Category Archives: Ice Island

Icebergs, Islands, and Instruments off Isle de France, North-East Greenland

Andreas Muenchow

Leaving all land behind when FS Polarstern sailed for Greenland almost 2
weeks ago, we saw land again for a few hours last Sunday. A small
ice-capped island called Isle de France was ahead of us. Solid ice was to
the west, open water to the east, and Greenland proper appeared just
faintly above the western horizon. We arrived at 5 am in the morning, but
the northern summer light changes more with the clouds, absent this day,
than it does as day becomes night. We are more than 1000 km to the north
of the Arctic Circle and about half-way between Bremerhaven and the North
Pole.

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Waiting for the mooring work to begin, we sailed along a row of large
and grounded tabular icebergs and ice islands that appeared strung out
like pearls on a line where the ocean’s water was about 100 meters deep.
Sea- and ice-scape looked the same eons ago when massive ice-sheets
covered much of northern Europe and North-America before people invented
agriculture and turned from nomadic hunters and gatherers to settled
farmers and peasants. And while everyone awake admired Greenland’s beauty
and serenity that Sunday morning, I had only one thought: Here go my
moorings.
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The ship paused for a few hours to wait for me and Jonathan to ready
instruments that we needed to placed on the ocean floor. They are
designed to measure ocean currents for the next 2-3 years and will give
us better ideas on how ocean heat and currents melt
Greenland’s glaciers from below. We already had deployed four such
instruments the day before out of sight of land and icebergs. Now we were off Isle de France to complete our shelf mooring program with 3
instruments placed across the south-western slope of Norske Ore Trough.

ModisMoorBath

This ‘trough” is really a broad and deep submarine valley that connects
the deep Fram Strait 150 km to the east to Greenland’s largest glaciers
100 km in the West and North. The valley may act as a pathway, so we
think, to move warm ocean waters from Fram Strait near the bottom across
the broad and confused continental shelf of Greenland. It is coastal oceanography that we do, but the heat that our coastal flows
transport towards the glaciers does impact a changing climate that
changes land, sea, and icescape both here around Greenland and
elsewhere as ocean sea level rises when ice on land becomes ice on water
and eventually water in the ocean.

As fast-flowing floating glaciers disappear, such as Zachariae Isstrom did
the last 10 years, the ice-sheet behind them on land often accelerates and
thins because ice-shelves attached to glaciers act a little like a cork
does to a bottle of Champagne. The bubbly inside exerts a high pressure
against the cork separating the Champagne from the lower pressure outside,
especially if shaken. If you loose the cork or remove it explosively, then
the bubbly will spill out quickly. The friction of an ice-shelf may have
retarded the advancement of the ice-sheet behind in a subtle balance of
forces. Now, as the ice shelf is removed, a new
balance of forces will have to establish itself. The transition from one
to another stable state usually occurs via accelerations: The glacier
speeds up, stretches, and as it stretches, it thins and may allow the sea
water to advance deeper shoreward to melt more ice that was before not
in contact with the ocean. It is a positive feedback and the potential
exists, that the glacier keeps retreating faster as a result. Both
Jacobshavn Glacier in South-West Greenland and Pine Island Glacier in
Antarctica do this now.

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But I digress and want to return to Isle de France with its pearl string
of tabular icebergs within about 5 km off our first moorings. At 170
meters below the surface a strike by one of these stunning mountains and
islands of hard ice will perhaps wipe out a mooring, but perhaps the
goddess of the sea will steer the perhaps 50,000 year old towers of ice into shallow
water where they will ground for a few years. Either way, I will be
watching these icy islands from afar for the next few years in what
becomes a most exciting and pleasurable puzzle with many pieces. Some may
fit and some may be missing. Perhaps the best we can hope for is
a sketch or an outline. Control of nature is vanity, we are merely
temporary sailors on a mighty ocean with ice that will last longer than
either us or whatever sensor we may place in her ways.

posted by Pat Ryan for Andreas Muenchow

Petermann Ice Island Breaks while Plowing into the Bottom

The Manhattan-sized ice island that last year broke free of Petermann Gletscher in North Greenland plowed into the bottom and broke apart. Force equals mass times acceleration. When 18 giga tons (mass) of moving ice crashes into the ocean’s bottom 200 meters below the surface (acceleration), then something gotta give. And give it did, Continue reading

Petermann Ice Island visited by Vagabond

An ice-cube with a mass of 18 giga tons left Petermann Gletscher in the summer of 2012 and thus became PII-2012 for Petermann Ice Island 2012. The CCGS Henry Larsen visited and surveyed the waters, bottom, and ice of the fjord that same year. Since then PII-2012 traveled 300 km southward, grounded in shallow water, but continued its voyage south a month or so again. Last thursday it was visited by a 47′ sail boat called “Vagabond.” I just discovered the report by its Master Eric Brossier, Continue reading

Land-Fast Ice Cover off North Greenland: Will NASA bite?

