Researchers Provide Detailed Picture of Ice Loss Following Collapse of Antarctic Ice Shelves
An international team of researchers has combined data from multiple sources to provide the clearest account yet of how much glacial ice surges into the sea following the collapse of Antarctic ice shelves.
The work by researchers at the University of Maryland, Baltimore County (UMBC), the Laboratoire d’Etudes en Géophysique et Océanographie Spatiales, Centre National de la Recherche Scientifique at the University of Toulouse, France, and the University of Colorado’s National Snow and Ice Data Center, Boulder, Colo., details recent ice losses while promising to sharpen future predictions of further ice loss and sea level rise likely to result from ongoing changes along the Antarctic Peninsula.
The Larsen B ice shelf began disintegrating around Jan. 31, 2002. Its eventual collapse into the Weddell Sea remains the largest in a series of Larsen ice shelf losses in recent decades, and a team of international scientists has now documented the continued glacier ice loss in the years following the dramatic event. NASA’s MODerate Imaging Spectroradiometer (MODIS) captured this image on Feb. 17, 2002. (Credit: MODIS, NASA’s Earth Observatory) › Larger image
“Not only do you get an initial loss of glacial ice when adjacent ice shelves collapse, but you get continued ice losses for many years — even decades — to come,” says Christopher Shuman, a researcher at UMBC’s Joint Center for Earth Systems Technology (JCET) at NASA’s Goddard Space Flight Center, Greenbelt, Md. Shuman is lead author of the study published online July 25 in the Journal of Glaciology. “This further demonstrates how important ice shelves are to Antarctic glaciers.”
An ice shelf is a thick floating tongue of ice, fed by a tributary glacier, extending into the sea off a land mass. Previous research showed that the recent collapse of several ice shelves in Antarctica led to acceleration of the glaciers that feed into them. Combining satellite data from NASA and the French space agency CNES, along with measurements collected during aircraft missions similar to ongoing NASA IceBridge flights, Shuman, Etienne Berthier, of the University of Toulouse, and Ted Scambos, of the University of Colorado, produced detailed ice loss maps from 2001 to 2009 for the main tributary glaciers of the Larsen A and B ice shelves, which collapsed in 1995 and 2002, respectively.
The Landsat Image Mosaic of Antarctica (LIMA) provides this “flyover” view of the Larsen Ice Shelf’s long reach out into the Weddell Sea. (Credit: LIMA)
“The approach we took drew on the strengths of each data source to produce the most complete picture yet of how these glaciers are changing,” Berthier said, noting that the study relied on easy access to remote sensing information provided by NASA and CNES. The team used data from NASA sources including the MODerate Imaging Spectroradiometer (MODIS) instruments and the Ice, Cloud and land Elevation Satellite (ICESat).
The analysis reveals rapid elevation decreases of more than 500 feet for some glaciers, and it puts the total ice loss from 2001 to 2006 squarely between the widely varying and less certain estimates produced using an approach that relies on assumptions about a glacier’s mass budget.
The authors’ analysis shows ice loss in the study area of at least 11.2 gigatons (11.2 billion tons) per year from 2001 to 2006. Their ongoing work shows ice loss from 2006 to 2010 was almost as large, averaging 10.2 gigatons (10.2 billion tons) per year.
An animation showing ice edge changes for the Larsen B ice shelf and its adjacent tributary glaciers can be viewed at http://svs.gsfc.nasa.gov/goto?3803.
Related Links
› Larsen B Ice Front Changes 2001-2009 (NASA SVS)
› Animation of Larsen B collapse (NASA Earth Observatory)
› Before and after Larsen A comparison (NASA SVS)
Goddard Release No. 11-046
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UPDATE: The press liaison at NSDIC wrote to complain about the “worse than we thought” title.
Dear Mr. Watts,
We noted that you republished a NASA/NSIDC press release regarding a new Journal of Glaciology paper. In the headline of your post, the phrase “worse than we thought” is in quotation marks. This makes it appear as if it is a quote from the press release, and a statement by the researchers. We request that you remove the quotation marks so that it is clearer that this is your headline.
NASA and NSIDC scientists are always willing to grant interviews to journalists if you have questions about their research.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Katherine Leitzell Science Communications National Snow and Ice Data Center Cooperative Institute for Research in Environmental Sciences 449 University of Colorado Boulder, CO 80309
I replied:
Dear Ms. Leitzell
The “worse than we thought” is a cliché that reverberates through the climate science community and is well understood by my readers. It is a satirical statement, intending to convey the oft repeated science by press release position that climate change is an escalating series of alarming press releases, each worse that the other.
Quotation marks also serve to delineate a satirical statement, and is often visualized in person by the person taking two fingers (index and middle) and bending them. It has also been described as being a snowclone in the vein of.
X is “worse than we thought”.
