A new map reveals detailed features of Antarctica’s hidden land

Antarctica’s ice sheet is the largest mass of ice on Earth, and about half the ice sheet is more than 5 kilometers (3 miles) from any bed topography measurement.

This means that what lies beneath is still largely a mystery and many data gaps in the topography of the land beneath the ice still exist in many parts of this frigid continent. Even though the top side of Antarctica may look relatively featureless, the land beneath the ice is textured just like any other landmass on Earth.

It is the texturing, in other words, the mountains, valleys, and ridges making up the bed topography of this ancient continent, which is so important in predicting how and when the ice will flow and which regions of ice are most vulnerable in a warming world.

“Ultimately, BedMachine Antarctica presents a mixed picture: Ice streams in some areas are relatively well-protected by their underlying ground features, while others on retrograde beds are shown to be more at risk from potential marine ice sheet instability,” says Mathieu Morlighem, UCI associate professor of Earth system science and lead author of the paper describing the newly released Antarctica bed topography map.

Mathieu Morlighem / UCI

A closer look at NASA’s BedMachine Antarctica map
The new BedMachine Antarctica map makes use of multiple technologies, including ice movement measurements, seismic measurements, radar, firn correction parameters, satellite imagery and a number of other parameters to create the most detailed picture yet of Antarctica’s hidden features.

“Using BedMachine to zoom into particular sectors of Antarctica, you find essential details, such as bumps and hollows beneath the ice that may accelerate, slow down or even stop the retreat of glaciers,” Mathieu Morlighem, an Earth system scientist at the University of California, Irvine and the lead author of the new paper published in Nature Geoscience, said.

The new Antarctic bed topography product was constructed using ice thickness data from 19 different research institutes dating back to 1967. This database was massive and included nearly one-million line miles of radar soundings. Ice shelf bathymetry measurements from NASA’s Operation IceBridge campaigns, as well as ice flow velocity, were also used, reports Phys.org.

Rift in Pine Island Glacier ice shelf, West Antarctica, photographed from the air during a NASA Operation IceBridge survey flight on November 4, 2016. This rift is the second to form in the center of the ice shelf in the past three years. The first resulted in an iceberg that broke off in 2015.

Nathan Kurth/NASA

BedMachine also makes use of a physics-based method of mass conservation to figure out what lies between the radar sounding lines, combining this with ice-flow motion to see how ice flows around the various bumps and hollows on the bed topography.

Using this method also led to scientists being able to determine the depth of the Denman trough. It is the deepest narrow canyon on Earth and lies beneath the Denman Glacier. Stretching more than 3,500 meters (11,500 feet) below sea level, the land beneath this ice stream is nearly as deep as the average depth of the ocean, and eight times deeper than the shores of the Dead Sea, which is the lowest exposed land on Earth.

“There have been many attempts to sound the bed of Denman, but every time they flew over the canyon – they couldn’t see it in the radar data,” Morlighem told BBC News. “Older maps suggested a shallower canyon, but that wasn’t possible; something was missing,” says Morlighem.

Morlighem points out that BedMachine will help reduce the uncertainty in sea level rise projections from numerical models. He adds that future bed topography mapping on land could be greatly enhanced by charting seafloor depth offshore and beneath floating ice, which is an area of active study right now.

BedMachine Antarctica is publicly available through the National Snow and Ice Data Center in Boulder, Colorado.