BBC Science Focus



Beavers are contributi­ng to permafrost decline

Alaskan beavers are contributi­ng to the decline of the Arctic permafrost at an ‘exponentia­l’ rate, a study carried out by researcher­s at the University of Alaska, Fairbanks has found. Permafrost is a layer of soil, rocks and ice that has remained frozen for at least two years. Permafrost locks up greenhouse gases, so if it degrades, methane and carbon can leach into the atmosphere. In the northern hemisphere, almost a quarter of land has permafrost underneath. Over the last few decades, researcher­s have noticed beaver population­s spreading to previously uninhabite­d regions of Alaska, creating dams and new lakes. As these bodies of water are warmer than the surroundin­g soil, it can cause the permafrost underneath them to thaw.

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