Scientists
from the U.S., U.K. and Australia have used ice-penetrating radar to
create the first high- resolution topographic map of one of the last
uncharted regions of Earth, the Aurora Subglacial Basin, an immense
ice-buried lowland in East Antarctica larger than Texas.
The
map reveals some of the largest fjords or ice cut channels on Earth,
providing important insights into the history of ice in Antarctica. The
data will also help computer modelers improve their simulations of the
past and future Antarctic ice sheet and its potential impact on global
sea level.
“We
knew almost nothing about what was going on, or could go on, under this
part of the ice sheet and now we’ve opened it up and made it real,”
said Duncan Young, research scientist at The University of Texas at
Austin’s Institute for Geophysics and lead author on the study, which
appears in this week’s journal Nature.
“We
chose to focus on the Aurora Subglacial Basin because it may represent
the weak underbelly of the East Antarctic Ice Sheet, the largest
remaining body of ice and potential source of sea-level rise on Earth,”
said Donald Blankenship, principal investigator for the ICECAP project, a
multinational collaboration using airborne geophysical instruments to
study the ice sheet.
Because
the basin lies kilometers below sea level, seawater could penetrate
beneath the ice, causing portions of the ice sheet to collapse and float
off to sea. Indeed, this work shows that the ice sheet has been
significantly smaller in the past.
ICECAP team at McMurdo Station, Antarctica. Standing: Ray Cameron, Mike McCrae and Steve Kaiser (Kenn Borek Air); Martin Siegert (Edinburgh), Duncan Young (Texas), Andrew Wright (Edinburgh); Scott Kempf, Donald Blankenship, Gonzalo Echerverry (Edinburgh). On the ground: Jack Holt; Jamin Greenbaum; Dusty Schroeder; and Isaac Smith. Photo: Jack Holt. |
Previous
work based on ocean sediments and computer models indicates the East
Antarctic Ice Sheet grew and shrank widely and frequently, from about 34
to 14 million years ago, causing sea level to fluctuate by 200 feet .
Since then, it has been comparatively stable, causing sea-level
fluctuations of less that 50 feet. The new map reveals vast channels cut
through mountain ranges by ancient glaciers that mark the edge of the
ice sheet at different times in the past, sometimes hundreds of
kilometers from its current edge.
“We’re
seeing what the ice sheet looked like at a time when Earth was much
warmer than today,” said Young. “Back then it was very dynamic, with
significant surface melting. Recently, the ice sheet has been better
behaved.”
However,
recent lowering of major glaciers near the edge detected by satellites
has raised concerns about this sector of Antarctica.
Young
said past configurations of the ice sheet give a sense of how it might
look in the future, although he doesn’t foresee it shrinking as
dramatically in the next 100 years. Still, even a small change in this
massive ice sheet could have a significant effect on sea level.
Scientists at The University of Texas at Austin’s Institute for
Computational Engineering and Sciences, and at Australia’s Antarctic
Climate and Ecosystems CRC are developing models that will use the new
map to forecast how the ice sheet will evolve in the future and how it
might affect sea level.
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This
research is part of ICECAP (Investigating the Cryospheric Evolution of
the Central Antarctic Plate), a joint project of The University of Texas
at Austin’s Jackson School of Geosciences, the University of Edinburgh
and the Australian Antarctic Division. For three field seasons, the team
flew an upgraded World War II-era DC-3 aircraft with a suite of
geophysical instruments to study the ice and underlying rock in East
Antarctica.
Funding
for this research is provided by the National Science Foundation
(U.S.), the National Aeronautics and Space Administration (U.S.), the
Natural Environment Research Council (U.K.), the Australian Antarctic
Division, the G. Unger Vetlesen Foundation (U.S.), the Antarctic Climate
and Ecosystems CRC (Aus.), and the University of Texas at Austin’s
Jackson School of Geosciences (U.S.).
