PINE ISLAND GLACIER
ANTARCTICA
Dee Finney's blog
start date July 20, 2011
today's date November 28, 2012
page 388
TOPIC: PINE ISLAND, ANTARCTICA - GLACIER CRACKED
Richard A. Lovett
for National
Geographic News
Published February 2, 2012
With a gargantuan crack slowly splitting it apart,
Antarctica's fastest-melting glacier is about to lose a chunk of ice
larger than all of New York City, scientists say.
(Also see
"Manhattan-Size Ice Island Cracks in Half.")
The crevasse stretches 19 miles (30 kilometers) long and up to 260 feet
(80 meters) wide, as shown in a
picture taken by
NASA's Terra satellite in October and featured this week as a
NASA Image of the Day.
Snaking across the floating tongue of the Pine Island Glacier in West
Antarctica, the crack is expected to create an iceberg 350 square miles (907
square kilometers)—versus 303 square miles (785 square kilometers) for
Manhattan, Brooklyn, Queens, Staten Island, and the Bronx combined,
according to
NASA.
As for when the iceberg might shove off, "that is very difficult to
predict," said oceanographer
Eric Rignot of
NASA's Jet Propulsion Laboratory, "but in the coming months for sure."
Glacier "Contributing Most to Sea Level"
Usually there's nothing extraordinary about a glacier calving, said
glaciologist Ted
Scambos of the National Snow and Ice Data Center (NSIDC) in Boulder,
Colorado.
Glaciers that flow into the sea, like the Pine Island Glacier, go through
a normal cycle in which the floating section grows, stresses mount, and an
iceberg breaks off, Scambos said.
"That is nothing unusual in most cases."
But when the pattern deviates, glaciologists take notice. In this case,
the crack is forming significantly farther "upstream" than has previously
been the case. That "signifies that there are changes in the ice," he said.
When "that point of rifting starts to climb upstream, generally you see
some acceleration of the glacier." That means that the ice will flow into
the ocean at a
faster rate, contributing even more to sea level rise.
(Related:
"Hundreds of Glaciers Melting Faster in Antarctica.")
Such an acceleration is of particular concern at the Pine Island Glacier,
because, among Antarctic glaciers, it's "the one that's contributing the
most to sea level rise."
In fact, he said, ice flows from that glacier alone account for a quarter
to a third of Antarctica's total contribution to sea level rise.
"It's moving at about three kilometers [almost two miles] per year,"
Scambos said. And, he noted, "it's been accelerating quite a bit."
(Pictures:
Antarctica Warming.)
Cracking Glacier "Really Important"
As far as sea levels are concerned, changes in the Pine Island Glacier
and other West Antarctic glaciers are far more important than shifts among
the continent's other glaciers, such as East Antarctica's Mertz
Glacier—despite Mertz's much publicized release of a
Luxembourg-size iceberg in early 2010.
That's because the
"Luxembourg" iceberg came from a glacial ice tongue that had just been
"sitting there," said oceanographer
Doug
Martinson of Columbia University's Lamont-Doherty Earth Observatory.
By contrast, "West Antarctica has ice streams, of which Pine Island is
one. Those are fast-flowing streams of ice," said Martinson, who specializes
in polar oceans.
When ice breaks off the Pine Island Glacier, he said, more ice can flow
in faster from the mountains above—ice that will eventually wind up
contributing to sea level rise.
"This glacier," NSIDC's Scambos added, "is really important."
LARSEN ICE SHELF
A stark white lobe of a glacier advances across Antarctica's
dry valleys region,
so called because of its scarcity of snow. Earth's fifth-largest continent
contains
more than two-thirds of the world's freshwater in the form of ice, yet some
areas
receive less than two inches (five centimeters) of precipitation a year
Gentoo penguins on the shore - Antarctica - Cierva Cove
Other types of penguins here are Adelie, Rockhopper,
Chinstrap, and Emporer
National Geographic calls this melting to be caused by Global
Warming
This is on the edge of Larsen Ice Shelf
The Larsen Ice Shelf is a long, fringing
ice shelf
in the northwest part of the
Weddell
Sea, extending along the east coast of
Antarctic Peninsula from
Cape
Longing to the area just southward of
Hearst Island. Named for Captain
Carl Anton Larsen, the master of the
Norwegian whaling vessel
Jason,
who sailed along the ice front as far as 68°10' South during December 1893.[1]
In finer detail, the Larsen Ice Shelf is a series of three shelves that
occupy (or occupied) distinct embayments along the coast. From north to south,
the three segments are called Larsen A (the smallest), Larsen B, and Larsen C
(the largest) by researchers who work in the area. The Larsen A ice shelf
disintegrated in January 1995.[2]
The Larsen B ice shelf disintegrated in February 2002. The Larsen C ice shelf
appeared to be stable in 2008, though scientists predict that, if localized
warming continues at its current rate, the shelf could disintegrate at some
point within the foreseeable future.[3]
The Larsen disintegration events were unusual by past standards. Typically,
ice shelves lose mass by
iceberg
calving
and by melting at their upper and lower surfaces. The disintegration events are
linked to the ongoing
climate warming in the
Antarctic Peninsula, about 0.5 °C per decade since the late 1940s, which is
a consequence of localized warming of the Antarctic peninsula.[4]
This localized warming is caused by
anthropogenic
global warming, according to some scientists through strengthening of the
Antarctic annular winds.[5]
Clear
view of
the
Antarctic
Peninsula,
the
Larsen
Ice
Shelf,
and
the
sea
ice covered waters
around
the region.
