GOLDEN KNIFE –
Scientists have long believed that rapid warming in the Arctic would cause rivers to move faster, but a new study suggests the opposite may be true for large, winding rivers in area.
The paper, published in the scientific journal Nature and Climate Change, details how an international team of researchers tested the theory by analyzing satellite images of rivers in Alaska, the Yukon and the Northwest Territories over time.
They found that the migration rates of these rivers, instead of increasing, decreased overall by about 20 percent between 1972 and 2020.
“My reaction was ‘Wow, it’s hard to convince people of this,'” said Alessandro Ielpi, lead author of the study.
“It has the potential to be a groundbreaking idea. It has the potential to reshape the way we think about northern environments and how they adapt to climate change.”
Ielpi, an assistant professor in the Department of Earth, Environmental and Geographic Sciences at the University of British Columbia-Okanagan, says it is “almost a core belief” in the scientific community that rising temperatures and melting Permafrost will accelerate the rate at which rivers change position.
“Think of trying to dig a hole in frozen ground. Of course, you’ll use more energy and will require more work than digging or eroding unfrozen soil.” he explained.
“If the temperature rises and the frozen ground gradually melts, the opposite will decrease the resistance to erosion.”
Scientists have a theory as to why the migration of these rivers has slowed over the past five decades – mainly the process of Arctic greening.
While increasing temperatures and humidity in the Arctic have led to permafrost thawing, they have also resulted in shrubs growing thicker and taller in areas that were once barren or sparsely vegetated.
Ielpi said increased vegetation is making riverbanks more stable and less prone to erosion, and vegetation is reducing surface runoff by using water.
The study focused on 10 rivers that zigzag more than 100 meters across permafrost terrain, including the Mackenzie, Porcupine and Yukon rivers. Its authors caution that these findings may not apply to smaller streams in upland basins, as they may respond differently to increasing temperatures.
“More data from the ground and more studies will be needed in the coming years to corroborate this interpretation,” Ielpi said.
He said the findings underscore the need not to “take anything for granted and always look for the unexpected.”
They could also have implications for how Northern communities plan for the future, he said.
This report by The Canadian Press was first published on March 10, 2023.
This story was produced with the financial support of Meta and the Canadian Press News Scholarship.
