Wilkins Ice Shelf breaking

[biffvernon]

Yes Grey Wolfy, those pictures are fantastic. Maybe they show the biggest, quickest event on the planet's surface since satellite imagery began? When I first looked I wondered if the 28 to 29th February colour change was some artefact but it becomes clear when you go to the high res pics. If you haven't yet, folks, do click around the high resolution links.

Edited March 29, 2008 by biffvernon

[SnowBear]

How big did they say the area was in the break up???

[Filski]

Without wanting to cloud the issue but I suspect the straw that broke the camels back comprises 2 parts.

1. Cross section of the polar vortex. I have been looking into the polar votex and AAO for a little while to see if there is a predictive element for the aussie snow season. A weaker vortex (shown by negative values or the red patch) will influence the SLP and ultimately the sea level in that area. Differences of only a little would be enough to cause stress in the ice shelf.

2. I've read reports of severe storms and wave heights of several tens of metres in the southern ocean around that period. I can't be stuffed looking for the relevant charts but I'm willing to bet that this at least in part was caused by wave action from storm activity and worsened by a weakened structure due to melting broguht about by GW.

I am not in anyway suggesting that this is or is not a GW related event. It is a very complex issue and it is worth following up every avenue. The storms are 'weather' but the AAO is certainly climate.

[Gray-Wolf]

The strengthening of the circumpolar winds (ascribed to G.W.) lead to greater swell sizes and more impact on the fringing shelves. In 2002 part of iceberg B19 (from Ross) was smashed by a Storm swell generated 1/2 a planet away in the Bearing sea so the link between shelf/berg disruption and sea swells are well documented.

If we see stronger storms as a result of more energy trapped in the system [warmth] then we will see more of the fringing shelves/glacial snouts fall foul of them.

Sea level rises [however 'pifflingly small'] float the shelves higher putting immense strains on it's connection with the land, this coupled with the 'waggling' produced by stronger swells leads to only one thing.

Once the 'girdle' of ice collapses then all the ice being held back by it spills out. This ice raises sea levels exacerbating the problem further.

Edited March 30, 2008 by Gray-Wolf

[Gray-Wolf]

The ice remnants seem to have been well mushed over the past 3 weeks. The above image is Wilkins from yesterday (2pm).

[Gray-Wolf]

though blighted by cloud at the bottom you can see how much 1 day can do to melting ice by studying above the island to which the rest of Wilkins 'hangs by a thread'.

if you look at the sst anom there you can start to see why!

[SnowBear]

GW, I dont think those two pics are to the same scale, the second pic seems compressed laterally, or the first stretched, seems they are at differing angles as well, all which gives the illusion of ice loss on the peninsula on the left. If it was true then we would be looking at a bigger loss of ice than the collapse of 25miles by 1.5miles approx a little while ago. Seems to be a different altitude too.

Be interesting to see what angles to the area the pics were taken, approaching or leaving the area etc.

Edited April 1, 2008 by SnowBear

[Gray-Wolf]

GW, I dont think those two pics are to the same scale, the second pic seems compressed laterally, or the first stretched, seems they are at differing angles as well, all which gives the illusion of ice loss on the peninsula on the left. If it was true then we would be looking at a bigger loss of ice than the collapse of 25miles by 1.5miles approx a little while ago. Seems to be a different altitude too.

Be interesting to see what angles to the area the pics were taken, approaching or leaving the area etc.

Same scale (250m resolution) but brother and sister sats .Piccie one was from Terra at 14:30 GMT and the second from Aqua at 19:30GMT (a day apart).

The 'weather' that caused the 'no show' on the early pm shot yesterday must also be responsible for the drift the ice did (above the 'thread' connecting the remnant sheet to the island). Hopefully todays images will reveal the major ice remnants (below the 'thread') at the same time of day.

No jiggery pokery intended but the shadows from the mountains should wise you up to the differing times of day

It would save me a lot of time and effort to post links to the individual frames from the MODIS sat images (or even just time/sat)and not have to resort to croping each one to a size a calculator would cope with but Atlantic F. claims that they cause his PC to fall over as full 250m resolution images and I wish for all of the viewers/readers to share.

That said I do try and post times and sats so you can always revert to source if you feel like it.

Ian.

Edited April 1, 2008 by Gray-Wolf

[Gray-Wolf]

http://www.natice.noaa.gov/press_release/index.htm

Nearly mid-winter down under and still we are recieving reports from Wilkins.

[BLAST FROM THE PAST]

What is fascinating is the continued growth of ice down there even withstanding the ice shelf collapses. That for me makes the record last year and the fact we are ahead now of even last year even more remarkable....the collapse is steadying a potential sea ice extent runaway.

here

here

here

ta to cryosphere.

BFTP

Edited June 11, 2008 by BLAST FROM THE PAST

[Gray-Wolf]

Without going over the rational for recent increases in ice extent in Antarctica it becomes quite apparent that the areas where ice growth is occurring

are related to the position of the peninsula with no such 'growth' being situated directly across the continent from it. The phenomena itself is driven by the same thing that has cost us/is costing us the Ice shelves on the peninsula and causing both the increased snowfall there and the rapid shrinkage of its glaciers.

I draw no encouragement from witnessing the phenomena as ,to me at least, it helps highlight the 'forcing' of the climatic responses to global warming being felt down there.

Swan song? I believe it is.

Edited June 23, 2008 by Gray-Wolf

[Chris Knight]

Without going over the rational for recent increases in ice extent in Antarctica it becomes quite apparent that the areas where ice growth is occurring

are related to the position of the peninsula with no such 'growth' being situated directly across the continent from it. The phenomena itself is driven by the same thing that has cost us/is costing us the Ice shelves on the peninsula and causing both the increased snowfall there and the rapid shrinkage of its glaciers.

I draw no encouragement from witnessing the phenomena as ,to me at least, it helps highlight the 'forcing' of the climatic responses to global warming being felt down there.

Swan song? I believe it is.

Isn't it just geography GW, that dictates where the ice forms? If you look at a map like this:

The tip of the peninsula, and bits of the continental coast on the opposite side are outside the Antarctic circle, thus still getting some daylight, even in the midst of the southern winter.

Talking of which, it would seem that a polar high at the south pole is a very different affair than one at the north. I for one would not like to be out there!

Edited June 23, 2008 by Chris Knight

[Gray-Wolf]

Isn't it just geography GW, that dictates where the ice forms? If you look at a map like this:

The tip of the peninsula, and bits of the continental coast on the opposite side are outside the Antarctic circle, thus still getting some daylight, even in the midst of the southern winter.

Talking of which, it would seem that a polar high at the south pole is a very different affair than one at the north. I for one would not like to be out there!

Correct !

The circumpolar winds end up forming a 'closed system' down there with only the tip of the peninsula beyond it. It is the way that the wind has increased (put down to global warming) that leads to cold bottom waters being overturned (with a little help from the Coriolis affect) as the wind drives the circumpolar current. Of course the peninsula disrupts this flow as it butts into it but also the Mcmurdo end of Ross juts out in a similar way (but nowhere near as far) and it is in the lea of these obstructions we see the greatest 'ice gains'.

Am I drivelling or can you catch the flavour of what I'm saying?

Edited June 23, 2008 by Gray-Wolf

[Gray-Wolf]

I just thought I'd better add on this sea bed map to highlight just how far the Peninsula does stick out into the southern ocean disrupting things!, I'm sure you're already aware of this but other readers may not be