It’s business as usual at the Petermann glacier, doing what a glacier does, calving ice into the sea. We reported on another chunk in 2010, four Manhattans in size. Borrowing from an oft used media ploy, at this rate, it will be down to ice cube size in ten years. I wonder though, if we’d ever have noticed any of this without MODIS? Keep that in mind when reading the claims.
From the University of Delaware — An ice island twice the size of Manhattan has broken off from Greenland’s Petermann Glacier, according to researchers at the University of Delaware and the Canadian Ice Service. The Petermann Glacier is one of the two largest glaciers left in Greenland connecting the great Greenland ice sheet with the ocean via a floating ice shelf.
Andreas Muenchow, associate professor of physical ocean science and engineering in UD’s College of Earth, Ocean, and Environment, reports the calving on July 16, 2012, in his “Icy Seas” blog. Muenchow credits Trudy Wohleben of the Canadian Ice Service for first noticing the fracture.
The discovery was confirmed by reprocessing data taken by MODIS, the Moderate Resolution Imaging Spectroradiometer aboard NASA’s Terra and Aqua satellites.
At 46 square miles (120 square km), this latest ice island is about half the size of the mega-calving that occurred from the same glacier two years ago. The 2010 chunk, also reported by Muenchow, was four times the size of Manhattan.
“While the size is not as spectacular as it was in 2010, the fact that it follows so closely to the 2010 event brings the glacier’s terminus to a location where it has not been for at least 150 years,” Muenchow says.
“The Greenland ice sheet as a whole is shrinking, melting and reducing in size as the result of globally changing air and ocean temperatures and associated changes in circulation patterns in both the ocean and atmosphere,” he notes.
Muenchow points out that the air around northern Greenland and Ellesmere Island has warmed by about 0.11 +/- 0.025 degrees Celsius per year since 1987.
“Northwest Greenland and northeast Canada are warming more than five times faster than the rest of the world,” Muenchow says, “but the observed warming is not proof that the diminishing ice shelf is caused by this, because air temperatures have little effect on this glacier; ocean temperatures do, and our ocean temperature time series are only five to eight years long — too short to establish a robust warming signal.”
The ocean and sea ice observing array that Muenchow and his research team installed in 2003 with U.S. National Science Foundation support in Nares Strait, the deep channel between Greenland and Canada, has recorded data from 2003 to 2009.
The Canadian Coast Guard Ship Henry Larsen is scheduled to travel to Nares Strait and Petermann Fjord later this summer to recover moorings placed by UD in 2009. These mooring data, if recovered, will provide scientists with ocean current, temperature, salinity and ice thickness data at better than hourly intervals from 2009 through 2012. The period includes the passage of the 2010 ice island directly over the instruments.
According to Muenchow, this newest ice island will follow the path of the 2010 ice island, providing a slow-moving floating taxi for polar bears, seals and other marine life until it enters Nares Strait, the deep channel between northern Greenland and Canada, where it likely will get broken up.
“This is definitely déjà vu,” Muenchow says. “The first large pieces of the 2010 calving arrived last summer on the shores of Newfoundland, but there are still many large pieces scattered all along eastern Canada from Lancaster Sound in the high Arctic to Labrador to the south.”
Prior to 2010, the last time such a sizable ice island was born in the region was 50 years ago. In 1962, the Ward Hunt Ice Shelf, on the northern coast of Ellesmere Island in Nunavut, Canada, calved a 230-square-mile island.
Article by Tracey Bryant
“While the size is not as spectacular as it was in 2010, the fact that it follows so closely to the 2010 event brings the glacier’s terminus to a location where it has not been for at least 150 years,” Muenchow says.
From the two images posted here it seems like the point of rupture in relation to the land is very similar to point where the Manhatten x4 chunck broke off. However, if we can expect the delta of ice on towards the right bank to break up in a similar way to the previous calving, the terminus would seem to have moved back about 5km.
Also since the new break can be seen forming at that time, we can also estimate how far the glacier has advanced since the 2010 event: roughly 5km. So about half of area that has broken off is due to advancment of the glacier the other half is recession of the terminus.
So it would be more accurate to say that the Peterman galicier has lost one Manhatten not two.
Assuming that the advancment of the glacier has not slowed dramatically in this period (alarmists suggest basal melting should be accelerating not slowing advancment), the last calving would have been a loss of 4-1=3 Manhattens.
The recession of the glacier is now about one third of what it was just two years ago.
I spy with my beady eye….
lots more (thinn) sea ice in the 2012 picture and lots more open water in the 2010 picture
which does NOT suggest warmer seas, but the opposite, and we know that glacier calving is not primarily caused by warmer air.
And and the ice shelf is now wider in 2012 with peripheral open sea areas to each side being reduced.
It’s also appears that the land based ice sheet has withdrawn considerably between the two graphs shown but despite the reflectance scale being the same I note the colour code of that glacier itself has lightened considerably.
The 2010 graph has a much wider range of reflectance values, both at the deep blue and the red end of that scale.
Has someone been “correcting” the MODIS calibration in the mean time?
@ur momisugly Andreas Muenchow says:
July 17, 2012 at 9:32 pm
Thank you for your courteous involvement here, at this blog. Your opinions will be politely received. Thanks again.
In this Welsh view of the glacier (http://www.aber.ac.uk/greenland/Petermann.shtml) there are two adjacent pictures of the glacier taken in 2009 and 2011 which show the nature of the ice at the glacier terminus in late summer. The video points out that the ice loss is 25 times greater from the underside than the top, so changes in air temperature have a relatively minor impact (note also the snow-covered ground at either side of the channel – not a lot of melting there).
