Nordic Seas Cooled 500,000 Years Before Global Oceans

The cooling of Nordic Seas in northern Europe toward modern temperatures started 500,000 years before global oceans began cooling, according to a recent study at The University Of Bergen.

In their study, the researchers investigated the fossil remains of microscopic marine plankton, called dinoflagellate cysts, in two sediment cores from the Norwegian Sea and the Iceland Sea, according to a news release.

"We see that the dinoflagellate cyst assemblages underwent fundamental changes around 4.5 million years ago. Together with the simultaneous first occurrence of cool-water Pacific mollusks in Iceland, our results demonstrate that the Nordic Seas cooled significantly", said Stijn De Schepper, researcher of the study.

The world was much warmer 5.3 to 2.5 million years ago, according to the researchers. Oceans began cooling about 4 million years ago, but in this study the researchers found that Nordic Sea began cooling 500,000 years earlier. They found that the Bering Strait was open at this time, and cool water flowed along East Greenland and the Nordic Seas, which had the same temperature and circulation pattern as the modern world today.

Present day Nordic Sea surface waters are characterized by an east-west temperature gradient (incline). Southern parts of Greenland have the same latitude as Bergen and Oslo in Norway, however, the climate in Greenland is cooler, according to the researchers.

"Our study shows that a surface water temperature gradient was only established since 4.5 million years ago, when warm waters continued to flow along the Scandinavian coast and cool water entered the Nordic Seas along Greenland's east coast", said De Schepper. 

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