The Arctic Ocean has been getting warmer since the beginning of the 20th century. That is decades earlier than records suggest due to warmer water flowing into the delicate polar ecosystem from the Atlantic Ocean.An international group of researchers reconstructed the recent history of ocean warming at the gateway to the Arctic Ocean in the Fram Strait region, between Greenland and Svalbard. Since 1900, the ocean temperature has risen by approximately 2 degrees Celsius, while sea ice has retreated and salinity has increased
The found chemical signatures in marine microorganisms. The researchers found that the Arctic Ocean began warming rapidly at the beginning of the last century as warmer and saltier waters flowed in from the Atlantic – a phenomenon called Atlantification – and that this change likely preceded the warming documented by modern instrumental measurements.
The researchers used geochemical and ecological data from ocean sediments to reconstruct the change in water column properties over the past 800 years. They precisely dated deposits utilizing a combination of methods and looked for diagnostic signs of Atlantification, like change in temperature and salinity.