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Posted at 10:45 AM ET, 08/23/2010

Greenland's new ice island slides toward the sea

By Andrew Freedman

* From showery to sensational: Full Forecast | NatCast *


NASA satellite image of the ice island (top-left quadrant of image) that recently broke off the floating ice shelf of the Petermann Glacier in northwest Greenland. Credit: NASA.

Earlier this month we helped break news of a huge new ice island that calved off Greenland's Petermann Glacier. (That followed the story from earlier this summer that a major chunk of Greenland's Jakobshavn Glacier broke off as well). So, if you're like me, you may have a few nagging questions in the back of your mind right now:

Where did that ice island -- which is about 40 percent larger than the District of Columbia -- go? Did it break up altogether? Is it roaming the North Atlantic, awaiting collision with a ship, Titanic style? Or is it floating up the Potomac, ready to wreak havoc on the Lincoln Memorial?

Ok, so that last question is ridiculous. Nevertheless, the fact that a massive ice island broke off Greenland, only to disappear from the news cycle, is rather unsettling.

Fortunately, the folks at NASA have answered my first question by recently publishing the above satellite image of the area that gave birth to the new island.

It turns out that the new ice island -- the largest chunk of ice to break off the Petermann Glacier since 1962, having taken one quarter of the glacier's 40-mile long floating ice shelf with it -- is slowly making its way down a fjord in Northwest Greenland, toward the Nares Strait.

The image above, taken Aug. 16, shows that some pieces of ice have loosened around the edges of the island, which has rotated since calving off the glacier. The glacier itself can be seen in the lower right part of the image, looking longingly at the huge piece of its former self... ("pining for the fjords", perhaps?)

According to NASA: "Thin longitudinal cracks appear on the ice island surface, and wider lateral cracks push in from the island's sides. An uneven line of pools, medium blue in color, runs down the length of the ice island."

Although Greenland's glaciers calve sizable icebergs each year, the chunk of ice that broke off the Petermann was unusually large. As CWG's Brian Jackson explained, the iceberg is more typical of the massive icebergs that calve off of Antarctic glaciers than glaciers in the Arctic.

It is unclear what role (if any) climate change may have played in this, as well as with the Jakobshavn event earlier this summer. In general, scientists have observed increased melting of the Greenland ice sheet in recent years through a variety of mechanisms, including warming ocean temperatures that can melt glaciers' floating ice shelves and speed up the transport of ice from land to sea.

For a more in-depth discussion of melting trends in Greenland, see my post from last month.

The views expressed here are the author's alone and do not represent any position of the Washington Post, its news staff or the Capital Weather Gang.

By Andrew Freedman  | August 23, 2010; 10:45 AM ET
Categories:  Climate Change, Freedman, Science  
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Comments

Hopefully it will float down to South Carolina and come to rest in Jim DeMint's front yard, where he can make another one of his idiotic igloos out of it.

Posted by: B2O2 | August 23, 2010 11:21 AM | Report abuse

Maybe it is just part of Slartibartfast's original design....

Posted by: erbele | August 23, 2010 11:52 AM | Report abuse

I wonder where Mr. Q. is...with his contrarian views on climate change. He would probably argue that glaciers in Greenland and Antarctica are continually calving off ice islands and icebergs.

He might also point out that we're going to be down in the seventies tomorrow--so much for global warming in 2010! Although Russia and eastern Siberia were warmer than normal this summer, north central Siberia seems to have been cooler than normal according to the climate map.

Posted by: Bombo47jea | August 23, 2010 12:00 PM | Report abuse

Looks like it is wedged.

Posted by: eric654 | August 23, 2010 3:16 PM | Report abuse

If the ice sheets floats over to Scotland, they can use it for scotch on the rocks (e.g., "ice is nice, but liquor is quicker").

I mean Greenland is melting away and some people are still in denial global warming? Maybe when folks can dive off the ledge of the Empire State Bldg. into the ocean they'll admit something is going on.

Posted by: JerryFloyd1 | August 23, 2010 5:08 PM | Report abuse

The Petermann Glacier is just doing what it does. It is growing, so it pushes ice out to sea a kilometer per year, and occasionally very big chunks break off.

In August 1991 the three pieces which calved had a combined area larger than the current iceberg. The chunk in 1962 was twice as big.

From the European space agency:

http://www.esa.int/esaEO/SEMYXY4OJCG_index_0.html#subhead2

Posted by: DonBishop | August 23, 2010 5:54 PM | Report abuse

DonBishop: Yes, calving happens (I can just see the t-shirt now). However, stating the Petermann is not "just doing what it does" gives the misleading impression that it is growing and shrinking equally: instead, every calving event is occurring further upstream.

Note that in the 9 years before this event, Petermann had already lost over 200 square kilometers: http://bprc.osu.edu/MODIS/. The rate of growth of the Petermann is being overwhelmed by the rate of loss from chunks falling off, both small and giant. The 34 widest Greenland glaciers had lost 1000 square kilometers from 2000 to 2009 (obviously this year will add a lot to that total).

And the same story globally: http://www.ncdc.noaa.gov/bams-state-of-the-climate/2009-time-series/?ts=glacier shows that the last year that had net global glacier growth was 1989, and it certainly looks like glacier loss is accelerating.

One calving event is like an anecdote: good for communication purposes, but not great data. But in this case, this photogenic symbol happens to accurately represents the regional and global patterns of glacier retreat that are (or, at least, "should be") undeniable.

-M

Posted by: marcusmarcus | August 23, 2010 6:42 PM | Report abuse

I suppose back in the 1300's there were Little Ice Age deniers who said the icing over of Greenland wasn't really happening or if it was, it wouldn't stay frozen forever. And they were right!

Posted by: eric654 | August 23, 2010 7:37 PM | Report abuse

so eric and marcus,
how fast do you think the onsets of the LIA and MWP were compared to the current warming?

Posted by: walter-in-fallschurch | August 24, 2010 9:59 AM | Report abuse

Walter, I've read history books and the LIA, even when not named, is much more dramatic than any change from cold to warm. Obviously the historians took notice of harsh winters and failed summer harvests. I've also been reading Fagan's "LIA". The onset of cooling was choppy, a few years of cooling, then a few years break, then back to cooling.

The real bottom line is all weather is local and dramatic warmups and cooldowns have always happened quickly here and there. The argument that today's warmup is worldwide is not supported by worldwide proxies on a statistical basis (some show dramatic increases like Briffa's Yamal, but most show a modest late 20th century increases). It's hard to use those proxies to judge past warmups either.

Perhaps past warmups were more uneven spatially and temporaly and therefore more "gradual". Sea levels were same or higher in the MWP, but again perhaps because of uneven warmth like a melted Greenland.

Posted by: eric654 | August 24, 2010 10:30 AM | Report abuse

The comments to this entry are closed.

 
 
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