Consecutive Years Of 'Snow Drought' May Become More Common In The West

Aug 9, 2019

Consecutive years of low snowpack might become more common in the Western United States. That’s according to a study out Thursday from the University of Idaho.

 

In the West, snowpack ensures much more than good skiing.

 

"Snowpack acts as a natural reservoir in the mountains," says Adrienne Marshall, a postdoctoral researcher at the university's College of Natural Resources. In the spring, she says, snowpack "runs off as a stream flow when we most need it" for irrigation, resoivoirs and animal habitats, among other things.

 

Scientists have already shown warmer temperatures due to climate change will bring less snow and will cause it to melt earlier in the year. The new study published in the journal Geophysical Research Letters, on which Marshall was the lead researcher, looked at the future variability of years with low snowpack.

 

Using data on historical conditions from 1970 to 1999 and predictive climate models from 2050 to 2079, the researchers found the variability of peak snowpack in the region will decrease. This means snow droughts — rare seasons with below average snowpack — will be more common, year after year.

A map of the Western United States show the percent of years classified as snow drought in a mid-century, high-greenhouse gas emissions scenario.
Credit Adrienne Marshall/University of Idaho

Marshall says to think of it like a declining bank account.

"One year after another, you’re taking money out of your bank account, but not really managing to put more in.”

 

With lower snowpack variability, there will be less likelihood of a big snowy year making up for the previous years' losses, "recharging the bank account," or deep groundwater sources, as Marshall put it.

 

Based on the models, which assume a high-carbon-emissions future, more snow droughts are likely in lower elevation areas in the northern part of Idaho and in the Boise Foothills. These places are warm enough to see more precipitation fall as rain versus snow. 

Marshall says additional research could examine the varied effects snow droughts have on envrionmental and social systems in the West. 

Find reporter Rachel Cohen on Twitter @racheld_cohen

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