Topic: Large Crack in Antarctic Ice

[Downlinerz2]

    Blog article from AMS about 18-mile crack in Antarctic ice.

NASA Mission Monitors Birth of Antarctic Iceberg
November 3, 2011 · 0 comments

Resuming a multi-year mission to map Antarctic ice in mid October, NASA researchers discovered a miles-long crack in a major glacier that marks the beginning of a new mammoth iceberg. Operation IceBridge scientists flying in a specially instrumented DC-8 jet returned soon after to make the first-ever detailed airborne measurements of giant iceberg calving in progress.

The crack in Pine Island Glacier, which extends at least 18 miles (29 km) and is 165 feet (50 meters) deep—enough to swallow up the Statue of Liberty— could break free a chunk of ice more than 340 square miles (880 square km) in size from the vulnerable West Antarctic Ice Sheet.

 
This major rift cuts 18 miles (29 km) across in the Pine Island Glacier in western Antarctica. (Credit: NASA)

Pine Island Glacier’s ice shelf mostly floats, extending its unstable arm as many as 30 miles (48 km) away from the Antarctic landmass that grounds it some 500 meters (1,640 feet) below the surface. As the glacial ice inland flows slowly toward the sea and feeds the shelf, the arm eventually breaks, calving huge icebergs.

Pine Island Glacier last calved a significant iceberg in 2001, and some scientists have speculated recently that it was primed to calve again. But until an Oct. 14 IceBridge flight of NASA’s DC-8, no one had seen any evidence of the ice shelf beginning to break apart. Since then, a closer look back at satellite imagery seems to reveal the first signs of the crack beginning to cut across the ice shelf in early October.

“It’s part of a natural process, but it’s pretty exciting to be here and actually observe it while it happens,” says Operation IceBridge project scientist Michael Studinger of NASA’s Goddard Space Flight Center.

 
A close-up view of the crack spreading across the Pine Island Glacier ice shelf reveals the boulder-like blocks of ice that fell into the rift when it split. For most of its 18 miles (29 km), the crack was determined to be about 240 feet (72 meters) wide. The deepest points ranged from 165-190 feet (50-60 meters). (Credit: NASA)

The IceBridge team thinks that once the iceberg breaks free, it will leave behind the shortest extending arm of the Pine Island Glacier since recordkeeping began in the 1940s.

Pine Island Glacier is of particular interest to scientists because it is big and unstable, which makes it one of the largest sources of uncertainty in global sea level-rise projections. A collapse of the entire West Antarctic Ice Sheet (WAIS) is one of the nightmare scenarios climate forecasters envision in a warming world. If the WAIS were to melt, it could raise sea levels worldwide 20 feet.

NASA’s Operation IceBridge, the largest airborne survey of Earth’s polar ice ever flown, is in the midst of its third field campaign from Punta Arenas, Chile. The six-year mission will yield an unprecedented three-dimensional view of Antarctic ice sheets, ice shelves, and sea ice.

[Weather Display]

re sea level rises, I can say that coast errosion is accelerating here on this coat line..but that could be due to any number of factors
It is accepted that sea levels are rising slowly (like by cm's compared to what they were like) ..(often hard to calculate...i.e maybe the monitoring station has sunk instead!)...that does not sound like much but could be a tipping point for areas prone to coastal erosion during storms

[Farmtalk]

Can you imagine a 200 foot wide crack 18 miles long!? That is huge! Although I just dont see melting ice causing a ton of water rise elevation like Al Gore makes it out to be..

[SlowModem]

Can you imagine a 200 foot wide crack 18 miles long!? That is huge!

That's a big plumber!!!

[Farmtalk]

Can you imagine a 200 foot wide crack 18 miles long!? That is huge!

That's a big plumber!!!

 

[paleoguy]

Great story.  A twenty foot rise in sea level would pretty much wipe most of FL off the map...can they subtract senators and congressmen?

[WeatherHost]

^ Not to mention parts of California and Texas

[Old Tele man]

...maybe Lake Cahuilla will "rise" again from the Salton Sink in Imperial Valley, California?

[Farmtalk]

I simply just cant see the ocean levels displacing that much because of the ice melting....Think about it...20 ft!? I know that there are miles of ice beneath the water, but the density of water in liquid state is far more than ice.

