Connecticut-sized ice shelf disintegrating in Antarctica

By: Dr. Jeff Masters , 10:48 PM GMT on March 25, 2008

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A large ice sheet on the Antarctic Peninsula has begun to disintegrate in spectacular fashion over the past four weeks, according to a press release today from the National Snow and Ice Data Center. They attribute the event to strong warming due to climate change. The victim is the Connecticut-sized Wilkins Ice Shelf (5,200 square miles), located about 1,000 miles south of the southern tip of South America. The nearby Larsen B Ice Shelf, which was about three times smaller than the Wilkins Ice Shelf, disintegrated in just three days in 2002. The Larsen B Ice Shelf was several thousand years old, and the Wilkins Ice Shelf is at least several hundred years old. It began disintegrating on February 28, and has just a narrow 6 km wide strip of ice holding it together.


Figure 1. Disintegrating ice from the Wilkins Ice Shelf forms huge blocks in the Bellingshausen Sea by the Antarctic Peninsula. Satellite image from March 8, 2008, courtesy of the National Snow and Ice Data Center.

Sea level rise due to antarctic melting
The disintegration of the Wilkins Ice Shelf will not significantly alter global sea level, since the ice is already floating in the ocean. Some Antarctic ice shelves are important because of their ability to insulate and buttress glaciers along the coast, and their loss allows more rapid melting of the glaciers they hold back. However, this is not the case for the Wilkins Ice Shelf. Its disintegration is of note because the shelf had been around hundreds of years, and is a spectacular sign that the climate is changing.

Melting of ice in the Antarctic Peninsula and along the ocean edges of the West Antarctic Ice Sheet is contributing to about 0.5 mm/year of sea level rise to the world's oceans, according to a NASA study published in February 2008. This is up from the 0.3 mm/year of sea level rise Antarctica contributed in 1996. Melting from the Greenland Ice Sheet also contributes about 0.5 mm/year to global sea level rise. Melting ice from Greenland and Antarctica each contribute about 10-15% of the observed 3-4 mm/year of global sea level rise.

Antarctic temperatures
While most of Antarctica cooled during the period 1981-2004, the Antarctic Peninsula where the Wilkins Ice Shelf lies warmed by about 1° C. Sea Surface Temperatures (SSTs) also warmed by about 1° C near the Antarctic Peninsula, and these warmer waters may be primarily responsible for the disintegration of the shelf. In the period 2005-2007, almost all of Antarctica warmed, canceling out much of cooling observed during 1981-2004 (Figure 2). I explained in detail in a November 2007 blog why most of Antarctica cooled up until the past few years.


Figure 2. Antarctic surface temperatures as observed via AHVRR satellite measurements between 1981 and 2007. Note that the Antarctic Peninsula where the Wilkins Ice Shelf lies has seen the strongest warming. Image credit: NASA

Jeff Masters

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331. SteveBloom
7:30 PM GMT on March 28, 2008
Re #329: Hadn't the lack of activity been more or less pinned to the dust blowing off the Sahara?
330. streamtracker
5:23 PM GMT on March 28, 2008
#271 Jer,

Reading through Pielka's post, it does nothing to address my and Steve's points.

Pileka's point seems to be a classic case of misdirection. As I stated before one is responding to processes that are long-term and other to short-term processes.

Member Since: October 24, 2005 Posts: 12 Comments: 1731
325. pottery
12:03 PM GMT on March 28, 2008

Busy day today. In and out.
Give praise children, give praise.
Member Since: October 24, 2005 Posts: 0 Comments: 24084
324. pottery
11:58 AM GMT on March 28, 2008
Good morning. It's 7:55 where I am, and we had 2 mm of rain earlier this morning. Nice, since I was putting out bush fires up to midnight last night.

Re: post 321, some stuff there that I would love to see Dr MASTERS and STORM W comment on.
Member Since: October 24, 2005 Posts: 0 Comments: 24084
323. SteveBloom
5:05 AM GMT on March 28, 2008
Re #319: Google "medi-cane storm" and you'll find a lot, including a blog post Jeff did. IIRC there's also a collection of sat photos somewhere, plus Kerry Emanuel did a paper on them. More are expected with additional warming.
322. streamtracker
3:17 AM GMT on March 28, 2008
OK, everybody who is trying to claim that seismic activity might have been responsible for the breakup, show us the seismic data. There are monitoring stations down there.
Did they register unusual activity on or around the date the ice broke off? And what accounts for the other ice shelves breaking off this decade. Shelves that had been stable for a very long time. Has there been unusual seismic activity over the last decade compared to the 1000's of years before when these shelves had been relatively stable?

