In a recent paper, scientists expressed their surprise that the Arctic had started warming already back in the early 20th century, 100 years ago. This, along with the obligatory CO2 climate warming lip service, is described in a Cambridge University press release.
Hat-tip: Die kalte Sonne
An international group of researchers reconstructed the recent history of ocean warming at the gateway to the Arctic Ocean in a region called the Fram Strait, between Greenland and Svalbard, and found that the Arctic Ocean has been warming for much longer than earlier records have suggested.
Natural oceanic currents
The Arctic Ocean has been getting warmer since the beginning of the 20th century—decades earlier than records suggest—due to warmer water flowing into the delicate polar ecosystem from the Atlantic Ocean.
Atlantic waters flow into the Arctic
Using the chemical signatures found 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 preceeded the warming documented by modern instrumental measurements. Since 1900, the ocean temperature has risen by approximately 2 degrees Celsius, while sea ice has retreated and salinity has increased.
The results, reported in the journal Science Advances, provide the first historical perspective on Atlantification of the Arctic Ocean and reveal a connection with the North Atlantic that is much stronger than previously thought. The connection is capable of shaping Arctic climate variability, which could have important implications for sea-ice retreat and global sea level rise as the polar ice sheets continue to melt.
Atlantification is one of the causes of warming in the Arctic, however instrumental records capable of monitoring this process, such as satellites, only go back about 40 years.