Winter break up of Wilkins ice shelf

[Gray-Wolf]

http://www.theage.com.au/environment/scien...80711-3dsy.html

I suppose it had to happen and I suppose it'll be big news (like the mid winter collapse of the Argentinian ice dam) as it makes a good 'visual' story.

My point is this, the scientists tell us that the base of Wilkins is being eroded by warm waters (remember it's at it's coldest down there right now) leading to this 'unexpected collapse.

We are told that the increase in the circumpolar wind has led to ,via a little help from the Coriolis affect, the subduction of the warmer southern ocean waters and the upwelling of 'cold' bottom waters. Obviously there comes a point where there are no 'cold bottom waters' left to up well and warmer, southern ocean waters, will replace it.

When this starts to occur we can expect the rapid disintegration of all of Antarctica's ice shelfs by the erosion of this warmer waters. We all know what comes next.

Is Wilkins a start of this process as the warmer waters penetrate deeper into the coastal Antarctic waters (and not just the 'sticky out' peninsula) or is this just another 'norm' for down there?

[bluecon]

The 'Sky is Falling' and raising taxes is the only solution.

[Gray-Wolf]

The 'Sky is Falling' and raising taxes is the only solution.

?

What will increasing tax burdons do to reduce the consequences of rapid climate change???

Govt.s are only 'bandwaggoning' AGW as the public a rightly alarmed by it all and the politico's see vote preservation in appearing 'greener than thou'.

I mean look at the UK Govt. who want to ban 'free' plastic shopping bags but carry on regardless with their bypasses, motorway widening, airport extensions plans.

Politics is full of 'political types' ......the last kind of personality type you'd ever want in charge.

[Gray-Wolf]

Antarctic ice shelf collapse 'imminent'

By Geoffrey Lean, Environment Editor

Sunday, 13 July 2008

Scientists are warning that an Antarctic ice shelf the size of Northern Ireland is on the verge of disintegration, even though it is now the middle of the southern hemisphere's winter.

The European Space Agency says new satellite pictures show that the Wilkins shelf – the largest to be threatened so far – is "hanging by its last thread". Extending for approximately 5,600 square miles, it has been held in place by a thin ice bridge connecting it to an island, but this is now fracturing.

The shelf, which lies near the base of the Antarctic Peninsula, had not been expected to collapse until the early 2020s. It provides further evidence that the planet is warming more quickly than predicted.

Scientists are stunned that it is continuing to melt in the depths of winter, and believe that warm water is welling up from the ocean to attack it from underneath. So far seven shelves on the peninsula have collapsed due to climate change.

On Friday, President Bush – who last week told the G8 summit "Goodbye from the world's greatest polluter" – defied a 2007 ruling by the US Supreme Court to take action on global warming under the Clean Air Act.

---------------------------------------------------------------------------------------------------------

Todays 'Indi' seems to think that a Northern Ireland sized piece of collapse is news

[laserguy]

The shelf, which lies near the base of the Antarctic Peninsula, had not been expected to collapse until the early 2020s. It provides further evidence that the planet is warming more quickly than predicted.

Scientists are stunned that it is continuing to melt in the depths of winter, and believe that warm water is welling up from the ocean to attack it from underneath. So far seven shelves on the peninsula have collapsed due to climate change.

According to this, our (?) CO2 is pulling air temps down but you're saying it's warming an area in the depths of the Antarctic ocean and causing (relatively) ice-cube sized lumps to break off. Okaaayy.....

http://icecap.us/images/uploads/Since_2002.jpg

Why can't they just accept that their original prediction of a 2020 collapse was simply wrong,instead of falling back on that old standby climate change when they get caught out? And what's the big deal with ice shelves collapsing anyway? Haven't they always done just that,and why would they want to convince a gullible -or rather a disinterested and consequently malleable public -that something unusual is afoot? If ice shelves kept on growing and never broke off/melted,they'd extend to the North Pole by now! Has it not occured to their 'let's identify a non-existant problem minds and find something else to hang onto CO2's coat tails' that any unusual melting of shelves might,just might be attributable to the increasing cold and consequent ice build up in Antarctica's interior forcing the ice further into warmer waters?