There is a correlation between increase in rate of shelf breakup and increase in Antarctic temperatures. Has there also been a correlation between seismic activity and breakup?

Let's see the data.
Member Since: October 24, 2005 Posts: 12 Comments: 1731
321. Sunnyweathernot
2:07 AM GMT on March 28, 2008
I came across several articles during early
winter about upper atmospheric circulation and
how this affects weather. According to these
articles "upper atmospheric circulation patterns
have changed and increased in speed" although not
homogeneously.
If true, this could help explain some of the short
term changes in storminess over the last several years.
With increased upper atmospheric wind speeds we
would expect the following observable conditions:

1. Increase in winter Arctic ice but a maked decrease in summer ice.
2. More wind shear...more tornados, fewer hurricanes.
3. Increased Antarctic ice because of increased air outflow and speed
under much colder conditions than the Arctic.
4. In the northern hemisphere, snow in places much farther south than normal.
5. Lncreased wind speed in the Arctic which would more likely blow more
ice into the North Atlantic where it would more easily melt.

Granted climate and climate change is very complex. However, upper air
circulation is a topic I haven't seen very much information about and I am wondering
if this is a major factor in climate change. Also, if this has
been a factor in diminishing the number of hurricanse in the Atlantic the past couple years,
it doesn't mean it will this year. Certainly last year there were
major hurricanes where wind shear was low.
Member Since: March 17, 2008 Posts: 0 Comments: 3
320. Smyrick145
1:00 AM GMT on March 28, 2008
I don't blame you one bit with the last 2 seasons we've had.
Member Since: September 30, 2006 Posts: 0 Comments: 14
319. Stormchaser2007
1:00 AM GMT on March 28, 2008
I believe that the EURO govt should declare the Mediterranean sea a possible basin for subtropical storm development based on the fact that ive seen some storms in there that looked more "tropical" than Barry and other storms.
Member Since: June 9, 2007 Posts: 4 Comments: 15790
318. Stormchaser2007
12:55 AM GMT on March 28, 2008
I know that nova I was just saying that the radars arent picking up (if there are any) tornadoes right now.
Member Since: June 9, 2007 Posts: 4 Comments: 15790
317. Cavin Rawlins
12:54 AM GMT on March 28, 2008
Weak disturbance in the Central Mediterranean Sea just south of Italy. Image taken today at 1200 UTC.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
316. Drakoen
12:53 AM GMT on March 28, 2008
"Drakoen,
What are your thoughts on the upcoming hurricane season?"


Actually, I haven't really looked up on that. Also, I don't like making early predictions because they don't have much use but speculation.
Member Since: October 28, 2006 Posts: 57 Comments: 29927
315. Smyrick145
12:51 AM GMT on March 28, 2008
Drakoen,
What are your thoughts on the upcoming hurricane season?
Member Since: September 30, 2006 Posts: 0 Comments: 14
314. TerraNova
12:51 AM GMT on March 28, 2008
A storm does not necesarily have to have a TVS in order to be producing a tornado. Sometimes these radars fail to mark obviously tornadic storms with TVS's. These storms currently have several MESO signatures (the storm near Salem MO has one MESO marker on my radar view right now).
Member Since: July 30, 2007 Posts: 76 Comments: 4063
313. Stormchaser2007
12:50 AM GMT on March 28, 2008
2 spotter confirmed tornado reports have been posted along with a report of hail the size of base balls....
Member Since: June 9, 2007 Posts: 4 Comments: 15790
312. Stormchaser2007
12:45 AM GMT on March 28, 2008
7 tornado warnings up currently...none of them have a TVS though.
Member Since: June 9, 2007 Posts: 4 Comments: 15790
311. Drakoen
12:45 AM GMT on March 28, 2008
Good night everyone.
Member Since: October 28, 2006 Posts: 57 Comments: 29927
310. TerraNova
12:41 AM GMT on March 28, 2008
Storm label BO in Dent county MO has a 76 DBZ reading with 4 inch hail and impressive VIL.... now thats a dangerous storm

I posted an image of that storm earlier on...it's developed quite a bit more. Law enforcement is reporting that a tornado spawned by this cell touched down in Edgar Springs. Huge hail has also been reported:

A TORNADO WAS REPORTED IN EDGAR
SPRINGS WITH THIS STORM. GOLF BALL SIZE HAIL WAS REPORTED TO BE
COVERING THE GROUND IN THE CITY OF LENOX.
Member Since: July 30, 2007 Posts: 76 Comments: 4063
309. Cavin Rawlins
12:40 AM GMT on March 28, 2008
Very expansive outflow jet enhanced by an upper ridge over Western Australia

