New research shows that affected areas are losing ice five times faster than in the 1990s, more than 100m thick in places.
As a new analysis of satellite data shows, ice losses are spreading rapidly into the interior of Antarctica.
The warming of the Southern Ocean is causing glaciers to slide into the sea faster and faster, and ice is now being lost five times faster than in the 1990s. The West Antarctic ice sheet was stable in 1992, but up to a quarter of its extent is shrinking. More than 100 meters of thickness of ice have been lost in the worst affected places.
A complete loss of the West Antarctic ice sheet would raise sea levels to about five meters, drowning coastal cities around the world. Current losses are doubling every decade, scientists said, and sea level rise is now running at the extreme of projections made a few years ago.
The research, published in the journal Geophysical Research Letters, compared satellite measurements of 800 m of the ice sheet height from 1992 to 2017 with meteorological information. This distinguishes short-term changes due to variable snowfall due to long-term changes due to weather.
Satellite data map shows how glacial ice thinning has spread deep into Antarctica - video
"Since its inception in the 1990s, the thinning has progressively spread inland over the last 25 years, which is fast in glaciological terms," said Professor Andy Shepherd of the University of Leeds in the UK. Kingdom, who led the study. "The speed of extracting ice from an ice sheet used to be talked about on geological time scales, but now it has been replaced by the lives of people."
He said that the thinning of some ice currents had spread 300 miles inland along a length of 600 miles.
“More than 50% of the glacier basins on the Pine and Thwaites Islands have been affected by thinning in the last 25 years. We are halfway there and that is a concern. "
Researchers already knew that ice was being lost in West Antarctica, but the new work points to where it is happening and how quickly. This will allow for more accurate projections of sea level rises and can help prepare for these rises.
In the recent past, snow falling on Antarctic glaciers balanced the ice lost when icebergs flowed into the ocean. But now the glaciers are flowing faster than snow can replace them.
"Along a 3,000 km [1,850 mile] stretch of West Antarctica, the water in front of the glaciers is too hot," he said. This causes the bottom of the glaciers to melt, where they grind against the seabed. Melting decreases friction and allows glaciers to slide more quickly into the ocean and therefore thin.
"In parts of Antarctica, the ice sheet has thinned in extraordinary amounts," Shepherd said.
Research published in January found that ice loss across the entire Antarctic continent had increased six-fold since the 1980s, with the largest losses in the west. The new study indicates that West Antarctica has caused a 5mm rise in sea level since 1992, in line with the findings of the January study.
The expansion of the oceans as they warm and the great melt in Greenland are the main current causes of the rise in the oceans, but Antarctica is the largest ice reserve. The East Antarctic Ice Sheet contains enough ice to raise sea levels by about 60 meters. It had been considered stable, but research in December found that even this bastion was showing signs of melting.
Without rapid cuts in carbon emissions that drive global warming, melting and rising sea levels will continue for thousands of years.
"Before we had useful satellite measurements from space, most glaciologists thought that polar ice sheets were quite isolated from climate change and not changing at all," Shepherd said. "Now we know that is not true."