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Small rivers tell the story of thawing permafrost

13 March 2024
What effect does climate change have on Arctic permafrost? Earth scientist Niek Speetjens conducted research in Canada and discovered that the small river systems provide a lot of insight into the thaw of permafrost.

Permafrost, permanently frozen soil, is thawing due to climate change. This has consequences for water and carbon transport through river systems that flow into the sea from areas with permafrost. Earth scientist Niek Speetjens examined ice wedge polygon tundra (video), in an area along the coast of the Canadian province of Yukon, next to Alaska. This is a common landscape type in low-lying Arctic areas, such as Siberia. His research contributes to a better understanding of the changing Arctic carbon and water cycle and its impact on the rest of the world.

Small rivers
Due to its typical landforms, ice wedge polygon tundra normally retains water in the landscape and stores carbon in the form of plant residues. As temperatures warm, the ice wedges disappear, water flows away and carbon that was previously stored in the permafrost is released. Speetjens and his colleagues investigated this effect in small rivers in the Canadian Arctic. They mapped this process in a model, with which they can also make predictions on a larger scale.

In addition, they developed a database that maps all small river systems, looking at (permafrost) landscape types, soil properties and climate change. That database shows that the average temperature increase and carbon stock is greater than what you would expect if you only looked at the largest Arctic river systems, which has often been the case until now.

“My research shows that major changes are already underway in the Arctic,” says Speetjens. “To understand these changes, it is necessary that small-scale processes and the variation therein are better represented in climate forecasts. By better mapping the thaw of permafrost, better strategies can be developed to adapt to unwanted changes."

Speetjens will defend his dissertation on this topic on 20 March. Read more in his PhD thesis 'Arteries of a Changing Arctic: Small Rivers on a Global Scale'.

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