Global Warming

Study: Melting ice sheets may cause ‘climate chaos’

Billions of tonnes of meltwater flowing into the world’s oceans from the Greenland and Antarctic ice sheets could boost extreme weather and destabilise regional climate within a matter of decades, researchers said yesterday.

These melting giants, especially the one atop Greenland, are poised to further weaken the ocean currents that move cold water south along the Atlantic Ocean floor while pushing tropical waters northward closer to the surface, they reported in the journal Nature.

Known as the Atlantic Meridional Overturning Circulation (Amoc), this liquid conveyor belt plays a crucial role in Earth’s climate system and helps ensures the relative warmth of the Northern Hemisphere.

“According to our models, this meltwater will cause significant disruptions to ocean currents and change levels of warming around the world,” said lead author Nicholas Golledge, an associate professor at the Antarctic Research Centre of New Zealand’s Victoria University of Wellington.

The Antarctic ice sheet’s loss of mass, meanwhile, traps warmer water below the surface, eroding glaciers from underneath in a vicious circle of accelerated melting that contributes to sea level rise.

Most studies on ice sheets have focused on how quickly they might shrink due to global warming, and how much global temperatures can rise before their disintegration — whether over centuries or millenia — becomes inevitable, a threshold known as a “tipping point.”

But far less research has been done on how the meltwater might affect the climate system itself.

One likely result of weakened current in the Atlantic will be warmer air temperatures in the high Arctic, eastern Canada and central America, and cooler temperatures over northwestern Europe and the North American eastern seaboard.