The relative warmth of northern Europe is related to substantial northward heat transport in the Atlantic. Heat is progressively lost to the overlying atmosphere and conveyed eastward with the prevailing winds. Cross-basin asymmetry in air temperatures is most extreme in wintertime, when temperatures across northwest Europe are 10–20°C higher than those in eastern Canada. Variability of ocean heat transport on timescales from interannual to multidecadal is consequential for regional climate in the North Atlantic, while decadal climate variability in the Pacific is linked to changes in tropical and subtropical ocean circulation. Ocean currents further influence climate via freshwater transports that influence dense water formation at high latitudes. Under a warming climate and an intensifying hydrological cycle, ocean currents convey salinity anomalies that could destabilize the circulation. Proxy evidence for abrupt cooling around the northern hemisphere indicates that this happened under glacial climate, when substantial surface freshening led to MOC collapse.
Ocean Currents, Physical Drivers in a Changing World, 2021, Pages 497-520,