reveal some areas of concern. Looking at data from 1980 to 2018, the researchers found a few hotspots where snow-droughts became longer and more intense during the 21st century.
The most notable area was the western United States, which saw a 28% increase in the length of periods of snow drought. Eastern Russia and Europe also saw increases, though less severe. And on the flip side, some areas saw a decrease in snow drought duration, including the Hindu Kush, Central Asia, greater Himalayas, extratropical Andes and Patagonia. “It’s important to remember that not only does the snowpack vary but the impact that it has differs across the world,” says Huning. Huning hopes the framework developed for the study can help water managers better understand the amount and timing of snowmelt, and to integrate that with drought monitoring systems to recreate better resiliency and management of resources.
EDIT
https://therevelator.org/snow-droughts-west/