Warming rivers are melting Arctic sea ice, new study shows

(Photo provided by Lisa Hatland/USCG)

Warming rivers play an increasingly important role in melting sea ice and rising air temperatures in the Arctic, according to a new study published Nov. 6 in the journal Science Advances.

Using complex modeling techniques, a team of international researchers found that heat from rivers melted as much as 10% of Arctic sea ice between 1980 and 2015.

University of Alaska Fairbanks researcher Igor Polyakov is one of the study’s authors.

“Because of increase of surface area temperature over continents, the riverine water becomes warmer. This warmth is carried by river water into the Arctic,” he said.

The warmer river water then flows beneath sea ice, causing it to melt. That triggers a cycle where newly open ocean absorbs heat from the atmosphere, warming the ocean temperature even more and melting sea ice further.

“What we showed is that this positive feedback mechanism almost doubles the effect of original heat carried by rivers. So it’s multiplication of causes and effect in this system,” Polyakov said.

The Arctic is warming at almost twice the rate of the global average, and the impact of climate change there is well-documented. But the impact of river heat on sea ice loss and ocean and atmospheric temperatures is not. Polyakov said their research identified a previously overlooked piece.

“Our study is just one element of a big puzzle of Arctic or global climate change, but it’s an important element,” he said. “It creates a more complete, more interesting picture of multi-disciplinary changes in the Arctic in general.”

The effect is especially pronounced in places with larger rivers like Siberia and Canada’s Mackenzie River, but smaller rivers in Alaska play a role, too.

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