Fast-consuming Antarctic glaciers in the past are disappearing faster, raising concerns about the future
Thwaites Glacier in West Antarctica, about the size of Florida, is the elephant in the room for scientists trying to make global sea-level predictions. On geological timescales, the giant ice stream is rapidly retreating—in effect, collapsing. This has led to widespread concerns about how quickly it might release the ice into the ocean. The potential impact is eerie: The complete loss of Thwaites and the surrounding icy basin could raise sea levels from 3 feet to 10 feet.Now, a new research natural geosciences Added reason for concern.
In this study, for the first time, scientists have mapped key areas of the seafloor in front of the glacier in high resolution. The team recorded more than 160 parallel ridges, which resemble footprints, as the glacier’s front retreated and fluctuated up and down with daily tides at some point over the past 200 years. Shockingly, the ridges demonstrated a much faster retreat than scientists have recently recorded.
To understand Thwaites’ past retreat, the team analyzed ribbed formations submerged 700 meters (less than half a mile) below the polar ocean, taking into account tidal cycles in the region, as predicted by computer models. This shows that a rib must be formed every day. At some point in less than six months, the glacier front lost contact with the seabed ridge and was retreating at a rate of more than 2.1 kilometers (1.3 miles) per year—twice the rate recorded using satellites between 2011 and 2019. times.
U.S. research vessel Nathaniel B. Palmer photographed by drone on the Thwaites Ice Front in February 2019. (Alexandra Mazur/University of Gothenburg)
“It’s as if you’re looking at a tide gauge on the ocean floor,” said lead author Alastair Graham of the University of South Florida. “Our results suggest that very things have happened to Thwaites Glacier over the past two centuries. Rapid retreat pulse, most recent probably in the mid-20th century.th century,” he said.
Robert Larter, study co-author from the British Antarctic Survey, said: “Thwaites really sticks around today on its nails, and we should expect to see big changes on small timescales in the future.”
The research team includes Frank Niche Columbia Climate School’s Lamont-Doherty Earth Observatoryand other scientists from the US, UK and Sweden.
To collect imagery and support geophysical data, scientists launched a sensor-equipped robot from a U.S. icebreaker Nathaniel B. Palmer During the 2019 expedition. The robot embarks on a 20-hour mission that is both adventurous and unexpected. It maps an area of ​​the seabed in front of a glacier in summer, an area about the size of Houston known for its lack of sea ice, allowing scientists to access the glacier front for the first time ever.The expedition itself is described by scientists in the companion file.
3D rendered view of the shape of the ocean floor, shaded by depth, collected in front of the Thwaites Ice Shelf. (Alastair Graham/University of South Florida)
Graham said the team wanted to sample seafloor sediment directly so they could more accurately identify ridge-like features. “The ice was approaching us very quickly and we had to get out before we could do that,” he said.
Scientists used to think the Antarctic ice sheet was slow to respond to climatic conditions, but that’s no longer the case, Graham said. “A little kick on Thwaites could have a big repercussion,” he said.
The study is a long-term international cooperation Research Thwaites and inform global efforts to plan for sea level rise. About 40 percent of the population lives within 60 miles of the coast, according to the United Nations.
The research was supported by the US National Science Foundation and the UK’s Natural Environment Research Council.
Adapted from a press release from the University of South Florida.
