A gigantic two-thirds of the Manhattan area, nearly 300 meters high, was found at the bottom of Thwaites Glacier in Antarctica.
About the size of Florida, the glacier accounts for approximately 4% of the global sea level rise.
It has enough ice to raise the world's oceans a little over 65 centimeters and retreat from neighboring glaciers, raising sea levels by more than 2.4 meters if all the ice is lost, according to the Daily Mail.
The huge cave contained 14 billion tons of ice. But in the course of only three years, it melted and flowed into the Southern Ocean.
According to a NASA study, the emptiness was caused by newly discovered "fingers" of hot water flowing into cracks in the glacier caused by growing climate change. This water then accumulated between the ice and the rock, eroding the glacier above.
"As more heat and water under the glacier, it melts faster," said the study's lead author and NASA scientist, Pietro Milillo.
And the erosion of ice in the subsurface has disturbing implications.
Not only is more ice melting than previously detected, it shows that the Thwaites glacier, 160 km wide, is not as firmly fixed to the surface of the Antarctic continent as was believed.
This means that the ice mass – the size of Florida – can break and slip into the sea, much faster than projected.
Worse, the Thwaites glacier acts as a sort of "door stop", preventing contiguous glaciers from sliding toward the sea.
A recent study has warned the "apocalyptic" Antarctic glacier, which may collapse within decades.
"Understanding the details of how the ocean melts this glacier is critical to projecting its impact on rising sea levels over the next few decades," says NASA scientist Eric Rignot.
The emptiness was found by ice penetration radar and a series of satellites, all of which are trying to understand what is happening to Antarctica as the world warms up.
The potential impact is enormous.
Unlike much of the North Pole, a huge amount of ice from the South Pole lies on land.
Ice in the water does not affect sea level when it melts.
But the new water that flows into the sea does.
And Antarctica is a huge continent covered with ice.
The Thwaites glacier has enough ice above sea level to raise sea levels by more than 65 cm if it melts.
Once out, the nearby glaciers will have no obstacles in their way, accelerating their melting and potentially releasing enough water to raise sea level by up to 2.4m.
"We suspected for years that the Thwaites were not strongly attached to the bedrock below," said study author Rignot in a NASA statement. "Thanks to a new generation of satellites, we can finally see the details."
As the loss of these glaciers could result in flooding of large cities such as New York, new research teams must travel to this, one of the most difficult areas to reach on Earth.
The US National Science Foundation and the British National Environmental Research Council initiated a five-year field project, The International Thwaites Glacier Collaboration. He will begin his field observations later this year.
THE RETREAT OF GLACIER THWAITES
The Thwaites glacier is slightly smaller than the total size of the United Kingdom, approximately the same size as Washington State, and is located in the Amundsen Sea.
It is up to 4000 meters and is considered a key to making projections of global sea level rise.
The glacier is retreating from the ocean's warming and is believed to be unstable because its interior is more than two kilometers below sea level, while, on the coast, the bottom of the glacier is quite shallow.
The Thwaites glacier has experienced a significant flow acceleration since the 1970s.
From 1992 to 2011, the center of the Thwaites ground line receded at almost 14 kilometers.
The annual ice discharge of the region as a whole has increased 77 percent since 1973.
As its interior connects to the vast portion of the ice sheet of West Antarctica, which lies deep below sea level, the glacier is considered a gateway to most of the potential contribution of sea level in West Antarctica.
The collapse of the Thwaites Glacier would cause a global sea level rise of between one and two meters, with potential for more than double the entire West Antarctic ice sheet.