Today
I went to see the documentary “Chasing
Ice” which I can recommend to all.
Here
is a trailer for the movie.
and an article from the Extreme Ice Survey which is responsible for the scientific work in recording the rapid retreat of the Greenland (and other) icebergs.
Greenland
Melting
Greenland’s massive ice sheet is melting this summer
like never before. Warm temperatures have conspired to thaw parts of
the island — including 97 percent of its surface ice, temporarily —
at unprecedented rates
31
July, 2012
The
signs are everywhere. On July 11, meltwater from upstream of
Kangerlussuaq, west Greenland, spectacularly washed out a bridge.
Videos show the Watson River overwhelming
the bridge and tossing
a tractor as
if it were a child’s toy.
On
the same day, the Summit camp in central Greenland was in the midst
of a record four-day
stretch with
temperatures above freezing. At more than 10,000 feet above sea
level, Summit is usually the coldest and driest place in Greenland.
But as warm air washed over it, snow began to melt, waterlogging
researchers’ boots and making it impossible for resupply planes to
land on the once-frozen runways. The last time Summit melted like
this was in 1889, ice
cores show.
On average, these island-wide melts happen about once every 150
years.
So
where did the warm air come from? According to NASA,
ridges of warm air have been passing over Greenland since late May.
An even warmer one began moving onto the island on July 8. By July 12
it had melted nearly all of Greenland’s surface ice, according to
remote-sensing microwave and radar data
This
kind of widespread thaw has never been seen in the satellite era,
NASA says. An atmospheric pressure pattern known as the North
Atlantic Oscillation set
the stage for
more warm air to flow along the west coast of Greenland. At the same
time, Greenland’s ice has been getting darker, thanks to a
combination of factors such as more bright snow melting away every
year as well as changes in snow grain shape and size that end up
absorbing more sunlight. A new
scientific paper,
to appear in The
Cryosphere,
even predicted before the July thaw that total surface melt could
happen over Greenland within a decade.
Summit
and other areas refroze after the warm air moved away. But in the
long term Greenland’s ice is still vanishing. Its outlet glaciers,
which flow into the sea and thus directly contribute to sea level
rise, have
been speeding up.
Its ice sheet, overall, has been losing mass at an
ever-faster rate.
And melt rates for June and July 2012 across Greenland far outstrip
melt rates from previous years — including the record
set in 2010,
according to Marco
Tedesco of
the City College of New York.
Computer
modeling by Tedesco and Xavier Fettweis of the University of Liège
suggests that two regions are particularly sensitive to rising global
surface temperatures. The first of those is southwest Greenland,
along which warm air can easily be circulated. The second is
northwest Greenland, which is especially influenced by thinning and
shrinking Arctic sea ice. (Sea ice coverage has been tracking at
levels far
below average through
July. Melting began earlier than normal through most of the Arctic.)
Indeed,
northwest Greenland is where the summer’s latest meltdown took
place. On July 16, a chunk of ice twice the size of Manhattan broke
off the
Petermann glacier, which two years ago had calved another huge
iceberg.
Hoping
to catch such events as they happen, the Extreme Ice Survey installed
two time-lapse cameras above Petermann in 2011. But it will take an
$80,000 helicopter ride to retrieve the cameras and get a close-up
look at what really happened. For now, Petermann is keeping its
secrets.
Greenland:
Petermann glacier calves huge iceberg - interactive
Watch
as an iceberg twice the size of Manhattan breaks free from
Greenland's massive Petermann glacier
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