Antarctic ocean currents headed for collapse, say scientists

The fast melting of Antarctic ice threatens to slow deep currents in the world's oceans, adversely affecting the climate, the spread of fresh water and oxygen as well as life-sustaining nutrients for centuries, scientists have said.

According to a new study published in the journal Nature on Wednesday, deep water currents around Antarctica could slow by more than 40% in the next 30 years.

The "overturning circulation" of waters in the depths of the oceans would slow by 40% by 2050 in a high-emissions scenario, the study said, warning of repercussions that would last "for centuries to come."

New modeling cited in the study indicated rapid Antarctic ice melts driving a "substantial slowdown" of water circulation in the deepest parts of the oceans if global carbon emissions remain high.

'Headed to collapse'

If the model holds true, the deep ocean current will be "on a trajectory that looks headed towards collapse," said Matthew England, a climate professor at the University of New South Wales (UNSW), who coordinated the study.

Trillions of tons of cold, highly salty and oxygen-rich water sink around Antarctica every year, sending a deep-water current north to the Indian, Pacific and Atlantic oceans.

A higher volume of melting ice leads to the Antarctic waters becoming less dense and salty, slowing the deep-ocean circulation.

With the collapse of this deep ocean current, oceans below 4,000 meters would stagnate.

"This would trap nutrients in the deep ocean, reducing the nutrients available to support marine life near the ocean surface," England said.

The study also said that the melt of the Antarctic and Greenland ice sheets was expected to continue to accelerate as the earth warms.

"We are talking about the possible long-term extinction of an iconic water mass," England said.