World’s Deepest Land Canyon Discovered in Antarctica

Rodiano Bonacci
Dicembre 14, 2019

The research which is part of the newly released Antarctica topography map -BedMachine zeros the lowest point on land beneath the Denman Glacier in East Antarctica.

Among the most striking discoveries, the researchers say, are stabilising ridges that protect the ice flowing across the Transantarctic Mountains and a bed geometry that increases the risk of rapid ice melting in the Thwaites and Pine Island glaciers sector of West Antarctica.

The new map will help scientists identify regions of ice that are likely to be more or less susceptible to the deleterious effects of climate change.

The "BedMachine Antarctica" study will be presented at the American Geophysical Union and is also available in the Nature Geoscience journal. "If its grounding line - where the ice starts to float - starts to retreat in this deep canyon, it could retreat rapidly due to a mechanism called Marine Ice Sheet Instability." he said.

The new Antarctic bed topography product was constructed utilizing ice thickness information from 19 totally different research institutes dating back to 1967, encompassing nearly a million line-miles of radar soundings. The mapping model utilized ice flow velocity and seismic data, as well as topography measurements made by NASA's Operation IceBridge surveys.

Previous Antarctica mapping methods relying on radar soundings have been generally effective, but with some limitations, the researchers say. An aircraft's wing-mounted radar systems emit a signal that penetrates glaciers and ice sheets and bounces back from the point at which the ice meets solid ground.

Dr Morlighem's solution has been to use some physics - mass conservation - to plug these holes. This technique was instrumental in the research team's conclusion regarding the true depth of the Denman trough.

Lead author Mathieu Morlighem, of University of California, Irvine, said: 'There were lots of surprises, especially in regions not previously mapped in great detail. The Denman canyon is 3.500 meters below sea level, being the lowest point on land not covered by liquid water. For instance, if it's known how much ice is entering a narrow valley and how fast it's moving - the volume of that ice can be worked out, giving an insight into the depth and roughness of the hidden valley floor.

"The biggest challenge was that Antarctica is huge... so applying this method to the entire coast was very time-consuming: it took about five years to get to BedMachine", he said.

To build the new map, scientists sourced data from a wide diversity of sources, including observations from 19 surveys of Antarctic ice thickness.

The discovery was announced by the University of California, Irvine (UCI) on Thursday.

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