PORTLAND, Ore. (KOIN) — Cascade Range snowpack is melting 18 days faster, on average, in regions recovering from past wildfires, a new study by the American Geophysical Union has found.

In regions like the Western U.S., where early snowmelt is already occurring due to climate change, wildfires are reportedly exacerbating the issue.

“Wildfires are further shifting the melt earlier, which could have substantial consequences for water supply and flood risks,” the study states.

In the Cascades, these melting rates were more drastic than other analyzed regions of the Western U.S., study co-author Jeremy Giovando told KOIN 6.

“Snowpack accumulation and melt are critical for water supply in the Western U.S.,” Giovando said. “As the number and size of wildfires have increased, it is important to understand how these events impact the seasonal snowpack.”

Using historical weather data recorded by climate sensors, the study analyzed snow accumulation and snow melt in 45 areas burned by wildfire and 110 areas not affected by wildfire. For the Cascades, this data includes snowpack in the burn scars of the 2003 B&B Complex Fire (90,000 acres) and the 2012 Pole Creek Fire (26,000 acres).

Deschutes wildfire history. | B&B Complex and Pole Creek Fire scars seen in northwest corner of the map. | Deschutes County

Many burned regions across the U.S. also saw changes in peak snowpack. According to the study, peak snowpack in the Cascades decreased by an average of 13% in areas recovering from wildfire. The largest differences between burned and unburned sites in the U.S. were recorded in the Eastern Cascades and Canadian Rockies ecoregions.

While the study shows a connection between changing snowpacks and wildfires, Giovando said that it is also important to consider annual changes in precipitation when looking at snowpack and melt over a period of time.

“In order to isolate the impacts of wildfire on snowpack, we attempted to remove this variability by dividing the peak snowpack magnitude by the total amount of winter precipitation,” he said. “This allows us to compare years before and after the wildfire more directly to quantify snowpack changes only due to the fire.”

In recent years, precipitation has been drastically affected by the ongoing “mega-drought” currently affecting the Western U.S. However, areas of Washington and Northern Oregon have seen significant relief within the last year. In some regions, the drought has completely subsided. While many Western states are still drought-stricken, KOIN 6 Meteorologist Kelley Bayern said that partial relief is still good news for the Pacific Northwest.

Drought conditions on Aug. 24 2021 compared with Aug. 23 2022. | NOAA

“Focusing on the western U.S., you can see major improvements to drought over just a year,” Bayern said. “Washington has seen the most relief from drought due to our record spring rain amounts across the Pacific Northwest. Exceptional drought is still present for a number of states, but the drastic decrease is still a big win.”

Although the study did not analyze any correlations between changes in snowpack and streamflow. Previous studies conducted by the AGU in 2016 concluded that early snowmelt can decrease streamflow and reduce a forest’s ability to remove carbon dioxide from the atmosphere. This can result in lower summer stream flows and longer fire seasons.

During periods of adequate or significant precipitation, early snowmelt can also lead to flooding and lower summer flows. To account for these changes, water governing agencies should consider long-term adjustments to reservoir operations following a wildfire.

“Water managers should anticipate changes to snow accumulation and [melting] following a wildfire,” the study states. “They can expect earlier initiation of snowmelt and a longer snow-free season, which may impact summer streamflow and water temperatures.”