Some of the Antarctica ice shelves
During 31 January 2002–7 March 2002
the Larsen B sector collapsed and broke up, 3,250 km²
of ice 220 m thick disintegrated, meaning an ice shelf covering an area
comparable in size to
the US state
of
Rhode
Island collapsed in a single season.[6]
Larsen B was stable for up to 12,000 years, essentially
the entire
Holocene
period since
the last glacial period, according to
Queen's University researchers.[7]
By contrast, Larsen A "was absent for a significant part
of that period and reformed beginning about 4,000 years ago," according
to the
study.
Despite its great age,
the Larsen B was
clearly in trouble at
the time
of
the
collapse. With warm currents eating away
the underside
of
the
shelf, it had become a "hotspot
of global warming."[8]
What especially surprised glaciologists was
the speed
of
the
breakup, which was a mere three weeks (or less). A factor
they had not anticipated was
the powerful effects
of liquid water; ponds
of meltwater formed on
the surface during
the near 24 hours
of daylight in
the summertime,
then
the water flowed down into cracks and, acting like a multitude
of wedges, levered
the shelf apart, almost in one fell swoop.[9][10]
Global increase in air temperature was not
the only factor contributing to
the break according to
Ted Scambos,
of
the
University
of Colorado's national snow and ice data centre.
It's likely that melting from higher ocean temperatures, or even a
gradual decline in
the ice mass
of
the peninsula over
the centuries, was pushing
the Larsen to
the brink
Although
the remaining Larsen C region, which is
the furthest
south, appears to be relatively stable for now,[12]
continued warming could lead to its breakup within
the next decade.[13]
If disintegration should occur with this last major sector, which is larger in
size than
the US states
of
New
Hampshire and
Vermont combined —
then
the enormous Larsen Ice Shelf
viewed in 1893 by Carl Anton Larsen and his crew aboard
the Jason will largely be gone in just over a century after
its discovery.
The
collapse
of Larsen B has revealed a thriving
chemotrophic ecosystem 800 m (half a mile) below
the sea. "Despite near freezing and sunless conditions, a community
of clams and
microbial mats are flourishing in undersea
sediments.
[...]
The discovery was accidental.
U.S.
Antarctic Program
scientists
were in
the northwestern Weddell Sea investigating
the sediment record in a deep glacial trough twice
the size
of
Texas.
Methane and
hydrogen sulfide associated with
cold seeps
is suspected as
the source
of
the
chemical energy powering
the ecosystem.
The area had been protected by
the overlying ice sheet from debris and sediment which was seen to be
building up on
the white microbial mats after
the breakup
of
the
ice sheet.
The clams were observed clustered about
the vents.[14]
Studies show that in
the middle
of
the
present
interglacial
the former Larsen A region, which was
the furthest
north and outside
the
Antarctic Circle, had previously broken up and reformed only about 4,000
years ago, although
the former Larsen B had been stable for at least 10,000 years.[7]
The maximal ice age on
the current shelf dates from only two hundred years ago.
The speed
of
Crane
Glacier increased threefold after
the collapse
of
the
Larsen B and this is likely to be due to
the removal
of a buttressing effect
of
the
ice shelf.[15]
Recent data collected by an international team
of investigators through satellite-based radar measurements suggests that
the overall ice-sheet mass balance in
Antarctica is increasingly negative.[16]
See also
References
-
^
U.S. Geological Survey Geographic Names Information System: Larsen Ice
Shelf
-
^
Scientists Trek to Collapsing Glaciers to Assess
Antarctica’s Meltdown and Sea-Level Rise July 16, 2012
Scientific American
-
^
Larsen C thinning
-
^
Connor, Steve (2005) "Ice shelf collapse
was biggest for 10,000 years since Ice Age"
The Independent, London (Aug 4),
online
-
^
Marshall et al.,
"The
Impact
of a Changing Southern
Hemisphere Annular Mode on
Antarctic Peninsula Summer Temperatures",
Journal
of Climate, vol. 19, pp. 5388–5404, October
2006.
