The Arctic Ocean Spices Up

The contemporary Arctic Ocean differs markedly from midlatitude, ice-free, and relatively warm oceans in the context of density-compensating temperature and salinity variations. These variations are invaluable tracers in the midlatitudes, revealing essential fundamental physical processes of the oceans, on scales from millimeters to thousands of kilometers. However, in the cold Arctic Ocean, temperature variations have little effect on density, and a measure of density-compensating variations in temperature and salinity (i.e., spiciness) is not appropriate. In general, temperature is simply a passive tracer, which implies that most of the heat transported in the Arctic Ocean relies entirely on the oceandynamics determinedby the salinity field. It is shown, however, that as theArcticOceanwarms up, temperature will take on a new role in setting dynamical balances. Under continued warming, there exists the possibility for a regime shift in themechanisms bywhich heat is transported in theArcticOcean. Thismay result in a cap on the storage of deep-ocean heat, having profound implications for future predictions of Arctic sea ice.