Changing wind patterns linked to global warming are altering the food chain in Antarctica and may lead to further increases in greenhouse gases in the atmosphere.
The most basic food, plankton, is declining in the northern portions of the Antarctic peninsula reaching toward South America, researchers report in Friday's edition of the journal Science.
At the same time, populations of Adelie penguins, which require a colder climate, have dropped sharply in that region, while warmer-weather chin-strap penguins have increased.
"We're showing for the first time that there is an ongoing change on phytoplankton concentration and composition along the western shelf of the Antarctic Peninsula that is associated with a long-term climate modification. Martin Montes-Hugo, a marine scientist at Rutgers University, said in a statement. "These phytoplankton changes may explain in part the observed decline of some penguin populations."
The change reflects shifting patterns of cloud cover, ice formation and winds, the report said.
"In the north, sea ice cover is minimum in recent times and is accompanied by a greater wind mixing of the water column and more cloudy days," Montes-Hugo said. "The increased mixing and increased cloudiness mean less light, which means less photosynthesis and less phytoplankton. What’s happening in the south is that there is less sea ice, but also less mixing and fewer clouds, which means more illuminated waters, more photosynthesis and more phytoplankton."
A separate report in the same edition of Science raises the possibility that new wind patterns could result in more upwelling of deep water in the region, which would then release stored carbon dioxide, potentially increasing global warming.
"The faster the ocean turns over, the more deep water rises to the surface to release CO2," said Robert Anderson, a geochemist at Columbia University's Lamont-Doherty Earth Observatory. "It's this rate of overturning that regulates CO2 in the atmosphere."