A large portion of the Arctic Ocean is rapidly shifting toward an Atlantic climate, a Norwegian study has found. Scientists fear the changes, occurring in the northern Barents Sea, may be too far along to reverse, which could impact Arctic ecosystems and weather phenomena across Europe and Asia.
Scientists at Norway’s Institute of Marine Research in Tromso and the University of Bergen published their results on Monday in the journal Nature Climate Change.
The northern Barents Sea lies to the north of Scandinavia and east of the remote Svalbard archipelago, an unincorporated area of Norway. The area – referred to by researchers as “the Arctic warming hot spot” – is one of the fastest-warming regions of the ocean in world. Since 2000, temperatures in the northern Barents Sea have risen by 2.7 degrees Fahrenheit, The Washington Post.
Waters in the Arctic Ocean are typically stratified – cold, fresher waters characteristic of an Arctic climate stay on top, while warmer, saltier waters originating from the Atlantic remain below. The layers, maintained by differences in density between the fresher and more saline waters, prevent heat from the warmer waters below from escaping into the atmosphere, reports The Washington Post.
The team based their analysis on ocean temperature and salinity data collected every year between 1970 and 2016. They also used satellite data from the National Snow and Ice Data Centre to examine changes in sea ice cover.
The data showed that a decreasing amount of sea ice in the northern Barents Sea is providing the area with less fresh water. As a result, warmer Atlantic waters extend higher towards the ocean’s surface, making the sea warmer and saltier.
“Less sea ice inflow from the interior Arctic has caused a 40% freshwater loss in the northern Barents Sea, leading to weaker stratification and increased vertical mixing with the deep Atlantic layer,” lead author Dr Sigrid Lind, from the Institute of Marine Research, said in a statement.
“Heat is brought up from the deep Atlantic layer, resulting in a dramatically warm Arctic layer,” Lind explained. “This can explain why the northern Barents Sea has become the hotspot of Arctic warming after the mid-2000s.”
Scientists warned in the study that if the freshwater input does not return to previous levels, “the entire region could soon have a warm and well-mixed water column structure and be part of the Atlantic domain,” noting that this would be “a historically rare moment.”
Lind told The Washington Post that the changes may be too far along to reverse: “What we show is the sea ice will probably move out of the Barents Sea completely and not come back,” she said.
If this were to occur, experts say it could impact Arctic marine ecosystems as well as weather patterns in Europe and Asia.
Jennifer Francis, an Arctic expert at Rutgers University, told The Washington Post that ice loss in the Barents Sea could affect the atmospheric jet stream, resulting in more extreme winter weather.
The changes could lead to “persistent cold spells over East Asia and a disrupted stratospheric polar vortex,” Francis said. “We saw this happen in spades this past winter.”