An international team of researchers funded by NASA and the National Science Foundation (NSF) will travel to one of Antarctica's most active, remote and harsh spots to determine how changes in the waters circulating under an active ice sheet are causing a glacier to accelerate and drain into the sea.
expedition will be the most extensive ever deployed to Pine Island Glacier. It
is the area of the ice-covered continent that concerns scientists most because
of its potential to cause a rapid rise in sea level. Satellite measurements
have shown this area is losing ice and surrounding glaciers are thinning,
raising the possibility the ice could flow rapidly out to sea.
multidisciplinary group of 13 scientists, led by Robert Bindschadler, emeritus
glaciologist of NASA's Goddard Space Flight Center in Greenbelt,
Md., will depart from the McMurdo Station in Antarctica in mid-December, and spend six weeks on the
ice shelf. During their stay, they will use a combination of traditional tools and
sophisticated new oceanographic instruments to measure the shape of the cavity
underneath the ice shelf and determine how streams of warm ocean water enter
it, move toward the very bottom of the glacier and melt its underbelly.
project aims to determine the underlying causes behind why Pine Island Glacier
has begun to flow more rapidly and discharge more ice into the ocean," says
Scott Borg, director of NSF's Division of Antarctic Sciences, the group that
coordinates all U.S. research in Antarctica. "This could have a
significant impact on global sea-level rise over the coming century."
have determined the interaction of winds, water and ice is driving ice loss
from the floating glacier. Gusts of increasingly stronger westerly winds push
cold surface waters away from the continent, allowing warmer waters that
normally hover at depths below the continental shelf to rise. The upwelling
warm waters spill over the border of the shelf, and move along the sea floor,
back to where the glacier rises from the bedrock and floats, causing it to
salty waters and fresh glacier melt water combine to make a lighter mixture
that rises along the underside of the ice shelf, and moves back to the open
ocean, melting more ice on its way. How much more ice melts is what the team
wants to find out, so it can improve projections of how the glacier will melt
and contribute to sea-level rise.
2008, Bindschadler was the first person to set foot on this isolated corner of Antarctica as part of initial reconnaissance for the
expedition. Scientists had doubted it was even possible to reach the
crevasse-ridden ice shelf. Bindschadler used satellite imagery to identify an
area where helicopters could land safely to transport scientists and instrumentation
to and from the ice shelf.
Pine Island Glacier ice shelf continues to be the place where the action is
taking place in Antarctica," Bindschadler
says. "It only can be understood by making direct measurements, which is
hard to do. We're doing this hard science because it has to be done. The
question of how and why it is melting is even more urgent than it was when we
first proposed the project over five years ago."
will use a hot water drill to make a hole through the ice shelf. After the
drill hits the ocean, the scientists will send a camera down into the cavity to
observe the underbelly of the ice shelf and analyze the seabed lying
approximately 1,640 feet below the ice. Next, the team will lower an instrument
package provided by oceanographer Tim Stanton of the Naval
in Monterrey, Calif., into the hole. The primary
instrument, called a profiler, will move up and down a cable attached to the
seabed, measuring temperature, salinity and currents from approximately 10 feet
below the ice to just above the seabed.
hole will support a similar instrument array fixed to a pole stuck to the
underside of the ice shelf. This instrument will measure how ice and water
exchange heat. The team also will insert a string of 16 temperature sensors in
the lowermost ice to freeze inside and become part of the ice shelf. The
sensors will measure how fast heat is transmitted upward through the ice when
hot flushes of water enter the ocean cavity.
Anandakrishnan, a geophysicist with Pennsylvania
in University Park, Pa., will study the shape of the ocean
cavity and the properties of the bedrock under the Pine Island Glacier ice
shelf through a technique called reflective seismology, which involves
generating waves of energy by detonating small explosions and banging the ice
with instruments resembling sledgehammers. Measurements will be taken in about
three dozen spots using helicopters to move from one place to another.
International Team to Drill beneath Massive Antarctic Ice Shelf
December 6, 2011