A subpolar gyre is a large-scale ocean current system located at high latitudes created by a persistent region of low atmospheric pressure. These gyres circulate water in a cyclonic direction – counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. This circular motion of water drives the upwelling of cold, nutrient-rich deep water to the surface, which plays an important role in regulating the climate in the higher latitudes as well as the nutrient cycles that sustain ocean ecosystems. Subpolar gyres influence the circulation of other ocean currents like the North Atlantic Current, the East Greenland Current, and the Labrador Current.
A new study by researchers at the University of Exeter in the UK examined changes in the ocean south of Greenland during the last 150 years and found that the inflow of freshwater has been disrupting the subpolar gyre since the 1950s. The research is yet another sign that climate heating caused mainly by fossil fuel pollution is pushing the climate towards dangerous tipping points.
A weakening or shutdown of the subpolar gyre and associated currents would weaken the northward transport of ocean heat from the tropics to higher latitudes. As a result, the tropics would experience more extreme heat on land and even worse ocean heatwaves than those that are already decimating marine organisms. Meanwhile, there would be regional cooling in the North Atlantic and more extreme weather in Europe: hotter summers, colder winters, and worse flooding and droughts, as wells as changes in global precipitation patterns. Disruption of ocean currents is a big problem and it is already happening.
