Scientists have issued new warnings over a glacier in Antarctica that is described as "the doomsday glacier" because its collapse could lead to rapid sea-level rise.

Even now, ice draining from Thwaites Glacier into the Amundsen Sea accounts for about 4% of global sea-level rise – but scientists fear it could collapse.

If it collapses it could raise sea levels about 65cm as it melts, and could also trigger a runaway collapse across the western half of Antarctica that could lead to a sea level rise of up to 6ft, scientists told the Financial Times.

Such a rise would be catastrophic for coastal cities around the world.

Paul Cutler, programme director for Antarctic glaciology at America’s National Science Foundation, said: "It is a keystone for the other glaciers around it in West Antarctica … If you remove it, other ice will potentially start draining into the ocean too."

Cutler said Thwaites Glacier is losing ice faster and faster, and that the process seems to be accelerating.

"The big question is how quickly it becomes unstable," he said. "It seems to be teetering at the edge."

Teams of scientists are drilling into Thwaites Glacier to find out if it’s about to collapse.

The glacier is 74,000 square miles, the size of Great Britain, and thought to be particularly susceptible to climate change.

Over the past 30 years, the amount of ice flowing out of Thwaites and its neighbouring glaciers has nearly doubled.

Rob Larter, UK principal investigator for the Thwaites Glacier Project at the British Antarctic Survey, told the FT: "It is the most vulnerable place in Antarctica."

The South Pole, the most remote place on the planet, has warmed three times faster than other areas over the past three decades, researchers say.

Research published in Nature Climate Change found an abrupt shift has seen temperatures rocket upwards at the pole since 1989.

Since that point, temperatures at the pole have risen 0.6 degrees per decade, three times the rate for the rest of the planet.

Researchers believe the high temperatures are being fuelled not just by a rise in greenhouse gases, but also by natural weather shifts in the tropics.

Record-breaking high temperatures are being fuelled by increases in greenhouse gases – and natural weather shifts in the tropics, say scientists.

The "double whammy" sheds light on why Antarctica is bearing the brunt of climate change.

Dr Kyle Clem of Victoria University of Wellington in New Zealand, said: "These trends were unlikely the result of natural climate change alone.

"The effects have likely worked in tandem to make this one of the strongest warming trends on Earth."