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[music] It's a long, 12-hour day,
flying out of Chile to one of the farthest points Operation IceBridge
can reach in the Antarctic, the Getz Ice Shelf.
We know from satellite measurements that this 300 mile long floating ice shelf
is losing mass, but with IceBridge data we hope to find out something
about why and how fast this ice is disappearing.
After crossing the windy Drake Passage
at high altitude we descend and are treated to a tour
of Antarctic ice in almost all its forms. We see different kinds of
sea ice, from thin gray sheets to solid fields covered
in snow and littered with icebergs.
We see gigantic tabular icebergs, taller than a house
and longer than a runway, that were once part of the largest
piece of ice on Earth. And we see the ice sheets themselves,
smooth in some areas, heavily crevassed in others.
As we arrive at the survey area,
we come across the calving front of Getz Ice Shelf.
This 10-storey-tall face is currently
where mighty icebergs break off into the ocean.
Upstream a crack is forming,
threatening to calve off a new tabular iceberg and move the
calving front inland. Even from just a few thousand feet above,
the scale is deceiving. The crack looks like something you could jump across,
but our laser data tells us it’s 45 meters deep
and with our digital photography we can estimate the width at more than a dozen meters.
But back to why we’re here.
We need to get a better handle on the bathymetry below the ice shelf,
basically the shape of the ocean floor below this floating
ice tongue. The shape will help us calculate the circulation
of the warm water … well, comparatively warm water
that’s eating away at the ice shelf from below.
Our gravity meter, or gravimeter, actually senses the mass of rock
below the ocean, giving us a picture of the grounding line, where the ice sheet
leaves the support of land and begins to float on the water.
But that’s all on the marine side. We also need to understand what’s happening inland.
Our laser data tells us how much the surface of the ice shelf
is lowering. And our ice-penetrating radar tells us the shape
and elevation of the bedrock below the ice, which helps us estimate
how much ice will flow into the water, and how fast.
On the inland side we pass by a ridge in Marie Byrd Land.
Most of the distinctive mountains peaking through the thick ice here
are extinct volcanoes from the Cenozoic era. They’re a welcome scenic
change from the wide flat landscape that covers so much of polar regions.
After collecting nearly 5 hours of data,
we head for home, and get a rare clear view of the
Antarctic Peninsula, with its stunning mountain chain and almost Alpine glaciers.
Out the port side of our DC-8 we
watch the sun set at its incredibly slow polar pace,
cross the Strait of Magellan, and prepare to land back in Chile
well after dark.
[music]