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North Atlantic Warm Pool as a Signal of Gulf Stream Slowdown

Over the past few years we’ve seen very warm sea surface temperatures in the Gulf Stream off the U.S. East Coast. This heat traffic jam is an indicator of reduced energy transfer into the North Atlantic. In other words, there’s a strong observational signal that the Gulf Stream is slowing down.

(A much warmer than normal pool of water off the U.S. East Coast juxtaposed to an intense cool pool south of Greenland is a climate indicator of Gulf Stream slowdown.)

The development of a cool pool near Greenland, and associated with Greenland melt, is a further indicator of this trend. Recently, the near East Coast warm pool has enlarged and intensified. Meanwhile, the strength of the Greenland cool pool has also increased even as cold water currents issuing from Greenland appear to have sped up.

As noted above, Greenland melt is a major apparent driver. As glaciers speed up and calve more and more ice bergs, more fresh water enters the region around Greenland. This fresh water acts as a lens which cools off the ocean surface. It also serves as a cap, pushing down-welling water further south.

(Floods of ice bergs from melting Greenland glaciers like Jacobshavn have the potential to produce a climate and ocean circulation train wreck in the North Atlantic. Some indicators show that we are in the early stages of this disruptive process. Image source: NASA Worldview.)

The net effect is that the North Atlantic Ocean Conveyor acts as if a great wrench has been thrown into the works. The region around Greenland cools as areas further south heat up. A scenario that is also likely to generate more intense storms across the North Atlantic and over adjacent lands in Europe, North America and Greenland.

Recent scientific studies indicate that the North Atlantic circulation has slowed down by about 15 percent on decadal time scales. And it appears that this slow-down is showing up clearly in the North Atlantic sea surface temperature profile.

(A severe dipole anomaly for sea surface temperatures has developed in the North Atlantic. This is an observational indicator that Greenland melt is impacting North Atlantic Ocean circulation. Image source: Earth Nullschool.)

The combined indicators point toward serious systemic changes taking place in the region of the North Atlantic. Changes that are having knock-on effects to local climates — like enhancing the deepness of troughs over Eastern North America and lending higher atmospheric potentials that spike storm intensity. Meanwhile, considerable ocean conveyor slow-down risks a serious degradation of global ocean health.

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