[Shiny_Bottom_1]

Is Wilkins a start of this process as the warmer waters penetrate deeper into the coastal Antarctic waters (and not just the 'sticky out' peninsula) or is this just another 'norm' for down there?

I dont know about answering the first part GW (its more or a predictive rather than factual answer), but the later part (regarding is this the norm) I thinks the key question.

Unfortunately I cant answer that, but would be good to see any reports of this before?

[Iceberg]

Well its been stable for the last century, it's lost 1350 km² with a rough estimate of 500 to 700 km² in addition being lost if the bridge to Charcot Island collapses.

It looks as if something different is happening to this shelf over Larsen B.

[Gray-Wolf]

Hi Iceberg!

The fact that the shelf is collapsing in large bergy chunks would hint at another process to 'the norm' occurring on Wilkins.

If you imagine the whole shelf undergoing basal thinning then, if you add in the winter storm swells, you can see why this type of breakup is occurring and we are not seeing the more 'normal' type of collapse where chunks/strips fall off at the leading edge along lines of weakness in the ice (old crevasses etc).

The fact that Wilkins is quite away from the finger of the peninsula shows us that the warming there is different in nature to that on the peninsula proper. This area is well within the protective girdle of the circumpolar winds/current and not stuck through it (as with the peninsula proper) so any 'warming' turning up here would suggest that the 'warmth' is now breaching the wind/current.

If ,over the next 2 years we see shelf collapses geographically removed from the peninsula I think we'd better start to worry!

[ghrud]

Well its been stable for the last century, it's lost 1350 km² with a rough estimate of 500 to 700 km² in addition being lost if the bridge to Charcot Island collapses.

It looks as if something different is happening to this shelf over Larsen B.

How can you state that this ice shelf has been stable for the last century; where are you getting your statistics from? We've only had satellite data since the late 70's.

Also, to a point GW raised earlier in this thread about the reporting of the Argentine Perito Moreno glacier Ice Dam. I've done a little reseach on this and according most of the Argentine tourist WEB sites the ice dam, breaks-up and rebuilds on a regular basis, didn't exist at the end of the 19th century as the glacier that forms it was some 700m futher back up the mountain. Which would suggest that this glacier is advancing not receeding. Note the word suggests, as I don't know if it is fact!

[Iceberg]

Ghrud, that was a comment made by the BAS, ice samples and boat charts will support this. Before this time nobody explored it so it's very difficult to say.

A partly agree GW, I happy to keep an open mind on this though. As you say this is a cause for concern probably an Amber, when ice shelfes collapse away from the peninsula, WAIS, ROSS etc then it switches to Red.

[Gray-Wolf]

A partly agree GW, I happy to keep an open mind on this though. As you say this is a cause for concern probably an Amber, when ice shelfes collapse away from the peninsula, WAIS, ROSS etc then it switches to Red.

Agreed

[Gray-Wolf]

According to this, our (?) CO2 is pulling air temps down but you're saying it's warming an area in the depths of the Antarctic ocean and causing (relatively) ice-cube sized lumps to break off. Okaaayy.....

I wasn't going to rise to it Laser but what the hey!!!

If that 'ice cube' was jamming some ice blocks in place and they ,in their turn, were holding in place some house sized ice blocks which, in their turn, were holding back N.I. sized sheets of ice which , in their turn, were holding back a continent of ice 3 miles thick from slipping into the sea then I'd be worried to see the 'ice cube' fail.

One heck of a card house but the cards are starting to fail.

One heck of a domino chain but the first dom' is toppling.

[ghrud]

I wasn't going to rise to it Laser but what the hey!!!

