The melting of the poles is accelerating at a dizzying speed. Giant Thwaites Glacier, a gigantic ice stream the size of England and contained in Antarctica Occidental is already in a rapid retreat, according to new images of the seafloor in the highest resolution ever. Total loss of glacier and surrounding ice basins can raise sea level 1 to 3 metersAs published by researchers in the journal ‘Nature Geoscience’.
This rapid retreat has created widespread concern about exactly how much, or how quickly, its ice may give to the ocean.
The new study, led by marine geophysicist Alastair Graham of the University of South Florida’s School of Marine Sciences, add cause for concern. For the first time, scientists have mapped a critical area of ​​the seafloor in front of the glacier in high resolution, allowing them to understand how quickly Thwaites retreated and moved in the past.
The stunning images show geological features that are new to science and also provide a kind of crystal ball for Thwaites to see into his future. In both humans and ice sheets, past behavior is key to understanding future behavior.
The team documented more than 160 parallel ridges that were created like a trail as the glacier’s leading edge receded and rose. and went down with the daily tides. “It’s like you’re looking at a tide gauge at the bottom of the sea,” Graham explains, “I was really amazed by the beauty of the data.”
Beauty aside, what’s alarming is that the Thwaites retracement rate that scientists have documented recently is small compared to faster rates of change in the past, Graham said.
To understand Thwaites’ past seclusion, the team analyzed submerged rib-like formations 700 meters below the polar ocean and took into account the region’s tidal cycles, as computer models predicted, to show that a “rib” should form each day.
In the last 200 years, in less than six months, the glacial front lost contact with a seafloor ridge and retreated at more than 2.1 kilometers per yearBetween 2011 and 2019, it doubled the rate documented using satellites.
“Our results show that very rapid retreating pulses have occurred on the Thwaites Glacier in the last two centuries, and possibly in the mid-20th century,” says Graham.
“We expect to see big changes from year to year”
” it’s barely catching up today and we expect to see big changes on small time scales in the future—even year after year—when it moves beyond a shallow ridge in the glacier bed,” adds Robert Larter, a marine geophysicist and co-author of the British Antarctic Survey.
To collect the images and supplement the geophysical data, the team, which includes scientists from the US, UK and Sweden, launched a cutting-edge orange robotic vehicle equipped with imaging sensors called ‘Rán’ from R/V Nathaniel B. Palmer during an expedition in 2019.
Run by scientists from the University of Gothenburg, Sweden, Rán embarked on a 20-hour mission that was “as risky as it was random,” according to Graham. The team mapped an area of ​​the seafloor the size of Houston in front of the glacier.and it did so under extreme conditions during an unusual summer with no sea ice. This allowed them to access the front of the glacier for the first time in history.
“This is a pioneering study of the ocean floor made possible by the latest technological advances in autonomous ocean mapping and the Wallenberg Foundation’s bold decision to invest in this research infrastructure,” said Anna Wahlin, a physical oceanographer at the University of Gothenburg. The images Rán collected give us a vital insight into the processes occurring today at the critical juncture between the glacier and the ocean.”
“This was really a once-in-a-lifetime task,” says Graham, who said the team wanted to directly sample the seafloor sediments so they could more accurately date the ridge features. we had to.
While many questions remain, one thing is certain and that is Scientists used to think that Antarctic ice sheets were lazy and slow to react, but that’s not true.He points to Graham.
According to the United Nations, about 40% of the human population lives 100 kilometers from the coast.
“This work is part of a collective, interdisciplinary effort to better understand the Thwaites Glacier system,” said Tom Frazer, dean of the USF School of Marine Sciences. It’s an important step in providing information.”
Reference work: https://www.nature.com/articles/s41561-022-01019-9
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Environment department contact address:crisclimatica@prensaiberica.es
Source: Informacion
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