When a large outlet glacier of North Greenland (Petermann Gletscher) discharged an ice island four times the size of Manhattan in August of 2010, the United States’ Congress held formal inquiries on its cause within days of the event. Congressmen, scientists, and the global media speculated that this event and concurrent severe droughts in Russia and floods in Asia were tied to record-breaking air temperatures and global warming. Reviewing available data, Johnson et al. (2011) cautioned that most melting of floating ice shelves such as Petermann Gletscher is dominated by physical ocean processes below, not above the ice (Reeh, 2001, Rignot and Steffen, 2008). The National Journal asked me to write an essay to answer the question: “Is Climate Change Causing Wild Weather?” which I answered with a nerdy No, but …. Motivated by questions asked during the congressional hearing, I showed that waters in Petermann Fjord (a) originate from the Arctic Ocean to the north, (b) contain heat of Atlantic origin, and (c) have warmed significantly since 2003 (Muenchow et al., 2011).

Petermann Gletscher from MODIS Terra. Repeat NASA along-glacier flight tracks are shown in the left and middle panels. White line across the glacier are ICESat tracks. Thick black line across the glacier near y = 0 km is the grounding line location from Rignot and Steffen (2008). Dark areas within 2 km off the western wall are mountain shadows.

Petermann Gletscher from MODIS Terra. Repeat NASA along-glacier flight tracks are shown in the left and middle panels. White line across the glacier are ICESat tracks. Thick black line across the glacier near y = 0 km is the grounding line location from Rignot and Steffen (2008). Dark areas within 2 km off the western wall are mountain shadows.

When I reported here that the same glacier discharged yet another ice island in July 2012, this one “only” twice the size of Manhattan, I was not so sure anymore, that this was merely another extreme event caused by natural processes. Continue reading

Petermann Photos, Places, and People

Petermann Gletscher sent off Manhattan-sized islands of ice in 2010 and 2012 that now litter the eastern seaboard of Canada from its farthest northern Ellesmere Island to its farthest eastern Newfoundland. The ice is streaming south along thousands of miles within icy Arctic waters. Petermann Gletscher itself is flat, hard to grasp by the naked eye, its endless expanse of white vanishes into the horizon when we look towards the Greenland Ice Sheet ALONG the glacier:

North-eastern section of Petermann Glacier on Aug.-11, 2012, the meandering river is the centerline, view is almost due east. [Photo Credit: Canadian Coast Guard Ship Henry Larsen.]

North-eastern portion of Petermann Glacier on Aug.-11, 2012, the meandering river is the centerline, view is almost due east with Kap Fulford and Kap Agnes on the left center and Daugaard Jensen Land in the background on the right. [Photo Credit: Canadian Coast Guard Ship Henry Larsen.]

Next, lets look ACROSS Petermann from roughly the same latitude. This perspective is more dramatic as vertical cliffs give shape, cliffs are cut by smaller side-glaciers. More specifically, we see the CCGS Henry Larsen helicopter flying down Belgrave Glacier as we look across Petermann which flows from the Greenland Ice Sheet on the left out to sea on the right. On the other (south-western) side we see Faith Glacier in the background about 10 miles away.

Seaward front of Petermann Glacier Aug.-11, 2012. View is from a small side-glacier towards the south-east across Petermann Fjord with Petermann Gletscher to the left (east). [Photo Credit: Erin Clarke, Canadian Coast Guard Ship Henry Larsen]

Seaward front of Petermann Glacier Aug.-11, 2012. View is from a small side-glacier (Belgrave Gl.) towards a similar glacier (Faith Gl.) across Petermann Fjord with Petermann Gletscher flowing from the left out to sea on the right. [Photo Credit: Erin Clarke, Canadian Coast Guard Ship Henry Larsen]

Contrasting large Petermann Gletscher, the many smaller glaciers on both its sides evoke drama as ice plunges down from 3000 feet above in a rage of forms, colors, and shapes. These side glaciers have their own side glaciers that sometimes rival the Alpine glaciers in Europe, Asia, and the Americas that most of us are more familiar with.