Given that the glacier is effectively anchored at the two sides to the cliffs then I would expect flexing of the central portion due to tides, the weather and the fact that the body of the glacier is pushing forward at approx 1km per year to induce stress fractures which would lead to break up, but I have seen no discussion of these effects as contributors, simply references to temperatures of air and sea. As with all alarmist outpourings, there seems to be a lot of blinkered supposition here and not a lot of fact.
David Ross said
Apart from the fact that 1962 cannot by any measure be called “pre-AGW”, you probably refer to the “Ellesmere Ice Shelf”, which was encompassing about 3,500 square miles (9,100 km2) has been in place for approximately 3,000 years until the second half of the 20th century, when it broke into 6 pieces, of which the Ward Hunt Ice Shelf was the largest at about 155 square miles (400 km2) in size.
Ward Hunt itself remained stable until in April 2000, satellite images revealed that a large crack in the ice had begun to form, and in 2003, it was announced that the ice sheet had split completely in two in 2002.
It’s been breaking up in smaller pieces ever since.
I thought that summer brought an increase in iceberg numbers.
Not a glacier, but an ice-shelf. Air temperature has very little effect on ice, its heat capacity is too low; water temperature can and does have an effect. In any case, glaciers transport ice to lower altitudes where it can melt, or in this case, float away. It’s what they do, part of the water cycle. Alarmists might just as well throw up their hands at rivers discharging into the sea – they’re doing exactly the same job, though at a much faster rate.
The Peterman Glacier continues to advance.
How about another Arctic sea ice update? If I’m not mistaken, the last time I read anything here was when the ice extent was almost equal to the average of the past decades. How is the ice doing now? Is it still recovering?
OMG! We all need a drink. Manhattans anyone?
GREEN-land,
‘Nuff said
As was noted by another commenter, the glacier has clearly extended further into the sea prior to the break off of the calf. Looking at the image, I had the distinct impression that it’s growing, not shrinking – oops my bad, couldn’t possibly grow with CAGW.
Yes, but only 1/26th the size of Rhode Island – the gold standard in size-comparators.
Global warming is inaccurate. And any climate scientist worth his or her salt knows it. That some other climate scientists use this tread-worn statistic speaks volumes and not well of them. There are many areas of the globe that are experiencing cooling. Are you saying they do not exist?
Hmmm – the side-by-side images are slightly different sizes and unaligned at the bottom. The picture on the right needs to be resized in proportion to align with the bottom of the image on the left. Just a nitpik for whoever created it.
“Vanity of vanities; all is vanity.”
Maybe the authors should review the science of Ecclesiastes (slightly revised to note that glaciers can be rivers of ice):
“All the ice rivers run into the sea; yet the sea is not full: unto the place from whence the ice rivers come, thither they return again.”
“There is no new thing under the sun.”
Thank you for your post Andreas, very scientific and precise. I only wish more scientists were as exact as you seem to be and also as forthcoming. Thanks very much
Rob Dekker wrote:
“1962 cannot by any measure be called “pre-AGW”
I wrote “pre-CAGW” i.e catastrophic climate change. The warmists generally do not portray the 60’s as an era of climate catastrophes. Whereas now it seems that every extreme climate/weather related event is portrayed as a man-made catastrophe. I have no doubt this will be the case on the alarmisphere for this calving event.
Dekker also wrote:
“you probably refer to the “Ellesmere Ice Shelf” ”
No “probably” about it. I drew my example and data entirely from the last paragraph of the above article (maraschino cherries etc, aside).
“Prior to 2010, the last time such a sizable ice island was born in the region was 50 years ago. In 1962, the Ward Hunt Ice Shelf, on the northern coast of Ellesmere Island in Nunavut, Canada, calved a 230-square-mile island.”
I merely rephrased Bryants example in terms of Manhattans.
Andreas Muenchow says:
July 17, 2012 at 9:32 pm
Could you tell us what you know about the ice thickeness. Also any speculation as to what triggered the break–apart from gradual melting. Thanks, –AGF
I blame Greenland’s problems on the excessive use of helicopters and icebreakers by those studying it. If someone will give me a huge grant I will show a very strong correlation between the number of researchers/film makers/NGOs belching out CO2 in Greenland and the 0.11C+/-0.025C per annum temperature rise in the area.
Sounds Titanic. Hope the vikings didn’t hit any during the medieval warming period.
Peter Plail says:
July 18, 2012 at 1:31 am
From your link it would seem that Greenpeace run part of the University of Aberystwyth (or use it as a means of controlling the research output of the relevant part of the university).
Yes, Bob , I’ll take a manhatten. Definitely on the rocks with extra large ice cubes!
jono1066 says:
July 18, 2012 at 12:46 am
I spy with my beady eye….
lots more (thinn) sea ice in the 2012 picture and lots more open water in the 2010 picture
which does NOT suggest warmer seas, but the opposite, and we know that glacier calving is not primarily caused by warmer air.
The Calving in 2010 occurred in early August rather than mid-July so the sea-ice in the mouth of the glacier had three more weeks or so to disperse in 2010. The partial crack which led to this break is apparent in 2010 and hasn’t advanced very much since then.
Anthony: “I wonder though, if we’d ever have noticed any of this without MODIS? Keep that in mind when reading the claims.”
Probably the same way that they were noticed pre-satellite, damn big ice islands showing up downstream. This link describes the discovery of ice islands in photoreconnaissance flights during the 40s and 50s:
http://pubs.usgs.gov/pp/p1386j/iceshelves/iceshelves-hires.pdf
They’re hard to miss:
A Petermann fragment a year later (2011) off Newfoundland:
http://earthobservatory.nasa.gov/IOTD/view.php?id=52178