Observed water column temperature shift in the Barents Sea, 1970-2016. Graphic: Lind, et al., 2018 / Nature Climate Change

By Thomas Nilsen
5 July 2018

(The Barents Observer) – The northern Barents Sea is an Arctic warming hotspot, says Sigrid Lind with the Marine Research Institute in Tromsø, Norway. Changes go from Arctic to Atlantic climate, concludes a study Lind and other scientists have made. The results are published in a recent article in Nature.

The ocean researchers have used a compilation of hydrographic observations from 1970 to 2016, investigating the link between changing sea-ice import and the warming hotspot of the northern Barents Sea.

“A sharp increase in ocean temperature and salinity is apparent from the mid-2000s, which we show can be linked to a recent decline in sea-ice import and a corresponding loss in freshwater, leading to weakened ocean stratification, enhanced vertical mixing and increased upward fluxes of heat and salt that prevent sea-ice formation and increase ocean heat content,” Sigrid Lind tells in the article.

Thus, the northern Barents Sea may soon complete the transition from a cold Arctic to a warm and well-mixed Atlantic dominated climate regime. In fact, the entire Barents Sea will be ice-free year-around.

“Such a shift would have unknown consequences for the Barents Sea ecosystem,” Lind says.

What happens now due to climate changes is a self-reinforcing cycle. The climate tipping point for Arctic sea-ice might already been past, since the Barents Sea acts like a buffer between the Arctic Ocean and the North Atlantic. Warm Atlantic water will no longer be pressed deeper by freshwater around Svalbard because the fresh water floating south from sea-ice disappears, and with the saltier Atlantic water sea-ice formation will decrease. Sea-ice has been the most important source of fresh water to the northern Barents Sea.

The ocean researchers argue that ice-associated marine mammals and commercial fish stocks are at stake.

Norway’s Meteorological Institute has all summer published highly worrying ice maps for the Barents Sea. Though, better named “ice-free maps” when looking closer. The Wednesday, 4 July 2018, map of Svalbard shows the Hinlopen Strait with very little ice. Also, waters around the islands of Nordaustlandet, Kong Karls land, and Kvitøya have no sea-ice.

“This is the lowest area for this day of the year in our records dating back to 1967,” Norway Ice Service writes in a tweet.

“For the waters around Svalbard it is a record low ice area by a good margin,” says Nick Hughes, Leader of the Ice Service in Tromsø to the Barents Observer. [more]

Northern Barents Sea warms dramatically


Ocean heat content in the northern Barents Sea, observed during 1970–2016. Graphic: Lind, et al., 2018 / Nature Climate Change

ABSTRACT: The Arctic has warmed dramatically in recent decades, with greatest temperature increases observed in the northern Barents Sea. The warming signatures are not constrained to the atmosphere, but extend throughout the water column. Here, using a compilation of hydrographic observations from 1970 to 2016, we investigate the link between changing sea-ice import and this Arctic warming hotspot. A sharp increase in ocean temperature and salinity is apparent from the mid-2000s, which we show can be linked to a recent decline in sea-ice import and a corresponding loss in freshwater, leading to weakened ocean stratification, enhanced vertical mixing and increased upward fluxes of heat and salt that prevent sea-ice formation and increase ocean heat content. Thus, the northern Barents Sea may soon complete the transition from a cold and stratified Arctic to a warm and well-mixed Atlantic-dominated climate regime. Such a shift would have unknown consequences for the Barents Sea ecosystem, including ice-associated marine mammals and commercial fish stocks.

Arctic warming hotspot in the northern Barents Sea linked to declining sea-ice import

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