"We see that the convective process is shutting down as the water gets fresher and fresher," Marinov said.
Seven of the models suggest that increased fresh water in the Southern Ocean could stop the convection from occurring altogether by 2030, and most models show strong decreases in convection during the 21st century, reducing the Antarctic Bottom Waters' formation.
This has implications for current and future climate change, the researchers said. The absence of polynyas in recent decades could mean that heat is getting trapped in the deeper ocean, possibly contributing to the recent "hiatus" in global atmospheric warming and the increase in Antarctic sea ice extent that have been observed in recent years.
But overall, Marinov said, "the slow down of polynyas will likely be a positive feedback on warming, as the convective process is shutting down and reducing the amount of new, anthropogenic carbon and heat being taken out of the atmosphere. We are pursuing these implications in our current work."
In a related paper, published this month in the Journal of Climate, Bernardello, Marinov and colleagues examine how the ocean's natural ability to store carbon might respond as the climate warms.
The ocean contains about 50 times more carbon than the atmosphere, making it a crucial but sometimes overlooked player in climate change regulation.
This ability, Marinov noted, stems in large part because of tiny organisms called phytoplankton that live near the ocean's surface.
"They are all microscopic so we don't see them, but they are mighty," Marinov said. "They account for 50 percent of the photosynthesis that occurs on the planet."
In conducting photosynthesis, t
|Contact: Katherine Unger Baillie|
University of Pennsylvania