Climate Change Responsible for Slowdown of Chilly Ocean Currents in Antarctica
A new study declares that Antarctica's changing climate is responsible for shutdown of Antarctica Bottom Water. In past recent studies, researchers found shrinking of chilly salty ocean currents, the Antarctic Bottom Water, that flows from the underwater edge of the Antarctic continent north toward the equator.
These cold water currents carry oxygen, carbon and nutrients down to the deepest parts of the ocean. They also found less saline nature in the ocean surface off Antarctica's shore, which they declared is due to melting of glaciers and increase in precipitation.
Discovery of warm water in the Antarctic Ocean, in the Weddell Sea, has been declared as one of the most surprising discoveries of the 20th century. This type of area in which ice is surrounded by water is called polynya by geographers. They cited an example of disappearance of a huge ice-free region, typically of size of New Zealand, existing within the ice blanket of the southern ocean surrounding Antarctica.
Researchers said this drop in saline nature of water and increase in freshwater layers prevents formation of cold-water currents offshore the Antarctica. Casimir de Lavergne, oceanographer at McGill University in Montreal, said: "Deep ocean waters only mix directly to surface in few small regions of global ocean, so this has effectively shut one of main conduits for deep-ocean heat to escape".
The research published in the Journal Nature Climate Change reveals that freshwater acts like lid over the Antarctica's surface, closing the ocean circulation and thus preventing flow of cold water currents and increasing the warm water currents up to the mixing regions.
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