Some side glaciers have names, but they are rarely seen on maps and charts. The side glaciers are mapped, but photos are hard to find. Flying over them last year, I was utterly lost. Reviewing photos now, I remember people, smells, computer troubles, and exciting ocean discoveries. Nevertheless, I am hard pressed to place the places we saw on a map or name them. Distances are deceiving, the air is clean and 50-80 miles of visibility are common. A moment later, I cannot see the other side of the ship as we are suddenly in clouds and fog. Everything is always in motion, the ice, the water, the ship, the clouds, all of this without strong reference points like the exit or distance signs on a Turnpike, Interstate, or Autobahn.

Northern Kennedy Channel near the entrance to Petermann Fjord with Kap Morton in cloud banks. [Credit: Andreas Muenchow]

Northern Kennedy Channel near the entrance to Petermann Fjord with Kap Morton in cloud banks. [Credit: Andreas Muenchow]

And along comes Espen Olsen, a frequent contributor to Neven’s Arctic Sea Ice blog and forums, and discovers a plethora of names that I can check, google, and use to remember expeditions to Petermann over the last 10 years with many good friends. So with his help and that of other explorers like Lauge Koch, Tony Higgins, and the collected wisdom of the U.S. Defense Mapping Agency, I labeled some prominent glaciers and capes on an Aug,-21, 2012 MODIS-Terra image that I constructed from data that NASA provide to anyone free of charge. I chose this image and time, because the 2012 ice island is already in Nares Strait and thus out of sight:

Names of glaciers, capes, islands in Petermann Region over MODIS of Aug.-21, 2012.

Names of glaciers, capes, islands in Petermann Region over MODIS of Aug.-21, 2012.

Espen tells me that his Danish sources are protected by copyright (I still like to cite them), but the aviation maps of the U.S. military are in the public domain and can be downloaded from the University of Texas in Austin Library, e.g.,

Petermann Gletscher and surroundings extracted from U.S. Defense Mapping Agency Chart ONC A5 (January 1991).

Petermann Gletscher and suroundings extracted from U.S. Defense Mapping Agency Chart ONC A5 (January 1991).

while the modified version of Figure-2 from Dr. Tony Higgins 1990 publication is available at the Alfred Wegener Institute. Nevertheless, it should only be used for non-profit educational purposes or as a reference:

Petermann Gletscher extend and topography from 1953 through 1978 (from Higgins, 1990) with 2012 terminus position drawn in by hand.

Petermann Gletscher extend and topography from 1953 through 1978 (from Higgins, 1990) with 2012 terminus position drawn in by hand.

With all these details out-of-the-way, we can now start placing photos into places and add names to them. Perhaps others like Espen Olsen can write or edit Wiki entries or correct the false latitude and longitudes that populate the many databases that provide such information on the web. Over the next weeks and months I will try to post as many photos of Petermann’s natural beauty along with an evolving MODIS map that names and shows places. Here are just a few teasers without further comment except what’s in the captions.

The merging of Sigurd Berg and Hubert Glaciers which discharge into Petermann Gletscher on its eastern wall. The view is landward towards the north-east as the helicopter flies in from Petermann. [Credit: Barbara O'Connell, Canadian Coast Guard]

The merging of Hubert (left) and Sigurd Berg (right) Glaciers which discharge into Petermann Gletscher on its eastern wall. The view is landward towards the north-east as the helicopter flies in from Petermann. [Credit: Barbara O'Connell, Canadian Coast Guard]

Petermann Gletscher and Fjord in Aug.-2012. View is to the north-west with Faith Glacier (top left) and Kap Lucie Marie (top right) showing the western wall of Petermann. [Photo Credit: CCGS Henry Larsen]

Petermann Gletscher and Fjord in Aug.-2012. View is to the north-west with Faith Glacier (top left) and Kap Lucie Marie (top right) showing the western wall of Petermann. [Photo Credit: CCGS Henry Larsen]

Looking down Belgrave Glacier discharging into Petermann Gletscher at its terminus in Aug. 2012 [Credit: CCGS Henry Larsen]

Looking down Belgrave Glacier discharging into Petermann Gletscher at its terminus in Aug. 2012 [Credit: CCGS Henry Larsen]

Higgins, A.K. (1990). Northern Greenland glacier velocities and calf ice production Polarforschung, 60, 1-23 Other: 0032-2490