"In the Northern Hemisphere, much of the ground is permafrost, meaning it is frozen year-round. Permafrost is a delicate natural resource. If it is lost faster than it is regenerated, we endanger infrastructure and release carbon, which can warm the atmosphere," said Nathan D. Brown, assistant professor of earth and environmental sciences at UT Arlington. "Under a warming climate, a major question is whether arctic rivers will erode permafrost in thawing riverbanks faster than permafrost can regenerate."
Rivers naturally alter their courses over time due to factors such as floods, earthquakes, vegetation, and wildlife. These changes are typically gradual.
Alaskan rivers, however, face the unique challenge of permafrost, a mix of soil, gravel, sand, and ice, which is crucial for trapping large amounts of organic carbon. When permafrost melts, this carbon is released, forming carbon dioxide, a greenhouse gas that exacerbates global warming.
Dr. Brown and his team, including researchers from the California Institute of Technology, Massachusetts Institute of Technology, University of California at Santa Barbara, Los Alamos National Laboratory, the University of Chicago, and the University of Pennsylvania, studied the Koyukuk River in Alaska. They mapped and dated floodplain deposits, analyzed permafrost extent, and examined vegetation to model permafrost dynamics in relation to air temperature. The Koyukuk River, a 425-mile tributary of the Yukon River, plays a significant role in the region's hydrology before merging into the Bering Sea.
In their report published in the American Geophysical Union journal AGU Advances, the researchers found that while new permafrost is forming along the Koyukuk River floodplain, it is not developing quickly enough to compensate for the loss driven by rising temperatures.
"By dating these permafrost deposits, we found that permafrost formation in this region can take thousands of years," said Brown. "Under a warming climate, permafrost formation is expected to take longer, while thawing permafrost riverbanks will become more susceptible to erosion. The net result will be loss of permafrost and contribution of carbon to the atmosphere."
Research Report:Permafrost Formation in a Meandering River Floodplain
Related Links
University of Texas at Arlington
Beyond the Ice Age
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