Permafrost isn't just a feature of the Arctic landscape — it actually shapes that landscape by directing water flow. As global temperatures rise, this permanently frozen ground could give way to the creation of new rivers and the expansion of existing ones, which would release huge amounts of carbon into the atmosphere, potentially setting off a destructive feedback loop, scientists said.
In a new study published in February. 1 in the newspaper With peopleScientists have looked into the role permafrost plays in the Arctic's watersheds, the area of land that transports water, such as rain and snowmelt, into creeks, streams, rivers, and eventually into reservoirs and oceans.
After analyzing data from more than 69,000 watersheds across the Northern Hemisphere, researchers discovered that the hard surface of permafrost prevents water from carving out channels — as it does in warmer landscapes — leading to fewer rivers in the region.
“When the ground is frozen, the water doesn't have enough force to sculpt through that frozen ground,” the study's first author, Joan Marie Del Vecchio, a researcher at Dartmouth University, told Live Science. This creates a smoothing effect, so hills rather than canals dominate the Arctic landscape.
Instead, the water flows over the permafrost in small paths called “water trails,” until it eventually reaches one of the few rivers in the Arctic.
The researchers found that these few Arctic rivers were deeper and steeper than those in temperate regions, occupying about 20% less area of the total landscape. They found that the Arctic watersheds were all formed by permafrost.
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However, as climate change takes hold, warming conditions will cause permafrost to thaw, adding more water to the landscape as snow melts earlier and precipitation falls as rain instead of snow. As the permafrost thaws, the soil will lose its “protective shield,” leading to erosion, Del Vecchio said.
“All of a sudden we have more water with more soluble soil, and that water may have the ability to sculpt,” Del Vecchio said. This could cause Arctic rivers to spread and grow, as well as add new rivers to the landscape, accelerating the disintegration of permafrost.
This shift in the Arctic landscape could have a major impact on global warming. This is because permafrost prevents the carbon stored within it from entering the atmosphere, but if the permafrost melts, carbon will be released, creating a feedback loop that will contribute to further global warming.
The study found that thawing permafrost due to a 1 degree Celsius (1.8 degree Fahrenheit) temperature rise in the Arctic could emit the same amount of carbon as 35 million cars driven for a year.
Erosion of thawed permafrost will lead to “more greenhouse gases, more warming, more dismantling of the landscape,” Del Vecchio said.
