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Permafrost alone holds back Arctic rivers--and a lot of carbon
https://phys.org/news/2024-02-permafrost-arctic-rivers-lot-carbon.htmlNew research from Dartmouth College provides the first evidence that the Arctic's frozen soil is the dominant force shaping Earth's northernmost rivers. Permafrost, the thick layer of soil that stays frozen for two or more years at a time, is the reason that Arctic rivers are uniformly confined to smaller areas and shallower valleys than rivers to the south, according to a study in the Proceedings of the National Academy of Sciences.
But permafrost also is an increasingly fragile reservoir of vast amounts of carbon. As climate change weakens Artic permafrost, the researchers calculate that every 1.8 degrees Fahrenheit (1 degree Celsius) of global warming could release as much carbon as 35 million cars emit in a year as polar waterways expand and churn up the thawing soil.
"The whole surface of the Earth is in a tug of a war between processes such as hillslopes that smooth the landscape and forces like rivers that carve them up," said first author Joanmarie Del Vecchio, who led the study as a Neukom Postdoctoral Fellow at Dartmouth with her advisers and study co-authors Marisa Palucis, an assistant professor of earth sciences, and engineering professor Colin Meyer.
"We understand the physics on a fundamental level, but when things start freezing and thawing, it's hard to predict which side is going to win," Del Vecchio said. "If hillslopes win, they're going to bury all that carbon trapped in the soil. But if things get warm and suddenly river channels start to win, we're going to see a large amount of carbon get released into the atmosphere. That will likely create this warming feedback loop that leads to the release of more greenhouse gases."
But permafrost also is an increasingly fragile reservoir of vast amounts of carbon. As climate change weakens Artic permafrost, the researchers calculate that every 1.8 degrees Fahrenheit (1 degree Celsius) of global warming could release as much carbon as 35 million cars emit in a year as polar waterways expand and churn up the thawing soil.
"The whole surface of the Earth is in a tug of a war between processes such as hillslopes that smooth the landscape and forces like rivers that carve them up," said first author Joanmarie Del Vecchio, who led the study as a Neukom Postdoctoral Fellow at Dartmouth with her advisers and study co-authors Marisa Palucis, an assistant professor of earth sciences, and engineering professor Colin Meyer.
"We understand the physics on a fundamental level, but when things start freezing and thawing, it's hard to predict which side is going to win," Del Vecchio said. "If hillslopes win, they're going to bury all that carbon trapped in the soil. But if things get warm and suddenly river channels start to win, we're going to see a large amount of carbon get released into the atmosphere. That will likely create this warming feedback loop that leads to the release of more greenhouse gases."