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From the National Science Foundation and staff reports
A U.S.-led international team of scientists has created
the first detailed picture of a rugged mountain range
buried under more than 4 kilometers of ice in East Antarctica.
The researchers, based in two field camps on the high-altitude
polar plateau, used twin-engine light aircraft to conduct
an aerogeophysical survey of roughly 2 million square
kilometers of the ice sheet, the equivalent of two trips
around the globe.
The team also established a network of seismic instruments
across an area the size of Texas.The instruments provide
information on the structure of the mantle and crust beneath
the mountains to learn more about the history of the subglacial
range. The researchers suspect the mountain range served
as the nucleation point for the massive East Antarctic
Ice Sheet.
“Working cooperatively in some of the harshest conditions
imaginable, all the while working in temperatures that
averaged minus 30 degrees Celsius, our seven-nation team
has produced detailed images of [the] last unexplored
mountain range on Earth,” said Michael Studinger,
of Columbia University’s Lamont-Doherty Earth Observatory
, in a press release from the National Science Foundation
(NSF) .
“As our two survey aircraft flew over the flat white
ice sheet, the instrumentation revealed a remarkably rugged
terrain with deeply etched valleys and very steep mountain
peaks,” added Studinger, the co-leader of the U.S.
portion of the Antarctica's Gamburstev Province (AGAP)
project.
The initial AGAP findings raise additional questions
about the role of the Gamburtsevs in birthing the East
Antarctic Ice Sheet, which extends over more than 10 million
square kilometers atop the bedrock of Antarctica, said
geophysicist Fausto Ferraccioli, of the British Antarctic
Survey (BAS) , who led the U.K. science team.
“We now know that not only are the mountains the
size of the European Alps but they also have similar peaks
and valleys,” he said. “But this adds even more
mystery about how the vast East Antarctic Ice Sheet formed.”
“If the ice sheet grew slowly, then we would expect
to see the mountains eroded into a plateau shape. But
the presence of peaks and valleys could suggest that the
ice sheet formed quickly — we just don't know,”
he added. “Our big challenge now is to dive into
the data to get a better understanding of what happened”
millions of years ago.
The initial data also appear to confirm earlier findings
that a vast aquatic system of lakes and rivers exists
beneath the ice sheet of Antarctica, a continent that
is the size of the United States and Mexico combined.
“The radar mounted on the wings of the aircraft
transmitted energy through the thick ice and let us know
that it was much warmer at the base of the ice sheet,”
explained Robin Bell , also of Lamont Doherty and co-leader
of the U.S. team.
The scientists are particularly interested in the effect
the subglacial aquatic system has on the dynamics of ice
sheets, because the presence of water lubricates the ice
and speeds its flow. That’s a key parameter in nailing
down predictions on future sea-level rise.
The most recent report of the Intergovernmental Panel
on Climate Change (IPCC) said that it is difficult to
predict how much the vast ice sheets of Greenland and
Antarctica will contribute to sea-level rise because so
little is known about the behavior of the ice sheets.
Estimates from various sources say the seas could go up
my more than a meter at century’s end, which could
cause massive coastal flooding.
The data also will be used to help locate where the world’s
oldest ice is located, possibly for a future ice-coring
project. Scientists estimate the ice at the bottom of
the ice sheet could be 1 million years old. The oldest
ice core recovered to date is about 800,000 years old.
The AGAP discoveries took place during fieldwork in December
and January, near the official conclusion of the International
Polar Year (IPY) , the largest coordinated international
scientific effort in five decades. Ceremonies marking
the conclusion of IPY fieldwork took place in Geneva,
Switzerland on Feb. 25.
NSF is the lead U.S. agency for IPY, and it manages all
federally funded research on the southernmost continent
through the U.S. Antarctic Program (USAP) . It provided
much of the complex logistical support that made the discoveries
possible. NSF also supported U.S. researchers from Columbia
University , Washington University in St. Louis , Pennsylvania
State University , the Center for Remote Sensing of Ice
Sheets (CReSIS) at the University of Kansas , the U.S.
Geological Survey (USGS) and the Incorporated Research
Institutions in Seismology (IRIS) .
AGAP was fully in the spirit of IPY, noted Detlef Damaske
of Germany’s Federal Institute for Geosciences and
Natural Resources , as no one nation could have done it
alone. The effort required teams of scientists, engineers,
pilots and support staff from Australia, Canada, China,
Germany, Japan, the U.K. and the United States to pool
their knowledge, expertise and logistical resources to
deploy two survey aircraft, equipped with ice-penetrating
radar, gravimeters and magnetic sensors as well as the
network of seismometers.
Bell noted that AGAP is “emblematic of what the
international science community can accomplish when working
together.”
While the planes made a series of survey flights, covering
a total of 120,000 square kilometers, the seismologists
flew to 26 different sites using Twin Otter aircraft equipped
with skis, to install scientific equipment that will run
for the next year on solar power and batteries.
The seismology team — from Washington University,
Penn State, IRIS, and Japan’s National Institute
of Polar Research — also recovered 10 seismographs
that have been collecting data since last year over the
dark Antarctic winter at temperatures as low as minus
73 degrees Celsius.
“The season was a great success,” said Douglas
Wiens , of Washington University in St. Louis. “We
recovered the first seismic recordings from this entire
part of Antarctica ... Now, we are poring over the data
to find out what is responsible for pushing up mountains
in this part of Antarctica.”
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