Antarctica’s Doomsday Glacier could ‘snowball’ towards collapse, as a study shows the ice is melting faster than expected.
Scientists from the University of Edinburgh predict that the glacier – whose official name is Thwaites – could shed 200 gigatonnes of ice every single year by 2067.
That is more than the current ice loss of the entire Antarctic Ice Sheet, which has been losing 150 gigatonnes of ice per year for the last two decades.
Worryingly, the ice loss would add an extra 0.5mm of sea level rise per year, outpacing the contribution of all the world’s mountain glaciers.
The Doomsday Glacier is a slow–moving river of ice about the size of the UK that contains enough fresh water to raise sea levels by a whopping 65 centimetres.
While the researchers don’t believe that total collapse is imminent, lead author Dr Daniel Goldberg says that the glacier is now accelerating towards disaster.
He told the Daily Mail: ‘That rate of 200 megatonnes per year could then increase quite quickly, and that instability could lead to collapse.
‘That would be catastrophic for hundreds of millions, if not billions, of people in coastal cities around the world.’
Scientists say that West Antarctica’s Thwaites Glacier could lose 200 megatonnes of ice every year by 2067, as a study shows the glacier is melting faster than expected. Pictured: Maps showing models of ice loss speed on the Thwaites Glacier
The Thwaites Glacier is one of the most important bodies of ice in the entire Antarctic Ice Sheet.
It acts like a river, draining ice and snow from a huge area of the West Antarctic Ice Sheet out into the Amundsen Sea.
This makes it critical for maintaining the stability of the entire Antarctic Ice Sheet, with any potential collapse having widespread consequences.
However, the Doomsday Glacier is also one of the continent’s fastest–changing glaciers, with satellite data showing that it is both thinning and accelerating in its flow towards the sea.
Studies have found that the Thwaites Glacier is now losing ice five times faster than in the 1990s.
In their study, published in the journal Geophysical Research Letters, the researchers calculated how the glacier will melt using a ‘satellite calibrated ice sheet model’.
This involved a computer simulation that modelled the physics of ice flow, ocean melting, and surface conditions, and calibrated it to match real–world observations.
Most studies do this using satellite observations of ‘velocity’ – how fast the ice is moving towards the ocean.
However, in their study, the researchers also looked at satellite measurements of elevation.
Their elevation–based models not only matched the real–world data more closely, but also predicted much more rapid ice loss.
This suggests that Thwaites may lose ice in the future far more quickly than other scientists have suggested.
But the key detail revealed by these simulations was how and where this rapid melting began.
The simulations showed that the most rapid ice loss occurred over deep troughs in the Antarctic bedrock stretching up to 60 miles (100 km) inland.
While human–caused climate change is warming the Amundsen Sea and causing more melting, this suggests that Thwaites’ recent acceleration might have more to do with underlying geology.
‘Where Thwaites is now going at its absolute fastest, it is sitting on top of this valley that goes directly inland,’ explains Dr Goldman.
‘What I saw in the simulations is that the glacier is retreating into that valley, and the more it retreated into the valley, the faster it accelerated.’
The acceleration was concentrated over a deep valley running inland (circled). Scientists say that this geological feature is a major reason for Thwaites rapid melting
At the current rate of emissions, Dr Goldman thinks that the Doomsday Glacier will undergo catastrophic collapse in around 200 years.
However, Thwaites responds extremely slowly to climate change, with the glacier currently reacting to changes that happened from the 1980s through to the late 20th century.
That means the glacier will also be a lot less responsive to our efforts to slow its retreat.
If humans cut emissions, Dr Goldman says the collapse could be delayed by centuries, but we might not see the impact of green policies for generations.
He explained: ‘It would be a bit disingenuous to say, “stop burning fossil fuels today and stop losing ice tomorrow”.
‘It could take a century for any changes we make today to be evident in the loss of mass from Thwaites.
‘It’s a scary thought because humanity, if they care about sea level rises, will have to change their behaviour and not really see the outcomes while any of us are still alive.’
THE RETREAT OF THE THWAITES GLACIER
The Thwaites glacier is slightly smaller than the total size of the UK, approximately the same size as the state of Washington, and is located in the Amundsen Sea.
It is up to 4,000 metres (13,100 feet thick) and is considered a key in making projections of global sea level rise.
The glacier is retreating in the face of the warming ocean and is thought to be unstable because its interior lies more than two kilometres (1.2 miles) below sea level while, at the coast, the bottom of the glacier is quite shallow.
The Thwaites glacier is the size of Florida and is located in the Amundsen Sea. It is up to 4,000 meters thick and is considered a key in making projections of global sea level rise
The Thwaites glacier has experienced significant flow acceleration since the 1970s.
From 1992 to 2011, the centre of the Thwaites grounding line retreated by nearly 14 kilometres (nine miles).
Annual ice discharge from this region as a whole has increased 77 percent since 1973.
Because its interior connects to the vast portion of the West Antarctic Ice Sheet that lies deeply below sea level, the glacier is considered a gateway to the majority of West Antarctica’s potential sea level contribution.
The collapse of the Thwaites Glacier would cause an increase of global sea level of between one and two metres (three and six feet), with the potential for more than twice that from the entire West Antarctic Ice Sheet.
