New research suggests that massive, rotating currents found in the world’s oceans are moving and scientists believe it could be due to climate change.
The enormous, swirling gyres are found in the North and South Pacific, the North and South Atlantic and the Indian Ocean. The currents, some of the biggest in the world, help transport heat and nutrients around the globe.
A new study by scientists from the Alfred Wegener Institute in Germany and the Ocean University of China appears to show the position of the gyres moving steadily toward the poles. Researchers say the phenomenon has been going on since the 1980s at a rate of about a half mile each year.
The researchers believe the shifting of the gyres has had an impact on raising sea levels in the mid-latitudes, including along much of the US East Coast. It had previously been thought that sea level rises in this region were the result of localized warming patterns and related changes in the structure of the ocean.
Their slow migration may also be a causal factor in recently observed changes in the movement of hurricanes poleward and the behavior of major atmospheric currents like the jet streams.
Although no exact cause has been found for the migration, the new study suggests climate change is playing some role. The researchers ran climate model simulations of satellite data on sea surface heights and temperatures – two variables that can be used to identify the gyres – from the 1980s up to the present. One set of simulations included historic data on greenhouse gas emissions and the other did not, implying a world without climate change.
For the simulations that included climate change data, the ocean gyres crept toward the poles, just as they do in the satellite record, suggesting that climate change has had some hand in the phenomenon.