-
^
Hulbe, Christina (2002) "Larsen Ice
Shelf 2002, warmest summer on record leads to disintegration" website
of Portland State University,
online
- ^
a
b
Press Release (2005) "Ice Shelf
disintigration threatens environment, Queen's study" Queens University,
Kingston, Ontario,
online on
American Association for
the Advancement
of Science's Eurekalert
-
^
Pearce, Fred (2006)
The Last Generation: How Nature Will Take Her Revenge for Climate
Change, Eden Project Books, p. 92
-
^
Larsen B Ice Shelf Collapses in
Antarctica
-
^
Antarctic Ice Shelf Collapse Triggered By Warmer Summers
Office
of News Services,
University
of Colorado at Boulder, Jan. 16, 2001
-
^
"Experts challenge ice shelf claim". Two scientists have
claimed that climate change was not
the only cause
of
the collapse
of a 500bn tonne ice shelf in
Antarctica six years ago. BBC News. 7 February 2008.
http://news.bbc.co.uk/2/hi/uk_news/wales/mid_/7231372.stm.
Retrieved 2008-02-07.
-
^
Riedl C, Rott H, Rack W (2004)
"Recent Variations
of Larsen Ice Shelf,
Antarctic
Peninsula, Observed by Envisat" Proceedings
of
the 2004 Envisat & ERS Symposium, Salzburg, Austria,
online
-
^
Rignot, Eric (2007) "Mass Balance and
Ice Dynamics
of
Antarctic Peninsula Glaciers for IPY2007-2008" Proposal #359,
International Polar Year Expression
of Intent,
online
-
^
Domack,
Eugene; Scott Ishman, Amy Leventer, Sean Sylva, Veronica Willmott, Bruce
Huber (19 July 2005).
"A Chemotrophic Ecosystem Found Beneath
Antarctic Ice Shelf". Eos, Transactions American
Geophysical Union (American Geophysical Union) 86 (29).
Bibcode
2005EOSTr..86..269D.
doi:10.1029/2005EO290001.
http://www.agu.org/pubs/crossref/2005/2005EO290001.shtml.
Retrieved July 19, 2012.
-
^
Rignot, E.;
Casassa, G.; Gogineni, P.; Krabill, W.; Rivera, A.; Thomas, R. (2004).
"Accelerated ice discharge from
the
Antarctic Peninsula following
the collapse
of Larsen B ice shelf".
Geophysical Research Letters 31 (18): L18401.
Bibcode
2004GeoRL..3118401R.
doi:10.1029/2004GL020697.
http://www.glaciologia.cl/textos/RignotetalGRLPeninsulaAccel.pdf.
Retrieved 2011-10-22.
edit
-
^
Perlman, David (2008) "Antarctic
Glaciers Melting More Quickly" San Francisco Chronicle (January
26) p. A2,
online
External links
MORE ON ANTARCTICA
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www.greatdreams.com/solar/2009/space-weather-feb-2009.htm
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[PDF]
www.greatdreams.com/boeingwhistleblower-2010.pdf
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Quick View
NASA-funded
balloon-borne instrument high over Antarctica.
Researchers ... 124,000
feet above Antarctica using a helium-filled
balloon about as large as the ...
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It will help determine the worldwide
distribution of greenhouse gases, the
present status of the ominous hole in the
ozone layer over
Antarctica, and
the water
...
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UndoWhen I
was in
Antarctica I saw cores like
this and the guy looked at it. He said right
here is where the US Congress passed the
Clean Air Act. I
...
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scientists have been increasingly able to
document melting and the discovery of
icebergs breaking off from
Antarctica
in recent years,
...
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AURORAS AT THE SOUTH POLE: On June 10th, a
solar wind gust hit Earth's magnetic field,
causing the skies over
Antarctica
to turn green.
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1935 Karoline Mikkelson- First woman to set
foot on
Antarctica. Margaret Mead (
1901-1978)
- U.S. anthropologist renowned for her
studies on gender and ...
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: MAGNETIC POLE SHIFT - A NEW NORTH STAR..
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is where a telescope to observe incoming approach of
this giant is being observed. N is about 3 to 4 times
size of earth.
