Rivers melt Arctic ice, warming air and ocean

Water from Canada’s Mackenzie River enters the blue Arctic Ocean in July 2012. White areas in the top half of the photo are largely sea ice, while those below are clouds over land.
Credit: NASA Earth Observatory

A new study shows that increased heat from Arctic rivers is melting sea ice in the Arctic Ocean and warming the atmosphere.

The study published this week in Science Advances was led by the Japan Agency for Marine-Earth Science and Technology, with contributing authors in the United States, United Arab Emirates, Finland and Canada.

According to the research, major Arctic rivers contribute significantly more heat to the Arctic Ocean than they did in 1980. River heat is responsible for up to 10% of the total sea ice loss that occurred from 1980 to 2015 over the shelf region of the Arctic Ocean. That melt is equivalent to about 120,000 square miles of 1-meter thick ice.

“If Alaska were covered by 1-meter thick ice, 20% of Alaska would be gone,” explained Igor Polyakov, co-author and oceanographer at the University of Alaska Fairbanks’ International Arctic Research Center and Finnish Meteorological Institute.

Rivers have the greatest impact during spring breakup. The warming water dumps into the ice-covered Arctic Ocean and spreads below the ice, decaying it. Once the sea ice melts, the  begins heating the atmosphere.

The research found that much more river heat energy enters the atmosphere than melts ice or heats the ocean. Since air is mobile, this means river heat can affect areas of the Arctic far from river deltas.

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