The Arctic Ocean began warming years before previously documented, new research shows—a finding that has scientists concerned about the accuracy of their models. The study showed the water temperature in parts of the polar region have risen about 2 degrees Celsius since 1900, as warmer and saltier water from the Atlantic flowed in. Researchers call it "Atlantification," CNN reports. More work will be necessary to determine whether human-caused climate change played a role, said Francesco Muschitiello of the University of Cambridge, one of the study's authors.
By the time the 20th century dawned, "we've already been supercharging the atmosphere with carbon dioxide," Muschitiello said. "It is possible that the Arctic Ocean is more sensitive to greenhouse gases than previously thought." It's also possible that the system of currents that moderates temperatures in the Northern Hemisphere was a cause. The system became weaker after a cooling in the mid-19th century, which could have sparked the quick Atlantification, experts said. Ocean temperature and salinity didn't change much until the early 1900s.
Now scientists are questioning their processes. "The climate models that we use to cast projections of future climate change do not really simulate these type of changes," Muschitiello said. That means "there's an incomplete understanding of the mechanisms driving Atlantification," said Tesi Tommaso, another author, the university wrote in Phys.org. "The lack of any signs of an early warming in the Arctic Ocean is a missing piece of the puzzle," Tommaso added. The study was published Wednesday in Science Advances. (The two oceans are becoming more similar, another study found.)
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