It is no mystery that sea levels have been rising, but scientists have recently identified another change: Ocean currents are speeding up. According to a study in Science Advances, this acceleration has been occurring since the 1990s, with the energy of currents increasing by approximately 15% per decade, and accelerating winds are the culprit.
According to multiple studies, wind speeds over the ocean are increasing, and since winds are one of the main forces behind ocean circulation, currents are speeding up as a result. Accelerating winds are also responsible for bigger ocean waves in parts of the world. While the exact reason for this change is not confirmed, scientists suspect that it is caused by global warming and natural climate variations, and models suggest that global warming will continue to strengthen winds, which will speed ocean currents further.
The study suggests that ocean currents are accelerating most notably in the tropics and other parts of the Atlantic, Indian and Pacific oceans. Currents in other parts of the ocean, however, are slowing, especially the Atlantic Meridional Overturning Circulation, which runs from the equator to the Arctic and has a large impact on weather patterns in the Northern Hemisphere. Scientists believe that climate change is responsible for this change as well, suggesting that melting sheet ice in Greenland is partially to blame. As a global average, however, currents are increasing.
Previous climate models had predicted that global warming would cause greater wind speeds around 2100, but the change has occurred much earlier than expected, and the study indicates that the earth may be more sensitive to warming than models have indicated. Accelerating ocean circulation may alter global weather patterns and marine ecosystems according to lead study author Shijian Hu, a scientist at the Chinese Academy of Sciences. Read more about the study here.