West Antarctica’s Thwaites Glacier, nicknamed the “Ending Glacier”/NASA/OIB/Jeremy Harbeck
2023.02.18 Sat posted at 18:30 JST
（ＣＮＮ） Antarctica’s Thwaites Glacier, dubbed the ‘end of the world’ glacier because its collapse would lead to catastrophic sea-level rise, is melting rapidly and unexpectedly, a new study reveals.
Thwaites Glacier is about the size of Florida and is located in western Antarctica. One of the topography that supports this is the ice shelf overhanging the sea surface. Ice shelves act like corkscrews, keeping glaciers on land and providing important defenses against rising sea levels.
But as the ocean warms, this vital ice shelf is becoming increasingly vulnerable.
The lower part of most ice shelves melted at a slower rate than previously thought, but deep cracks and “stepped” sections showed the same rate, according to two papers published Wednesday in the scientific journal Nature. Melting proceeded at a much faster speed.
Thwaites Glacier is changing rapidly as climate change accelerates.
Thwaites Glacier releases billions of tons of ice into the ocean each year, accounting for about 4% of annual sea level rise. In particular, the rate of melting is rapid where the glacier meets the seafloor. The point of contact between the glacier and the seafloor has receded nearly 14 kilometers since the late 1990s, further expanding the area of ice exposed to relatively warm seawater.
A complete collapse of Thwaites Glacier alone could lead to more than 70 centimeters of sea level rise. While this is large enough to wipe out coastal areas around the world, Thwaites Glacier also acts as a natural dam against the surrounding ice, and if it collapses, it could ultimately raise global sea levels by about 3 metres. Scientists estimate that it could reach
Cracks on the surface of Thwaites Glacier (photographed in 2020)
In late 2019, a US-UK research team participating in the International Thwaites Glacier Collaborative traveled to Antarctica to better understand changes in the inaccessible Antarctic coast.
The research team used a hot water drill to drill a hole nearly 600 meters deep into the ice. Over the course of five days, various instruments were lowered into the holes to obtain glacier measurement data.
One such instrument, a torpedo-like robot called “Ice Fin,” has gained access to areas that were previously largely unexplorable. A remote-controlled ice fin was responsible for capturing images and recording information about water temperature, salinity and ocean currents.
Exploratory drilling station on Thwaites Glacier/Peter Davis/British Antarctic Survey/ITGC
Britney Schmidt, a Cornell University associate professor and lead author on one of the papers, said Icefin was able to “swim to very dynamic locations and get data on everything from the ocean floor to the glacier.” .
Peter Davies, an oceanographer with the British Antarctic Survey and lead author on the other paper, told CNN that the findings reveal “a very nuanced and complex picture”. Indicated.
Torpedo-shaped robot “Ice Fin” that collects data under sea ice
The study found that while Antarctica is retreating, it is melting slower than expected under the flat parts of the ice shelf. The melting rate averaged between 2 and 5.4 meters per year, less than predicted by previous models.
But the glacier’s submerged topography was much more complex than expected, with stepped terracing and fissures everywhere, and large fissures cutting through the ice shelves.
It turns out that the melting speed is particularly fast in these parts. Warm, salty water was seeping through cracks and fissures, widening them and further destabilizing the glacier.
The tip of an “ice fin” loaded with various devices/Britney Schmidt/Justin D. Lawrence/ITGC
“The glacier is melting not only from below, but also from within,” Schmidt said.
Melting of cracks and terraced slopes “could be the main triggers for ice shelf collapse,” the authors said.