Antarctic ice could have runaway melting if critical threshold crossed

• News & Highlights

Giant slabs of sea ice carving off of glaciers and crumbling into the sea could become a common sight if the climate continues to warm, warn scientists. The bleak outlook comes from a new study in which researchers claim that the Antarctic ice could shrink by 186 miles (300 km) if the climate change continues unabated. Such a huge loss of sea ice would result in global sea levels rising by almost three metres over the course of the next few centuries, they add.

An international group of scientists, comprising researchers from the UK, Australia, New Zealand and the US, made the predictions based on measurements of a huge glacier in the Antarctic. Totten Glacier drains one of the largest ice masses in the world, the East Antarctic Ice Sheet.

By studying how the glacier has grown and shrank over time, they found that it may be teetering on the edge of a critical threshold. Scientists say that if climate change continues on the ‘business as usual’ trajectory – without intervention – the glacier could cross this threshold sometime in the next century, leading to an irreversible melting on a massive scale and causing the glacier to retreat rapidly.

The evidence coming together is painting a picture of East Antarctica being much more vulnerable to a warming environment than we thought,’ said Professor Martin Siegert, co-director of the Grantham Institute at Imperial College London.

‘This is something we should worry about. Totten Glacier is losing ice now, and the warm ocean water that is causing this loss has the potential to also push the glacier back to an unstable place.’ According to the researchers, the glacier’s rapid retreat would cause it to withdraw up to 300 kilometres inland over the following centuries. The vast quantities of water locked up in the ice would be released, contributing as much as 2.9 metres to global sea-level rise.

Professor Siegert added: ‘Totten Glacier is only one outlet for the ice of the East Antarctic Ice Sheet, but it could have a huge impact.

'The East Antarctic Ice Sheet is by far the largest mass of ice on Earth, so any small changes have a big influence globally.’

The findings are published today in the journal Nature.