LONDON - Many climate scientists regard Thwaites glacier in West Antarctica as one of the most vulnerable and most significant glaciers in the world in terms of future global sea-level rise.

Its collapse would raise global sea levels by more than half a metre on its own, and subsequently release other major bodies of ice in West Antarctica, which together could raise sea levels by 2-3 metres. The ramifications for many countries, including most of the world’s coastal cities, would be catastrophic.

For this reason, Thwaites is known as Antarctica’s “Doomsday glacier”.

Earlier this year a team of scientists observed, for the first time, the presence of warm water at a vital point underneath the glacier, which helps explain the reason behind the extent of its decrease.

The Thwaites glacier is 74,000 square miles, roughly the size of the UK. The ice melt draining from Thwaites into the Amundsen Sea already accounts for 4 per cent of global sea-level rise but scientists are concerned its continued existence is hanging in the balance as the world warms.

“The big question is how quickly it becomes unstable. It seems to be teetering at the edge,” Paul Cutler, programme director for Antarctic glaciology at America’s National Science Foundation told the Financial Times this week.

Antarctica accounts for vast quantities of ice – around 90 per cent of all ice in the world - and unlike in the Arctic, most of the ice is out of the water and on land. The average thickness of the ice is 1.6 miles deep. At its thickest point, the ice sheet is almost three miles deep.

Current sea level is around 20cm (almost 8 inches) above pre-industrial levels and is blamed for increased coastal flooding. The annual rate of sea-level rise has roughly doubled since 1990.