Faster ocean currents linked to warmer ocean
San Diego researchers say warming ocean waters are gradually, but steadily, speeding up surface ocean currents and that could disrupt the ocean’s delicate food web.
“We were surprised to see that surface currents speed up in more than three-fourths of the world’s oceans when we heated the ocean surface,” said study lead author Qihua Peng, a postdoctoral researcher at the Scripps Institution of Oceanography.
Peng and Scripps Institution of Oceanography researcher Shang-Ping Xie were part of an international team, which included scientists in China and at the Woods Hole Oceanographic Institution in Massachusetts, that used computer climate models to track the speed of ocean currents.
Xie was surprised to find that warming ocean waters, not just winds near the ocean surface, are gradually increasing the speed of ocean currents.
“The upper ocean has a lot of sunlight, receive(s) a lot of sunlight, so it's conducive to photosynthesis,” said Shang-Ping Xie. “But in order for marine biology to thrive, the ocean has to supply the nutrients.”
Warmer temperatures near the surface are thinning the top layer of the ocean, which generates the most life.
“The warm water is floating on cold water so this is going to increase the contrast between warm water near the surface and cold water beneath,” Xie said.
The resulting separation reduces upwelling, which is the ocean’s way of mixing the surface and deep waters to feed marine life.
When the small microscopic marine life gets more scarce, larger fish and other food sources also become less common.
The swifter moving surface currents could also intensify storms over the ocean.
The findings are published in the April 20 edition of the journal Science Advances.