Scientists warn critical Antarctic ice shelf could break in next five years

Satellite images taken no later than last month, which researchers presented at the American Geophysical Union’s annual meeting on Monday, suggest that the critical ice shelf that holds the Thwaites Glacier in western Antarctica – an important defense against sea-level rise – could break down over the next three to five years.

Antarctica’s Thwaites Glacier is known as the “Last Judgment Glacier” because of the serious risk it poses during its melting process. It dumped billions of tons of ice in the sea and its disappearance could lead to irreversible changes all over the planet.

The glacier, which is the size of Florida or Britain, already accounts for about 4% of annual global sea level rise, loses about 50 billion tonnes of ice each year, and becomes highly vulnerable to the climate crisis. Falling pack ice could lead to the imminent collapse of the Antarctic Critical Glacier.

If the Thwaites collapsed, the event could raise sea level by several meters, the researchers said, further endangering coastal communities as well as low-lying island nations.

But Ted Scambos, a glaciologist at the University of Colorado at Boulder and leader of the International Thwaites Glacier Collaboration, said it will be decades before the world experiences a real acceleration and further rise in sea level. .

“What draws attention to Thwaites is that change will happen with some pretty dramatic and measurable results over the next few decades,” Scambos told CNN.

For now, the glacier is held back by a critical floating ice shelf.

“What is most concerning about the recent results is that they point to a collapse of this ice shelf, this kind of safety strip that keeps the ice on the ground,” Peter Davis told CNN. , oceanographer at the British Antarctic Survey. “If we lose this pack ice, the glacier will flow into the ocean more quickly, contributing to sea level rise.”

Warming ocean waters are playing a key role in the rapid deterioration. A 2020 study by the International Thwaites Glacier Collaboration, which is currently leading ongoing research in Antarctica, found that the ocean floor is deeper than scientists previously thought, with deep passages allowing for warm ocean water melts the underside of the ice.

Observations show that the critical ice shelf that holds the Thwaites together loosens its grip on the Seamount, or Seamount, which acts as a back-up against the river of ice that does not flow into it. warm ocean. The researchers also found that the so-called “ice tongue” of the Thwaites Glacier is now simply a “loose cluster of icebergs,” which no longer influences the stable part of the eastern ice shelf.

Hot water also threatens the “stranding zone”, where ice meets the seabed. Davis and his team used hot water to poke access holes from the sea ice surface and deep into the ocean cavity below. In doing so, they discovered that not only are the ocean waters in the earth line warm, by polar standards, but also salty, preparing the landscape for further erosion.

Peter Washam, an associate researcher at Cornell University, who is also participating in the research, said the physical features of the stranding area show signs of chaos, such as hot water, rugged ice and a Steep, sloping bottom that allows water to quickly melt the ice sheet from below.

Sea ice floats from NASA's Operation IceBridge research aircraft in the Antarctic Peninsula region November 4, 2017, over Antarctica.

“In the years to come, we expect the Thwaites ground line in the region to slowly retreat up the seabed slope it currently sits on as the warm ocean eats away at its edge. underside, ”Washam told CNN. His team used an underwater vehicle called Icefin that makes it easier to study ice and water around and under pack ice.

The bottom line, Davis says, is that Antarctica’s Thwaites Glacier is deteriorating rapidly. Warm ocean water slowly clears the ice below, causing the water to flow faster, further fracturing the ice and bringing the looming threat of collapse even closer.

“From satellite data, we see these large fractures spreading across the ice floe surface, essentially weakening the ice tissue; much like a crack in a windshield,” he said. “It spreads slowly over sea ice and will eventually fracture into many different pieces.”

Iceberg 80 times the size of Manhattan could destroy fragile South Atlantic ecosystem

Scambos said that although the process is extremely slow and the real impacts will not be felt until decades later, it is almost impossible to stop it.

“This is a geological process, but it occurs almost on the scale of a human lifetime,” he said. “As a disaster for people alive today, it is moving extremely slowly. The best way is to try and slow down the forces that are pushing the ice in that direction.”

And as the ramifications of the climate crisis spread around the world, researchers say expanding scientific research to understand changes in the Arctic and Antarctic regions is critical to planning for mitigation strategies such as coastal defenses in vulnerable communities.

“There’s really nothing we can do to stop this from happening,” besides slowing it down, Davis said. “The way we’ve managed our carbon emissions so far has caused these changes – and essentially, we’re taking the consequences of what we’ve emitted over the past two decades, if not more.”


Source link

Comments are closed.