SYDNEY, May 11 (Xinhua) -- A rapid decline in Antarctic sea ice since 2015 has been driven by "a cascade of ocean and atmospheric changes" that could accelerate global warming, new research has revealed.
The study found a "triple whammy" of interacting climate processes tipped the Southern Ocean into a new state, which triggered a sudden and dramatic decline in Antarctic sea ice after 2015, said a statement from Australia's University of New South Wales (UNSW) released Monday.
Greenhouse gases and ozone depletion strengthened Antarctic winds, drawing warm, salty water to the surface and releasing heat, triggering a feedback loop that keeps sea ice in a prolonged low state, said Aditya Narayanan, a visiting research fellow at UNSW Sydney.
Antarctica may now be shifting its state from a buffer against global warming to an amplifier of it, said Narayana, lead author of the study published in Science Advances.
Antarctic sea ice helps "drive the planet's ocean overturning circulation," moving warm surface water poleward and sinking cold, dense water that regulates Earth's climate, he said, adding that sea ice supports a highly productive ecosystem, from algae to krill, whales and penguins.
"What started as a slow build-up of deep-sea heat under the Antarctic sea ice was followed by a strong mixing of water, ending in a vicious feedback cycle where it's too warm to let ice recover," Narayanan said.
The Southern Ocean's layers, with cold, relatively fresh water sitting on top of warmer, saltier water below, act as a lid, trapping heat at depth, but this barrier has weakened, the research showed.
Using data and modeling, the team found that warm "Circumpolar Deep Water" rising closer to the surface, melting sea ice and destabilizing the world's ocean current systems, warming the planet far quicker than expected. ■
