This article was originally featured on High Country News.
Chunks of carbon-rich frozen soil, or permafrost, undergird much of the Arctic tundra. This perpetually frozen layer sequesters carbon from the atmosphere, sometimes storing it for tens of thousands of years beneath the boggy ground.
The frozen soil is insulated by a cool wet blanket of plant litter, moss and peat. But if that blanket is incinerated by a tundra wildfire, the permafrost becomes vulnerable to thawing. And when permafrost thaws, it releases the ancient carbon, which microbes in the soil then convert into methane — a potent greenhouse gas whose release contributes to climate change and the radical reshaping of Northern latitudes across the globe.
Research published last month in Environmental Research Letters, a scientific journal, found that methane hot spots on the tundra are more likely to be found in places where wildfires burned recently. The study focused on Alaska’s largest river delta, the Yukon-Kuskokwim, an area previously identified as emitting large amounts of methane.
A team of scientists with NASA’s ABoVE project (Arctic-Boreal Vulnerability Experiment), which studies environmental change in Alaska and Western Canada, were curious about the cause of those methane hot spots, which were observed using aerial surveys in 2018. So lead author Elizabeth Yoseph, an intern at the time, overlaid maps of those areas with recent fire activity.
Her team found that the hot spots were almost 30 percent more likely to occur in areas that had experienced wildfire in the last 50 years than in unburned areas, a likelihood that jumped to nearly 90% if the fire’s perimeters touched water. Recently burned wetlands with especially carbon-rich soil had the highest ratio of hot spots. “Fires are an important influence on increasing emissions,” Yoseph said.
The large-scale findings, which cover almost 700 square miles in Alaska, help complement field…
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