Member Since: July 24, 2005 Posts: 407 Comments: 19076
308. TerraNova
12:38 AM GMT on March 28, 2008
The first tornado report of the day is in:

COUNCIL HILL OK - TRAINED SPOTTERS REPORTED TORNADO 1 MILE NORTH OF COUNCIL HILL (TSA)
Member Since: July 30, 2007 Posts: 76 Comments: 4063
307. Stormchaser2007
12:36 AM GMT on March 28, 2008
Storm label BO in Dent county MO has a 76 DBZ reading with 4 inch hail and impressive VIL.... now thats a dangerous storm. Link
Member Since: June 9, 2007 Posts: 4 Comments: 15790
306. Ivansrvivr
12:32 AM GMT on March 28, 2008
Terra Nova that radar image looks like "chaff" to me.
305. LowerCal
12:31 AM GMT on March 28, 2008
re. #278
Antarctica seismically active?
Latest Earthquakes in the World - Past 7 days

Oh ... well that's only the past week! Just take a look at
Earthquake Hazards Program: Recent Earthquakes - Last 8-30 Days

Erm ... well there was a moderate earthquake last November.
Antarctic Earthquake, 5th November 2007 - John Seach (Vulcanologist)
Earthquakes in Antarctica are rare and the continent is generally earthquake free... The earthquake was not related to volcanic activity...
Member Since: July 26, 2006 Posts: 58 Comments: 9158
304. Cavin Rawlins
12:23 AM GMT on March 28, 2008
301. StormW 8:09 PM AST on March 27, 2008
Evening 456!


Evening to you too
Member Since: July 24, 2005 Posts: 407 Comments: 19076
303. Patrap
12:19 AM GMT on March 28, 2008
Nola / Houston ISS pass tonight. Heavens-Above Link

Groundtrack Link

The ATV will be one minute ahead of the ISS and dimmer. Link

ATV Groundtrack Link

Member Since: July 3, 2005 Posts: 421 Comments: 127636
302. TerraNova
12:13 AM GMT on March 28, 2008
There's a rather weird radar feature south and west of the keys...can anybody explain this? It doesn't appear to be normal precipitation.

Radar loop shows it better

Member Since: July 30, 2007 Posts: 76 Comments: 4063
299. Patrap
12:08 AM GMT on March 28, 2008
Bob Brookens Wins "Special Award" to be awarded AT the NHC Conference Awards Banquet,Thursday Link

The Barometer Bob Show for March 27, 2008! Link

Barometer Bob in the WRBN.Net Studio, Bob will talk about the National Hurricane Conferences we have attended, and the 30th Annual National Hurricane Conference for March 31 - April 4. He will be hosting a LIVE Remote Broadcast April 3, 2008 at Hooters of Pointe Orlando.
The show starts at 8pm/et and you can listen live at WRBN.Net

You can call into the show LIVE tonight at
1-866-931-8437(U.S.A Toll Free) or 904-259-4229 World Wide (Tolls Apply)
With your host Barometer Bob Brookens from Hurricane Hollow Weather!

Also,join us in "stormchat" during the show ,lotsa friends and Folks from all over.Link
Member Since: July 3, 2005 Posts: 421 Comments: 127636
298. Cavin Rawlins
12:06 AM GMT on March 28, 2008
Excellent TRMM Passes of Pancho



Member Since: July 24, 2005 Posts: 407 Comments: 19076
297. TerraNova
12:01 AM GMT on March 28, 2008
Is that from the GRlevelX software?

Yes; it's from the trial version of the GRLevel3 software. It's a great piece of equipment.
Member Since: July 30, 2007 Posts: 76 Comments: 4063
295. TerraNova
11:50 PM GMT on March 27, 2008
Thanks StormW! Good evening, by the way!
Member Since: July 30, 2007 Posts: 76 Comments: 4063
293. SafeInTexas
11:46 PM GMT on March 27, 2008
Hmm, looks like some severe weather is forming in Oklahoma. Have to see how this goes.
Member Since: September 19, 2005 Posts: 0 Comments: 64
292. TerraNova
11:46 PM GMT on March 27, 2008
Here's a multi-radar image from GRLevel3...this is evidently the most powerful storm in the country right now (with 74 dBZ). At the time that I snapped the picture below the storm was a few miles south of Waynesville, Missouri and is expected to pass not far to the south.