-
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UndoWHAT'S ALL THIS
ABOUT LAKE VOSTOK IN
ANTARCTICA? ADMIRAL BYRD -
OPERATION
HIGHJUMP NEW SCHWABENLAND.
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Evidence for abrupt climate change is readily found in
ice cores taken from Greenland and
Antarctica.
One of the best known examples of such an event is the
...
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Undo-90 F/-68 C The
edge of
Antarctica reaches Rio de Janeiro
Minnesotans migrate to Wisconsin thinking it MUST be
warmer. -100 F/-73 C Santa
...
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The Indonesian quake struck just three days after an 8.1
quake struck the ocean floor between Australia and
Antarctica, causing buildings to shake hundreds of
...
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UndoThere were no ice
sheets during the PETM, whereas Earth currently has
enough ice in Greenland and
Antarctica to raise
sea levels by more
...
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and Bolivia shattered record cold temps and were colder
than
Antarctica for much of July, killing
millions of fish, and many
...
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These experiments are based on finding a prehistoric
“ice man” from
Antarctica whose DNA is
thousands of years more evolved than present day
humans'. Now
...
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Undo1995, Jul 7 Near
New York City 12. 1995, Dec 9 Cuenca, Ecuador 11. 1995,
Dec 22 1500 kilometres south of Argentina (
Antarctica)
>2 .
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The new missions are part of NASA's post-Columbia
program to send astronauts back to the moon to establish
a permanent
Antarctica-style research station
...
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eclipse is total, lasting up to 1 minute 57 seconds as
it sweeps across
Antarctica near the Amery Ice
Shelf. Partial phases
...
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in the seas around
Antarctica. Instead of
ending up in the Indian Ocean they veered eastward and
found themselves in the Pacific,
...
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UndoPalmer Station,
Antarctica, 76.38, 11:49.5, 18:29:26.5, P. San
Francisco, California, 77.95, 11:58.3, 18:29:35.3, P.
Los Angeles, California
...
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And then ended up in
Antarctica, or in
Schwabenland, and then died a few years ago in Brazil.
KC: That's what we heard. GG: I have all the documents
from our
...
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massive sliding.. the water will rise with the melting
but it won't be sudden. The contrails were seeded with
medicine by
...
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professional mountaineering guide in Bellingham who, for
years, has been recovering meteorites in
Antarctica
for scientific study.
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www.greatdreams.com/solar/space-weather.htm
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The next two: Feb 28, 2009, over
Antarctica and
Apr. 22, 2009, over North America. The North American
occultation is going to be good, occuring in a lovely
...
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UndoWhether it turns
out to be Osama Bin Laden, the Afghanis, the
Palestinians, the Iraqis, the penguins of
Antarctica
or the Bavarian Illuminati,
...
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confirmed meteorites, most of them found in remote
places like the Sahara Desert or
Antarctica.
Perhaps the most famous of the Martian
...
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result into a balloon flight in 40 km altitude over
Antarctica in January 2008. SUNRISE will for the
first time allow observations
...
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eastern Indian Ocean; the end visible in Australia,
Antarctica, New Zealand, Asia except extreme
northern part, eastern Africa,
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Undo4-24-2001 - WHY
ARE 12 CREWMAN BEING EVACUATED FROM
ANTARCTICA
AT THE RISK OF MANY OTHER LIVES? SOMETHING IS COMING
...
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coming towards earth, changing trajectory and speed -
and hordes of scientists are rushing down to
Antarctica to see what this thing is.
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UndoThese clones have
been produced in secret underground Cabal factories in
Iceland,
Antarctica and elsewhere. The clones
have been
...
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who insist in placing Atlantis and/or Lemuria in the
Polar Regions of
Antarctica and the Arctic
against common sense and
...
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Undo1995, Dec 22 1500
kilometres south of Argentina (
Antarctica) >2.
1996, Jan 15 2000 kilometres south of New Zealand >3.
1996, Mar 26 West of
...
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UndoSea ice is floating
and, unlike the massive ice sheets anchored to bedrock
in Greenland and
Antarctica, doesn't affect
ocean levels. However
...
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UndoSep 11, 2001 –
Whether it turns out to be Osama Bin Laden, the
Afghanis, the Palestinians, the Iraqis, the penguins of
Antarctica or the
...
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www.greatdreams.com/blog-2012-2/dee-blog259.html
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Undo2009); January 5 –
Franck Montagny, French Formula One driver; January 7 –
Emilio Palma, Argentine citizen, first human born in
Antarctica ...
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UndoCook almost
encountered the mainland of
Antarctica, but
turned back north towards Tahiti to resupply his ship.
He then resumed his southward
...