[SlowModem]

I simply just cant see the ocean levels displacing that much because of the ice melting....Think about it...20 ft!? I know that there are miles of ice beneath the water, but the density of water in liquid state is far more than ice.

If you look at the water level in a glass of ice water, and then look at the level when the ice is melted, the level doesn't change.   

[Weather Display]

Do note that the sea level was much lower during the last ice ages (by much more than 20ft (think 100s of feet))
and then when the ice melted , the sea level rose again (alot of it on land ...its the melting of that which causes the sea level to rise)...
so if a bit more ice melts, especialy on land (like greenland, antartica itself), then the sea level was rise a bit more, like it has already done

[SlowModem]

Do note that the sea level was much lower during the last ice ages (by much more than 20ft (think 100s of feet))
and then when the ice melted , the sea level rose again (alot of it on land ...its the melting of that which causes the sea level to rise)...
so if a bit more ice melts, especialy on land (like greenland, antartica itself), then the sea level was rise a bit more, like it has already done

There are some that think that the Garden of Eden is under the Persian Gulf, hidden by the melting of the ice and the filling of the gulf.

[Downlinerz2]

    I don't think a glass of water is enough water to resolve the difference. It is kind of like weighing a feather on a bathroom scale.  But, even with the difference in density, the difference is not all that huge.  Ice in a glass floats, but it is not riding really high in the water, it is mostly submerged.

[DanS]

This topic reminds me of the movie "The Day After Tomorrow".

[Weather Display]

yes, but its ice on land....if that melts...that ice is not displacing any water

[Farmtalk]

They say 80% or so of ice is underwater, if ice occupies a larger space than water, even though water is more dense, would that not cause much difference in change at all?

[4wd]

There's no reason for this story to have any sort of climate change nonsense tacked on it.
The glacier continually creeps into the ocean and this can't go on indefinitely as it becomes increasingly affected by tides and currents.
It has a known history of losing large chunks approximately every ten years and this time is much on schedule.
Antarctic ice has not been decreasing - why should it, away from the very coast the air temperatures never get anywhere near above freezing pont even in the height of 'summer'.

[Weather Display]

but its not the air temperature that is melting the sea ice
but the warmer sea temperature around and under it

[4wd]

It isn't particularly being melted, just breaking off which as above is what happens to glaciers every few years.
This incident is entirely un-related to anything to do with climate change or warming.
A large section breaking off could be considered an indication that it isn't melting on hitting warm(er) water if anything - because it has grown to an eventually un-sustainable length.

[Weather Display]

and when it breaks off, it can then drift into warmer sea areas and then melt/break up even more
once you loose sea ice, it lets the ice on the land slide off ...i.e the sea ice holds that back
(slow process)
note that there is not alot of snow falling to replace any ice lost, in the polar regions .

[4wd]

That's the alarmist version of a normal process.
A large section breaks off roughly every ten years, there's no reason to suppose a normal calving process will induce a sudden slide into the sea - since it never did before.
Unless you want to try to pointlessly scare people with exagerrated imaginary scenarios obviously. 

[Weather Display]

I never said sudden
I said slow process

I am not trying to be alarmist either

just pointing some observations out, thats all

[Downlinerz2]

   Article about new study that is supposed to account for what has caused the increase in sea levels.  They say oceanic thermal expansion =40% and glacier melting=35%.  Article here:
    
    http://www.smh.com.au/environment/climate-change/scientists-account-for-sea-level-rise-20111104-1mzox.html

   And another article that reports studies that say the storminess the last year prevented it from being a record setting year of arctic melting.    
  
http://news.yahoo.com/storms-may-prevented-record-loss-arctic-ice-212208543.html

[Weather Display]

yes, the thermal expansion of water does look to be a a big player in sea level rise (and fall during colder periods)
when you think about it, the oceans are really not all that deep compared to the size of the planet
i.e think along the lines more like a relatively thin layer of water spread across the surface...expand that thin layer, and it will spread across the (relatively flat compared to size ) surface even more (ie as the volume increases)

[WeatherHost]

I'm sure there are other cosmic elements similar to the lunar effect on tides that haven't been studied either.  Maybe some that we're not even aware of yet.