SOURCE: The Conversation
DATE: August 30, 2018
SNIP: The cold, remote Arctic Ocean and its surrounding marginal seas have experienced climate change at a rate not seen at lower latitudes. Warming air, land and sea temperatures, and large declines in seasonal Arctic sea ice cover are all symptoms of the changing Arctic climate. Although these changes are occurring in relatively remote locations, there is growing evidence to link Arctic sea ice retreat to increasingly erratic weather patterns over the northern hemisphere.
As sea ice declines, areas of open water increase, allowing the ocean to lose more heat to the atmosphere. Heat lost from the ocean to the atmosphere reduces the atmospheric pressure which provides more energy to storms and increases their cloud content through evaporation.
North of Svalbard, Atlantic Water heat has been mixed up towards the surface, resulting in increased surface heat lost to the atmosphere over the ever greater area of open ocean. This change has recently been shown to enhance the rate of sea ice loss eastwards.
In the Barents Sea, sea ice forms every autumn and melts in late spring/summer. In the northern part of the sea, a north-south change from cold to warm sea surface temperatures signals the presence of the Polar Front, which separates cold Arctic water from the warm Atlantic water. The meeting of the two water masses, its location and the temperature difference across it reflects changes in Barents Sea circulation.
During years with low seasonal sea ice concentrations (when there’s more heat loss from more exposed open water), the north-south differences in atmospheric temperatures across the Barents Sea are reduced. These conditions have been linked to wintertime cyclones travelling further south into western Europe, instead of their tendency to move eastwards towards Siberia, as well as more frequent cold winter extremes at middle latitudes.
Long-term oceanographic measurements of water temperature and salinity near the Barents Sea Opening have shown that inflowing Atlantic Water temperatures have increased over the last 30 years. An impact of the warmer water entering the Barents Sea is a warmer atmosphere, which in turn insulates the warmer surface water allowing the Atlantic Water heat to penetrate further to the north, preventing winter sea ice formation and import (that is sea ice that has formed farther north that has drifted southwards) to the region south of the Polar Front.