Upper left = Base Reflectivity
Upper right = Base Velocity
Lower left = Vertically Integrated Liquid (VIL) with the highest concentration being represented by the white colors (65 kg/m2)
Lower right = Echo tops (highest cloud tops are reaching about 45,000 feet into the atmosphere, represented by oranges)

Member Since: July 30, 2007 Posts: 76 Comments: 4063
291. Ivansrvivr
11:38 PM GMT on March 27, 2008
As Stevebloom pointed out it is Vulcanism that is the true culprit....those pointy eared Vulcans are up to no good again...

Seriously, with 2yrs of less than usual hurricane activity it the part of the Atlantic closest to home, I'm more inclined to think the 2 year break in tropical activity the U.S. has had is almost over. While I don't know much about the QBO and it's related effects, I know that the current La Nina cycle is loosening it's grip over the Pacific. That is an ominous sign in itself especially for the Eastern Seaboard. 2 years without the upwelling of large strong tropical activity close to the CONUS would seem to increase chances of activity by itself. Let's hope that steering currents push the bad ones out to sea while allowing some activity into the southeast U.S. to alleviate widespread drought conditions. It is walking a fine line between beneficial rains and widespread damage though.
290. TerraNova
11:32 PM GMT on March 27, 2008
Multiple tornado warnings in Missouri and Oklahoma.
Member Since: July 30, 2007 Posts: 76 Comments: 4063
289. SteveBloom
11:24 PM GMT on March 27, 2008
Re #278: "Like some have mentioned in previous comments, Antarctica remains very seismically active and any seismic activity could cause an event like this to occur."

Science, you see, is evidence-based, and there isn't any for the above conclusion. Vulcanism on the needed scale would be rather obvious, and it just isn't apparent.

An under-ice volcano may be contributing to the rapid acceleration of a couple of the West Antarctic Ice Sheet ice streams, but if so it's doing so by melting a little water (which then lubricates the sliding of the ice streams) rather than any sort of bulk melting. Note that this volcano was found because when it actually erupted a couple thousand years ago the first thing it did was burn right through the ice to the surface (at which point most of the heat went into the atmosphere anyway).

An undersea volcano breaking up an ice shelf is a bit more plausible, but there would be obvious signs of such activity in the relatively shallow water under and adjacent to the ice shelves, to say nothing of the string of them that would have been necessary to break up the series of ice shelves that have gone over the last twenty years.
288. Smyrick145
11:22 PM GMT on March 27, 2008
Nash
What are your thoughts on the upcoming hurricane season?
Member Since: September 30, 2006 Posts: 0 Comments: 14
287. Patrap
11:22 PM GMT on March 27, 2008
AL Gore NOAA Weather Radio PSA Link
Member Since: July 3, 2005 Posts: 421 Comments: 127636
286. extreme236
11:17 PM GMT on March 27, 2008
I think by now most people probably know Al Gore didnt event the internet...he was involved in the effort for public usage of it in Congress as Fmr. Speaker Newt Gingrich said:

"In all fairness, it’s something Gore had worked on a long time. Gore is not the Father of the Internet, but in all fairness, Gore is the person who, in the Congress, most systematically worked to make sure that we got to an Internet, and the truth is—and I worked with him starting in 1978 when I got [to Congress], we were both part of a 'futures group'—the fact is, in the Clinton administration, the world we had talked about in the ’80s began to actually happen."
Member Since: August 2, 2007 Posts: 19 Comments: 19234
285. Patrap
11:08 PM GMT on March 27, 2008
LSU ESL site Link
Member Since: July 3, 2005 Posts: 421 Comments: 127636
284. SteveBloom
11:07 PM GMT on March 27, 2008
Re #277: The link I provided explains exactly what Gore meant by that, and provides various quotes from various people (including those who might be called the "inventers" of the Internet as well as, interestingly, Newt Gingrich). The upshot is that "the Internet" referred to the large-scale network that came into being during the 1990s, the creation of which was the object of Gore's legislation.

But you didn't say who originated the slur. No name, no extra credit.
282. nash28
11:00 PM GMT on March 27, 2008
Don't get me started on Al Gore. Yeah, he may have made congressional pushes to get the internet into public use, but he had nothing to do with the binary behind it. For YEARS people actually believed he was the brainpower behind the computing science of it.

Uh, no....
Member Since: July 11, 2005 Posts: 190 Comments: 16972
281. Patrap
10:56 PM GMT on March 27, 2008
Looks like I'll be getting a raise then.
Offshore Pays.Link

Member Since: July 3, 2005 Posts: 421 Comments: 127636

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.