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- This is the first research article that links the regional wind with the cross-shelf exchange of Atlantic Water on the northern Barents Sea shelf, says oceanographer Sigrid Lind. (Photo: Gunnar Sætra)
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The Barents Sea warms up from behind

A recent study by the Institute of Marine Research, the University of Bergen and the Bjerknes Centre for Climate Research in Norway shows that the northwest Barents Sea warmed substantially during the last decades. The temperature of the subsurface Atlantic Water in the northern Barents Sea increased rapidly during the late 1990s.

This was partly caused by the general warming of Atlantic Water in the North Atlantic Ocean. Additionally, a regional wind pattern indirectly strengthened a warm deep current that enters the Barents Sea from the north.

Protects ice cover

The warm deep current enters the Barents Sea from the Arctic Ocean. It flows into the Barents Sea below colder and fresher upper waters. The current is a branch of the Arctic Ocean Boundary Current that carries warm Atlantic Water below the cold surface waters through the Arctic Ocean. The branch enters the Barents Sea between Svalbard and Franz Josef Land. It carries warm Atlantic Water far into the Barents Sea. On its path through the northern Barents Sea the Atlantic Water gradually mixes with the cold waters above, such that the cold waters are warmed from below. The cold waters protect the ice cover on the surface from the warm Atlantic Water below. And more importantly, the cold waters protect the ice cover from the massive amount of even warmer Atlantic Water south of the ice edge.

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A warm deep current enters the Barents Sea from the north. The current is a branch of the Arctic Ocean Boundary Current. The branch enters the Barents Sea below the ice cover and the colder and fresher upper waters (shown in blue).

Wind affects

The study argues that easterly winds along the Barents Sea shelf-slope will lead to a lift of the Arctic Ocean Boundary Current. This will increase the inflow of Atlantic Water to the Barents Sea. The study also shows that the regional wind pattern was favourable for easterly winds and increased inflow during the late 1990s and early 2000s. The easterly wind is part of the dipole pattern of near surface atmospheric pressure in the Arctic that was an unusual feature during this period. This is the first research article that links the regional wind with the cross-shelf exchange of Atlantic Water on the northern Barents Sea shelf.

Large impacts

The cold waters in the northern Barents Sea maintain a front against warmer and heavier water further south in the Barents Sea (the Polar Front). The Polar Front hinders the warm water further south from flowing into the northern Barents Sea. If the warm water could cross the Polar Front, the seasonal ice cover would not develop in winter. Thus the cold waters protect the seasonal ice cover of the Barents Sea. The warm Atlantic Water coming into the Barents Sea from the north may become a large threat to the ice cover. The Atlantic Water is not only warm, but also very saline. Thus, increased inflow of Atlantic Water from the north will increase the salinity and density of the cold upper waters. This will reduce the strength of the Polar Front; the warm water further south will start to cross the Polar Front; and the ice extent will be reduced. A substantial reduction of the ice cover will have large impact on the ecosystem, fisheries management, petroleum activity and shipping in the Barents Sea.

Barents Sea Facts

Russian name: Barentsevo More
Size: 1.4 million km2 in surface area (approximately four times as large as Norway).
Depth: Average depth = 230 m, Maximum depth = 500 m
Fisheries: Bottom fish such as cod, haddock, Greenland halibut, long rough dab, and redfish. Other commercially important species include: capelin; northern shrimp; minke whales, and harp seals
Special features:

  • Large annual variations in temperature relative to ice coverage
  • A shallow sea which makes up a portion of the continental shelf around the Arctic Ocean
  • Has one of the largest concentrations of sea birds in the world: approximately 20 million individuals distributed across 40 different species
  • Management of living marine resources in the Barents Sea is carried out through collaboration between Norway and Russia.
The Barent Sea Ecosystem

Contact

Sigrid Lind
482 18 555
Randi Ingvaldsen
951 29 885