Antarctica's 'Doomsday Glacier' is even more dangerous than we thought: Study says sea levels could rise TWICE as much as previous estimates

Antarctica's 'Doomsday Glacier' is even more dangerous than scientists had previously thought, a new study has found.

The Thwaites Glacier in western Antarctica is a huge river of ice covering an area larger than Great Britain.

If it were to collapse completely, it has the potential to raise sea levels by a staggering 26 inches (65 centimetres) and wreak havoc on the world's coastal regions. 

While researchers don't believe a total collapse is imminent, they warned the glacier is now accelerating towards disaster. 

New predictions reveal warming ocean waters are eroding its base faster than expected, and could add up to 1.2 inches (30mm) of sea level rise by 2100 - doubling previous estimates.  

This massive adjustment is because their new model uses a more accurate understanding of what is happening beneath the base of the glacier.

Co-author Professor Eric Rignot, from the University of California, said: 'Most projections to date have struggled to match the rapidity of the mass loss because of missing physics; our new model with more complete physics can match the record and then produces projections that are twice as large as before.

'These results predict greater risk of and exposure to coastal flooding than anticipated in the coming decades.'

Over the last few decades, the Thwaites Glacier has shown an alarmingly fast rate of thinning and retreat.

However, the computer models used by scientists to make predictions about the glacier's future have been coming out of alignment with the data revealed by satellites.

The models predict that the glacier should be moving into the ocean at a much slower rate than the rapid acceleration scientists are now observing.

In their new paper, published in the journal Nature Communications, Professor Rignot and his co-authors attempted to make a model that was a better fit to reality.

Lead author Dr Mattia Poinelli, of UC Irvine, says: 'Glaciologists have long based their assumptions of ice sheet dynamics on the "grounding line", a discrete, narrow and mostly stable demarcation where ice leaves the land and begins floating on water.'

'We have come to acknowledge a different arrangement beneath Earth's major ocean-terminating glaciers.'

Satellite observations now show that glaciers really end in what scientists call a 'grounding zone'.

This is a large area, sometimes miles across, where warm water seeps deep underneath the ice sheet and triggers rapid melting.

The researchers looked at data collected by the Finnish ICEYE satellite constellation, which measures small movements in the ice surface.

This data showed that seawater actually penetrates several miles beneath the grounded ice, lifting it up during tidal cycles.

As the ice lifts, the grounding zone is flushed with pressurised, warm seawater that is being pushed into the Antarctic coastline by currents already altered by climate change.

Using these new observations to model Thwaites' future behaviour, the researchers discovered that the glacier is likely to melt much faster than previously thought.

They were then able to reconstruct historical glacier change from the 1990s to the present that is four times more pronounced than traditional models.

A major concern is the fact that these grounding zone processes appear to be accelerating the detachment of the Thwaites Glacier from its stabilising ridges.

Currently, the Doomsday Glacier's flow into the ocean is being held back by critical points where the ice is attached to elevated parts of the seabed, such as the vital Mouginot Ridge.

However, as water is forced up and under the ice, melting processes are wearing away that grounding connection.

According to their new model, there is now a 60 per cent chance that Thwaites will become disconnected from the Mouginot Ridge by the end of the century.

Dr Poinelli says: 'Once that ridge is unpinned, the glacier will continually retreat across a predominantly retrograde seafloor toward its next topographic high, the South Ridge.'

This comes after studies suggested that the Thwaites Glacier is close to losing its entire ice shelf in the coming year or so.

The Thwaites Eastern Ice Shelf is a wall of ice attached to the glacier's eastern flank, holding back the flow of ice into the sea.

This supporting barrier is over 1,150ft (350m) thick and covers 580 square miles (1,500 square kilometres) – about the area of Greater London.

However, the Antarctic's warming oceans are now thinning this frozen bulwark at an alarming rate.

Speaking in May, Dr Robert Larter, a marine geophysicist at the British Antarctic Survey, warned that the shelf's breakup is 'very likely to happen sometime this year'.