Thus, since satire is protected by free speech, and this is a fair use application of a publicly funded study and press release, the headline stands. I will however make a footnote at the bottom of the story stating that NSIDC has complained, and the title are my satirical words. You should know that the press release is not being well received. http://tomnelson.blogspot.com/2011/07/antarctic-ice-allegedly-declining-at.html
Thank you for your consideration.
Anthony Watts
Dave Wendt says:
July 27, 2011 at 4:17 pm
There are so many elements in the attempted calculation of GMSL which are either unknown, inadequately modeled or neglected that the whole project is an exercise in statistical folly.
The British Admiralty charts are the best record of sea levels over the past 250 years. We sailed Tonga and Fiji with charts drawn by William (mutiny) Bligh in the 1700’s. The charts were accurate to within a foot of depth, in an area with very small tides (that might cause observational errors).
Most of the BA charts were drawn 2 centuries ago and have not been resurveyed. They show the location of drying and awash rocks all over the globe. Everywhere I’ve sailed in the Pacific and Indian oceans, when the old charts show a rock too shallow to sail over, it is still too shallow to sail over.
If sea level rise was happening anything like the hype, these charts would all show datum corrections for water depth. They show the lat/long corrections made possible/necessary by satellites and GPS. But no depth correction. This tells me that sea levels have not risen enough in 200 years to be of interest to mariners, who every day rely on the depth of water for their safety.
So, you are worried about beach front property for an event (water rise of 1.5 meters, maybe) that “might” happen – if nothing changes between now and the future – in a future that is more than 450 year away?
And for this you want to destroy the world’s economy and kill millions, and cause an early death from poverty, starvation, disease, malnutrition, and bad water for tens of billions other innocents?
Just so you can “feel good” about CO2 levels now?
@- ferd berple says:
July 27, 2011 at 6:52 pm
“The paleo records show that even with significant warming, we are looking at ten thousand years to melt these ice sheets, not the 100 year fiction that alarmists like Gore envision. ”
Gore is not a climate scientists and hasn’t made any predictions of sea level in 100 years.
The paleo records show that during the A1 melt pulse ~13,000BPE melting resulted in sea level rise of around a foot per year, 100 times the rise rate seen at present. During the Eemian interstadial when temperatures were very slightly higher, sea levels had also risen above present levels by at least 10 feet within a thousand years.
It is because the paleo record shows the much faster melting and sea level rise in the past it is difficult to refute the possibility that present rates of sea level rise might increase ten-fold.
izen says:
July 27, 2011 at 11:23 pm
“It is because the paleo record shows the much faster melting and sea level rise in the past it is difficult to refute the possibility that present rates of sea level rise might increase ten-fold.”
I could have won the Powerball jackpot tonight. I even had a ticket. But guess what, it didn’t happen. You can’t refute the fact that it sure was possible though.
izen says:
July 27, 2011 at 11:23 pm
It is because the paleo record shows the much faster melting and sea level rise in the past it is difficult to refute the possibility that present rates of sea level rise might increase ten-fold.
That level of melting can only occur after an ice age, such as the beginning of our current interglacial, the Holocene.
Interestingly, toward the end of the last ice age, there was a 1,500 warm period, followed by a sharp drop called the Younger Dryas, during which the earth was plunged back into ice age conditions, which occurred in the space of about 100 years. If you need something to worry about, worry about the possibility of that happening again.
You people need to get it into your thick skulls that it is in fact cooling, not warming, which is dangerous to man, and indeed to all life.
izen says:
July 27, 2011 at 11:23 pm
“It is because the paleo record shows the much faster melting and sea level rise in the past it is difficult to refute the possibility that present rates of sea level rise might increase ten-fold.”
Can refute the possibility on present observed temperatures during the current interglacial, when most of the ice has already melted from the major ice age. The logic of these temperatures in Antarctic over the next century, when these are far too cold to melt ice on the continent during summer. (Even a 5c average increase there wouldn’t be enough) Only the ice in contact with relatively much warmer sea is melting in Western Antarctica, move to the coast and just inland a little and it stays well below zero in mid-summer.
How can sea level rise ten-fold when the ice melting is already on shelves lower than the sea level and part of the sea? Even areas with glaciers where temperatures reach above zero for example in Greenland, still can gain mass when the winter precipitation exceeds the melt during summer. In relation to a continent that is well below zero during summer, there is no chance of this happening and is just alarmist thinking. Therefore just relying on Greenland to cause this ten-fold increase with any glaciers actually melting on land (unlike Antarctic, exception parts of the Peninsula) closer to the coasts during summer. The problem being the volume of water from these is not big enough, unless the melting suddenly increases ten-fold. How is this even remotely possible with most of central Greenland remaining below zero during summer?
See the update I added to the story body in response to NSIDC