NASA's new study shows that Antarctica's glaciers aren't just melting around the edges. Warm water is melting them from beneath, speeding up the rate of sea level rise. Photo / via NASA
NASA's new study shows that Antarctica's glaciers aren't just melting around the edges. Warm water is melting them from beneath, speeding up the rate of sea level rise. Photo / via NASA
A gigantic cavity two-thirds the area of Manhattan and almost 300 metres tall has been found at the bottom of Thwaites Glacier in Antarctica.
About the size of Florida, the glacier is responsible for approximately 4 per cent of global sea level rise.
It holds enough ice to raise the world oceans a little over 65cm and backstops neighbouring glaciers that would raise sea levels an additional 2.4 metres if all the ice were lost, according to the Daily Mail.
About the size of Florida, Thwaites Glacier is currently responsible for approximately 4 per cent of global sea level rise. Photo / via NASA
The enormous cavern once held 14 billion tonnes of ice. But, in the course of just three years, it has melted and flowed into the Southern Ocean.
According to a study by NASA, the void was caused by newly discovered "fingers" of warm water flowing into cracks in the glacier caused by mounting climate change. This water then pooled between the ice and rock, eroding away the glacier above.
"As more heat and water get under the glacier, it melts faster," study lead author and NASA scientist Pietro Milillo said.
And the subsurface ice erosion has disturbing implications.
Not only is more ice melting than previously detected, it shows the 160km wide Thwaites Glacier is not as firmly fixed to the surface of the Antarctic continent as believed.
This means the mass of ice — about the size of Florida — can break up and slip into the sea, much faster than projected.
Worse, Thwaites Glacier acts as a kind of "door stop", preventing adjoining glaciers from sliding towards the sea.
One recent study warned the "doomsday" Antarctic glacier that could collapse within decades.
"Understanding the details of how the ocean melts away this glacier is essential to project its impact on sea level rise in the coming decades," says NASA scientist Eric Rignot.
The void was found by ice-penetrating radar and a series of satellites, all of which are attempting to understand what's happening to Antarctica as the world warms.
The potential impact is enormous.
Unlike much of the North Pole, an enormous amount of South Pole ice sits on land.
Ice that sits on water does not affect sea levels when it melts.
But new water that flows into the sea does.
A disaster scenario of West Antarctic ice sheet disintegration could occur much sooner than previously thought. Photo / via NASA
A view from a NASA airplane of large icebergs that have broken from the calving side of Thwaites Glacier in Antarctica in November 2014. Photo / via NASA
And Antarctica is an enormous, ice-covered continent.
Thwaites Glacier alone holds enough ice above sea level to raise sea levels by more than 65cm if it was to melt.
Once gone, surrounding glaciers will have no obstacle in their path, speeding up their melting and the potential release of enough water to raise sea levels by as much as 2.4m.
"We have suspected for years that Thwaites was not tightly attached to the bedrock beneath it," study author Rignot said in a NASA statement. "Thanks to a new generation of satellites, we can finally see the detail."
As the loss of these glaciers could result in the inundation of major cities, such as New York, new research teams are set to travel to this, one of the hardest to reach areas on Earth.
The US National Science Foundation and British National Environmental Research Council have initiated a five-year field project, The International Thwaites Glacier Collaboration. It will begin its field observations later this year.
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 4000 metres 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 below sea level while, at the coast, the bottom of the glacier is quite shallow.
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.
Annual ice discharge from this region as a whole has increased 77 per cent 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, with the potential for more than twice that from the entire West Antarctic Ice Sheet.
