A new study says the Gulf Stream is now the weakest in more than 1,000 years, with major implications for future storms in Europe and sea-level rise along the east coast of the United States.
Some of the world’s leading experts studied the circulation patterns of the Atlantic Ocean, including the currents of the Gulf Stream flowing from south of Florida up to Greenland, and published their results in the journal Nature Geoscience. The circulation, they said, is now “in its weakest state in over a millennium.”
Their research showed that the current has slowed by 15 percent since 1950, and it could slow an additional 34 to 45 percent by the end of the century if global warming continues at its current pace.
The Gulf Stream moves a massive amount of warm water near the surface from the tropics up to the North Atlantic. When it reaches the Greenland area, it cools enough to become more dense and heavier and it sinks. That cold water is then carried southward in a deep water current.
Looking at records to reconstruct the past, the scientists found that climate change in the Northern Hemisphere can cause the water current to slow. This is particularly true when glacial ice melts and flows into the North Atlantic. Fresh water from the ice is not as salty, or as dense, as sea water, and it does not sink as fast. Too much fresh water means the stream loses momentum.
The research shows this is occurring now in Greenland, for example, where ice is melting at an accelerating pace.
The scientists were able to paint a picture of the past 1,600 years of water circulation in the North Atlantic. “The study results suggest that it has been relatively stable until the late 19th century,” said Stefan Rahmstorf, the author of the study and an oceanographer at the Potsdam Institute. “With the end of the little ice age in about 1850, the ocean currents began to decline, with a second, more drastic decline following since the mid-20th century.” Read more: