After it loses heat in the Barents sea the warm salty Atlantic water becomes denser than the cold Arctic surface water which is freshened by the huge volume of river water that flows into the Arctic ocean. The Atlantic water forms a warm layer typically found beginning at about 200 meters deep in the Arctic ocean. The increased storminess in the Barents sea is apparently increasing the rate of flow of Atlantic water into the Siberian Basins of the Arctic, changing the Arctic currents and the distribution of salty and fresh water in the Arctic ocean.

Taken as a whole, the salinity of the Arctic Ocean is similar to the past, but the change in the freshwater pathway means the Eurasian Basin has gotten more saline while the Canada Basin has gotten fresher.“The freshening on the Canadian side of the Arctic over the last few years represents a redistribution of freshwater, there does not seem to be a net freshening of the ocean,” Kwok said.

In the Eurasian Basin, the change means less freshwater enters the layer known as the cold halocline and could be contributing to declines in ice in that part of the Arctic, Morison said. The cold halocline normally sits like a barrier between ice and warm water that comes into the Arctic from the Atlantic Ocean. Without salt the icy cold freshwater is lighter, which is why it is able to float over the warm water.

The increasing salinity of the surface water along the Siberian shelf is increasing its density. When ice forms in the winter the exclusion of salt from the ice is making water that is cold and dense enough to sink into the warm salty Atlantic water below. This increased mixing of warm water is heating the Siberian side of the Arctic ocean and the air above it. The following summer, it is leading to faster ice melt, furthering the death spiral of summer Arctic sea ice.