A Blue Spot on a Warming Earth

Environmental & Science Education

STEM

Climate Change

Earth Systems

Earth Science

Edward Hessler

The North Atlantic Current (NAC, also known as the North Atlantic Drift) is one of the great currents in the circulation of the global oceans. It extends the Gulf Stream (aka the thermohaline circulation) northeastward toward Europe. 

The future of the NAC has been the subject of considerable concern since it serves as a conveyor belt in distributing the ocean's waters, heat and nutrients. According to Stefan Rahmstorf (University of Potsdam) the NAC "keeps Northern Europe several degrees warmer than it would otherwise be at this latitude."

A Yale Climate Connections video reviews the concerns. Climatologist Michael Mann of Pennsylvania State University notes that a "stubborn blue spot of cool ocean temperatures stands out like the proverbial sore thumb in a recent NASA image of the warming world--a circle of cool blue on a planet increasingly shaded in hot red."

Is this blue spot "an indication that the NAC...is slowing down?" 

The current is driven by a salt water pump. How it works is explained by Jorgan Peder Steffenson of the University of Copenhagen. "As the Greenland ice sheet melts large volumes of fresh water enter the North Atlantic and freshen the very salty sea water slowing the 'pump'."

Ominously, Mann states,“We are fifty to a hundred years ahead of schedule with the slowdown of this ocean circulation pattern, relative to the models.”