Newly discovered deep seabed channels beneath the Thwaites Glacier in western Antarctica could be the path for warm ocean water to melt the underside of the ice. Data from two research missions, using airplanes and ships, are helping scientists understand the contribution this huge remote glacier is likely to make to future sea level rise around the world.
Researchers from the UK and US International Thwaites Glacier Collaboration (ITGC), collected data on the Dotson and Crosson glacier and adjacent ice shelves in January-March 2019. The Otter aircraft, l Another mapped the seabed at the ice front from the US Antarctic Program’s icebreaker RV Nathaniel B Palmer.
Publication this month in the journal La cryosphère both research papers describe the discovery. The Thwaites Glacier covers 192,000 square kilometers (74,000 square miles) – the size of Britain or the US state of Florida – and is particularly sensitive to climate and ocean changes.
Over the past 30 years, the global rate of ice loss from Thwaites and its neighboring glaciers has increased more than 5-fold. Already, the ice flowing from Thwaites into the Amundsen Sea accounts for about 4% of the total. global sea level rise. An uncontrollable collapse of the glacier could cause a significant rise in sea level of about 65 cm (25 inches) and scientists want to know how fast that could happen.
Lead author Dr Tom Jordan, aero-geophysicist with the British Antarctic Survey (BAS), who led the airborne survey, said:
“It was fantastic to be able to map the canals and the cavity system hidden under the sea ice; they are deeper than expected – some are over 800 meters deep. They form the critical link between the ocean and the glacier.
“The offshore channels, along with the adjacent cavity system, are most likely the route through which warm ocean water passes under the pack ice to the stranding line, where the ice meets the bed.
Dave Porter of LDEO Columbia University, who flew over the Thwaites Glacier for the airborne survey, says:
“Flying over the recently collapsed tongue of ice and being able to see firsthand the changes taking place at Thwaites Glacier was both awe-inspiring and baffling, but also gratifying to know that the airborne data we would be collecting would allow to reveal the structures hidden below. ”
An exceptional sea ice break in early 2019 enabled RV Nathaniel B Palmer’s team to survey more than 2,000 square kilometers of seabed on the glacier’s ice front. The study area had previously been hidden under part of the floating ice shelf extending from the Thwaites Glacier, which ruptured in 2002, and for most of the following years the area was inaccessible due to the thick sea ice cover. The team’s results show that the seabed is generally deeper and has deeper channels leading to the grounding line below the pack ice than previously thought.
Lead author Dr Kelly Hogan is a marine geophysicist at BAS. She was part of the seabed monitoring team. She says:
“We have found that the coastal seabed, which is incredibly rugged, is a very good analogue of the bed under the current Thwaites Glacier, both in terms of shape and rock type. By examining the retreat patterns over this underwater terrain, we will be able to help digital modelers and glaciologists in their quest to predict future retreat.
“This research filled a critical data gap. Together, the new coastal seabed maps and cavity maps follow deep channels for more than 100 km to where the glacier rests on the bed. For the first time, we have a clear view of the tracks. along which hot water can reach the underside of the glacier, causing it to melt and contribute to the rise in sea levels around the world. “
Scientists find record warm water in Antarctica, indicating cause of disturbing glacier melt
New gravimetric bathymetry for the Thwaites, Crosson and Dotson ice shelves revealing two ice shelf populations, La cryosphère (2020). DOI: 10.5194 / tc-14-2869-2020
Revealing the ancient bed of the Thwaites Glacier using seabed bathymetry: implications for warm water tracing and bed controls on ice flow and buttress, La cryosphère (2020). doi.org/10.5194/10.5194/tc-14-2883-2020
Provided by British Antarctic Survey
Citation: Deep channels connect the ocean to the Antarctic Glacier (September 9, 2020) retrieved September 9, 2020 from https://phys.org/news/2020-09-deep-channels-link-ocean-antarctic.html
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