In a new study lead by Jonathan Bamber, scientists found that, over the past few decades, the melting of Greenland glaciers has been feeding an anomalous spike in North Atlantic freshwater. If it continues as it has been, in the coming years the spike will rival the effects of the Great Salinity Anomaly—a bulge of fresh water that can affect the circulation patterns of the whole Atlantic Ocean.
Here’s the background: In the late 1960s, the first Great Salinity Anomaly (GSA) formed off the eastern shores of Greenland. Formed by a spike in Arctic ice melt, the event led to the formation of a thin sheet of fresh water that floated on the typically cold, salty waters of the north Atlantic Ocean. Over the subsequent years, the anomaly drifted about the North Atlantic, first around the southern tip of Greenland, then off to the coast of Canada, then up and around, along the Gulf Stream to northern Europe. As it traveled, the freshwater pool acted as a cap, limiting the interaction between the air and the ocean.
According to Oceanus, the magazine of the Woods Hole Oceanographic Institution, “he GSA acted as a sort of moving blanket, insulating different parts of the deep ocean from contact with the atmosphere as it moved around the gyre.” Similar events have happened in the decades that followed, and scientists have found that they can cause unusual temperature patterns for the United States and northern Europe, and may even affect fish populations.
In the new study, researchers found found that the flow of fresh water from Greenland into the North Atlantic has been increasing since the 1990s. According to Michael Marshall for New Scientist, the melting Greenland ice could even make it so that the Atlantic Ocean is less able to draw carbon dioxide out of the atmosphere, creating the potential for a feedback loop that would further drive global warming.
The polar oceans are among the world’s most important carbon sinks, taking in carbon dioxide from the air and trapping it in their depths – and that could change as a result of the freshwater flux. Curry says Greenland’s fresh water will remain at the surface, since the weakened will be slow to carry it to the bottom. That also means that once this fresh water has absorbed as much carbon dioxide as it can hold, it will not be replaced at the surface by carbon-dioxide-free water that could absorb more of the gas.
More from Smithsonian.com:
Why 97 Percent Of Greenland’s Icy Surface Just Melted