As record wildfires and historic drought continue to plague parts of the western United States, researchers have now learned that burn scars left in the Rocky Mountains are affecting the viability of watersheds critical to dozens of millions of Americans.
Burn scars in high-elevation regions of the Rocky Mountains are dramatically affecting snowpack and runoff on water resources that provide drinking and irrigation water to much of the state, according to Colorado State University researchers. united
Daniel McGrath, a geoscientist and professor at CSU, studied burn scars with his team across Colorado to see how fires along critical watersheds deteriorate and melt.
McGrath specifically focused his studies on the Cameron Peak Fire burn scar. The Cameron Peak Fire is Colorado’s largest fire on record, burning more than 208,000 acres in 2020.
The Cameron Peak Fire was one of several wildfires that devastated the Colorado mountains in 2020, many of which became some of the largest wildfires in Colorado history.
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“These fires are burning at higher levels and higher elevations,” McGrath told CBS News Colorado’s Dillon Thomas. “We saw more wildfires (in high-elevation Colorado) that year than the previous 36 years combined.”
Millions of Americans depend on Colorado’s winter snowstorms to provide drinking and irrigation water during the summer and fall.
Climatologists have been tracking the impact of climate change on Colorado’s water resources for decades.
However, now that wildfires are becoming more frequent and harder to contain, McGrath set out to learn how the annual snowpack reacts to the newly charred terrain.
What McGrath and his team learned was troubling, especially after realizing that the effects of a burn scar can take more than a decade to correct.
“As we see more and more of these fires affecting the higher elevations of the West where we accumulate this deep seasonal snowpack, there are concerns about what that means for those (water) resources,” he said. McGrath. “What we found in the Cameron Peak Fire specifically is that we saw a 20 percent reduction in the amount of accumulated snow.”
Wildfires like the Cameron Peak Fire burn so hot, with flames so high that the canopy is often destroyed. With no header, the snow all winter falls directly over the burned trees and onto the ground.
“At first you might think you might see an increase in snow accumulation because you don’t have that interception happening. But as we lose the forest, we see increases in wind speed and other flows through the forests that they can lead to sublimation, which is when it goes from a solid state to a vapor state,” McGrath said.
Not only is less snow retained on the ground, but what remains in the snowpack also melts much faster than areas unaffected by the fire.
“(The snowpack is burning) 80 percent to 140 percent faster than unburned sites near our study plots,” McGrath said. “Snow disappeared 11 to 13 days earlier in the burned landscape than in the unburned landscape.”
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Dillon Thomas of CBS News Colorado reported this recently CSU researchers found layers of dust blowing from the southwest corner of the state also caused faster melting. This dust is not caused by fires, but has a similar effect.
Like dust in snow, ash and other things left behind by wildfires also cause snow to melt faster on sunny days.
“Debris and tree stumps throw dark material and soot onto the snow surface, which changes the reflectance of the snowpack,” McGrath said.
The dark soot left behind by the fires causes light to be absorbed by the snow, causing faster melting. This means that not only does the snow melt faster, but less water is retained in the soil.
“That can affect seedling survival. So it also plays into how that landscape will regenerate and revegetate after the fire,” McGrath said.
McGrath says faster flooding likely won’t lead to greater flooding concerns in Colorado. However, this does not mean that the impacts of burn scars on the snowpack will remain limited to the state.
It is estimated that between 50% and 70% of the water resources of the western United States come from the Rocky Mountains.
“We’re already so stretched thin on our water resources,” McGrath said.
With massive burn scars causing earlier runoff, there is concern that water resources may be even more limited in late summer and early fall.
In addition to drinking water, Americans in the West depend on this same water to produce vegetables, fruits and more that end up in the stores of big cities like Las Vegas, Los Angeles and more.
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“So every year we see an increase in wildfires in the West, we’re compounding the impact across the region and increasingly affecting these essential water resources,” McGrath said.
McGrath says that for now, there are no clear ways that humans can directly solve this problem. Once the fires start and grow, the damage is done.
There are ways that Coloradans are working to prevent wildfires from growing.
The crews don’t just help clean up dead, dry debris in the summer and burn it into piles in the winter.. But crews are also working to conduct large controlled burns that will serve as a barrier in the event of future fires along the basin.
Other entities, many of which are operated by Colorado municipalities are stepping in to burn scars and try to remediate the impacts by leaving wood chips on parts of the burn scar along rivers.in an effort to try and get more water absorbed into the ground.
McGrath says the results of the CSU research should serve as a warning to the human race to take climate change more seriously and take steps to prevent wildfires that are becoming more frequent as a result of climate change.
“These impacts last much longer than the year of the fire,” McGrath said. “All citizens of the western United States will be directly affected by these fires occurring in this region.”
Dillon Thomas
