Doomsday Glacier ‘Gripping By Its Claws’ – Spine-Chilling Retreat Could Raise Sea Levels 10 Feet

Doomsday Glacier 'Gripping By Its Claws' - Spine-Chilling Retreat Could Raise Sea Levels 10 Feet
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Thwaites Glacier Nathaniel B Palmer

R/V Nathaniel B. Palmer captured by drone on the Thwaites Glacier ice front in February 2019. Credit: Alexandra Mazur/University of Gothenburg

Faster into the past: New seafloor images – the highest resolution ever taken from the West Antarctic Ice Sheet – better understand the retreat of the Thwaites Glacier.

At times in the past, the massive Thwaites Glacier retreated faster than it does today, raising concerns about its future.

The Thwaites Glacier, also known as the Doomsday Glacier in West Antarctica, has been an elephant in the room for scientists trying to make predictions about global sea level rise.

This massive ice sheet is already in rapid retreat (“recession” when looking at geologic time tables). This has led to widespread concerns about exactly how much, or how fast, it can release ice to the ocean.

Thwaites Ice Shelf Multibeam Bathymetry

A 3D-rendered view of depth-colored polyhedral bathymetry (the shape of the sea floor) collected by Ran across the seafloor ridge in front of the Thwaites Ice Shelf. Credit: Alastair Graham / University of South Florida

The potential impact of Thwaites’ retreat is spine-chilling: the total loss of the glacier and surrounding ice basins could raise sea levels by 3 to 10 feet. The glacier is roughly the size of Florida.

“Thwaites is really holding on today, and we should expect to see big changes on small time scales in the future as the glacier retreats to a shallow ridge on its bed.” — Robert Larter

a new study published

“It’s like looking at a tide gauge at the bottom of the sea,” Graham said. “It really blows my mind how beautiful the data is.”

Beauty aside, what’s troubling is that the rate of Thwaites retreat that scientists have recently documented is small compared to the fastest rate of change in the past, Graham said.

To understand Thwaites’ past retreat, scientists analyzed rib-like formations submerged 700 meters (about 2,300 feet, or half a mile) below the Arctic Ocean, which affected the tidal cycle for the region as predicted by computer models. show that a rib is formed every day.

Rán Kongsberg HUGIN Autonomous Underwater Vehicle

Rán, the Kongsberg HUGIN autonomous underwater vehicle, among the sea ice in front of the Thwaites Glacier after a 20-hour mission mapping the seabed. Credit: Anna Wåhlin/University of Gothenburg

At some point in the last 200 years, in less than six months, the glacier front lost contact with the seafloor ridge and retreated at a rate of more than 2.1 kilometers per year (1.3 miles per year). This is more than double the rate documented using satellites between 2011 and 2019.

“Our results show that there have been pulses of very rapid retreat on Thwaites Glacier over the past two centuries and possibly into the mid-20th century,” Graham said.

“Thwaites is really holding its claws today, and once the glacier retreats to a shallow ridge on its bed, we should expect to see big changes on small time scales in the future,” said Robert Larter, a marine geophysicist and co-author of the British Antarctic Survey.

Thwaites Glacier Landsat 8 satellite map

Landsat 8 satellite imagery collected in February 2019 shows a map of the Thwaites Glacier. The autonomous underwater vehicle’s mission track is shown in orange. Changes in the grounding line positions of Thwaites Glacier in the recent past are shown by colored lines. Credit: Alastair Graham / University of South Florida

To collect the images and supporting geophysical data, the research team, which included scientists from the US, UK and Sweden, launched a state-of-the-art orange robotic vehicle loaded with imaging sensors called Rán. R/V Nathaniel B. Palmer during an expedition in 2019.

Piloted by scientists at the University of Gothenburg in Sweden, Rán embarked on a 20-hour mission that was as risky as it was random, Graham said. He mapped an area of ​​seafloor the size of Houston in front of the glacier, and did so under extreme conditions during an unusual summer marked by a lack of sea ice.

This allowed researchers to enter the glacier front for the first time in history.

“This was a pioneering study of the ocean floor, made possible by recent technological advances in autonomous ocean mapping and the Wallenberg foundation’s bold decision to invest in this research infrastructure,” says Anna Vahlin, a physical oceanographer at the University of Gothenburg. Posted in Ran Thwaites. “The images collected by RAN give us vital insights into the processes taking place today at the critical junction between the glacier and the ocean.”

“This was really a once-in-a-lifetime mission,” Graham said, adding that the team wanted to directly sample seafloor sediments so they could more accurately identify ridge-like features.

“But the ice quickly shut us down and we had to leave before we could do that on this expedition,” he said.

Alastair Graham and Robert Larter

THOR scientists Alastair Graham (right) and Robert Larter (left) admire the crumbling ice face of the edge of the Thwaites Glacier from the bridge deck of the R/V Nathaniel B. Palmer. Credit: Frank Nitsche

Although many questions remain, one thing is certain: in the past, scientists answered the Antarctic ice sheets slowly and slowly, but according to Graham, this is simply not true.

“A small jab at Thwaites can cause a big reaction,” he said.

According to the United Nations, about 40 percent of the human population lives within 60 miles of a coast.

“This research is part of a collective, cross-disciplinary effort to better understand the Thwaites Glacier system,” said Tom Frazer, dean of the USF College of Marine Sciences. from the mind. This study is an important step forward in providing important data to inform global planning efforts.”

Reference: “Rapid retreat of Thwaites Glacier in pre-satellite times” by Alastair GC Graham, Anna Wåhlin, Kelly A. Hogan, Frank O. Nitsche, Karen J. Heywood, Rebecca L. Totten, James A. Smith, Claus- Dieter Hillenbrand, By Lauren M. Simkins, John B. Anderson, Julia S. Wellner, and Robert D. Larter, 5 September 2022, Natural Geology.
DOI: 10.1038/s41561-022-01019-9

The research was supported by the National Science Foundation and the UK Natural Environment Research Council through the International Thwaites Glacier Collaboration.

The 2019 expedition was the first of a five-year project called THOR, which stands for Thwaites Offshore Research, and also included team members from a sister project called Thwaites-Amundsen Regional Research and the Integrating Atmosphere-Ice-Ocean Processes Network, or TARSAN. .

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