AGU: How wildfires affect snow in American west

25 August 2022

USA – Fresh powder does more than support winter sports. Snowmelt flows into streams, where it helps sustain agriculture, supports natural ecosystems, and provides drinking water. But wildfires are threatening snowpacks, and research on wildfire’s impact on snow water equivalent generally focuses on localized areas, with varying methods and conflicting results.

Now, Giovando and Niemann set about rectifying this situation with data from the Snow Telemetry system, or SNOTEL, which uses automated sensors to measure snow depth and other aspects of weather at hundreds of sites around the western United States. The researchers compared 45 burned SNOTEL sites to similar unburned sites. They found that when burned regions were at their snowiest, they obtained, on average, 13 percent less water from snow than their unburned counterparts. Snow melted completely 9 days earlier in burned regions compared to unburned areas.

Giovando and Niemann also estimated how climate change alone affects snowmelt by comparing snow at unburned sites before and after fires hit nearby sites. Fifty-six percent of these sites saw their maximum snowpack earlier in the season, and 78 percent percent lost their snow earlier in the season. However, 62 percent of unburned regions saw an increase in their maximum snowpack over the time period analyzed.

The results of this study suggest that although climate change has affected the timing of snowmelt, wildfires exacerbate this change and can also have a larger effect on the amount of water obtained from snow. (Water Resources Research, https://doi.org/10.1029/2021WR031569, 2022)

25. August 2022/by GFMCadmin