If that 'ice cube' was jamming some ice blocks in place and they ,in their turn, were holding in place some house sized ice blocks which, in their turn, were holding back N.I. sized sheets of ice which , in their turn, were holding back a continent of ice 3 miles thick from slipping into the sea then I'd be worried to see the 'ice cube' fail.

One heck of a card house but the cards are starting to fail.

One heck of a domino chain but the first dom' is toppling.

Can you point me in the direction of some science that can substantiate your theory of this domino effect?

[BLAST FROM THE PAST]

So the Gakkel Ridge pumping out lava at 1000 degrees at heights of 2km are not affecting the arctic ocean temps or ice in any way even thought the active ridge is bigger than the Himalayas but a global rise of 0.7c air temp has warmed the deep lower oceans to such an extent that the ice shelves are collapsing. See how ridiculous that sounds...and actually is.

BFTP

[Gray-Wolf]

So the Gakkel Ridge pumping out lava at 1000 degrees at heights of 2km are not affecting the arctic ocean temps or ice in any way even thought the active ridge is bigger than the Himalayas but a global rise of 0.7c air temp has warmed the deep lower oceans to such an extent that the ice shelves are collapsing. See how ridiculous that sounds...and actually is.

BFTP

Wow, are you saying there is a brand new spreading centre opening up down there with a brand new set of drivers that haven't been in opperation for millenia?

I wonder how I missed that!

Course you'd need something of the scale of the late Terrtiary volcanics to cause the changes you outline and by then the amount of CO2 pumped into the air would've caused the same scale of warming as when the Deccan traps were being flooded....to a depth of over a mile...

Can you point me in the direction of some science that can substantiate your theory of this domino effect?

I think if you look back over the past 15yrs of melt on the peninsula you'll see just how this works

[BLAST FROM THE PAST]

Wow, are you saying there is a brand new spreading centre opening up down there with a brand new set of drivers that haven't been in opperation for millenia?

I wonder how I missed that!

Course you'd need something of the scale of the late Terrtiary volcanics to cause the changes you outline and by then the amount of CO2 pumped into the air would've caused the same scale of warming as when the Deccan traps were being flooded....to a depth of over a mile...

Please tell everyone GW how 0.7c warming has reached 1000s of feet below the ocean and is big enough to collapse an ice shelf. You know the more one reads that the more outlandish it becomes...it just doesn't ring true.

BFTP

[Gray-Wolf]

Please tell everyone GW how 0.7c warming has reached 1000s of feet below the ocean and is big enough to collapse an ice shelf. You know the more one reads that the more outlandish it becomes...it just doesn't ring true.

BFTP

Have you ever hear of the north Atlantic drift? do you know the temp differences within and outside the current Do you know that it has a major influence on the NW European climate? Oh, you did.

The increase in winds strength, as measured over the past 30yrs, of the circumpolar wind has led to an increase in speed of the circumpolar current. Temp measurements have found that ,inside the current, cold water upwelling is occurring. What is driving this water off the bottoms? Warm water!. The warm water is subducted down as a result of the interaction of circumpolar wind on circumpolar current and a bit of spin from our old friend Coriolis.

The data is there, the cold water 'upwelling' is a fact and so ,it follows, the warm water 'subduction' must occur (nature like balence.....certainly doesn't like great holes in the ocean behind where cold water is being 'pushed up'.

you can safely say ( due to waters quirky temp/density thing at 4 c) that the waters above are warmer than the waters below which are seasonally flooded with cold meltwater outflow from the continent. The question must be 'how much cold water was there down there to be flushed up?' and 'how long before this new ,dynamic, overturning of the ocean is all out of 'cold' and starts to bring up slightly warmer waters?' and then warmer waters still, until nature has re-established some kind of balance and the inner Antarctic ocean is a similar temp to the southern ocean?

[jethro]

But that would rely upon no heat loss, only heat gained and kept. No climate system on Earth works like that, never has done, never will do. If heat transferred to oceans was retained along those lines, we've had boiled away out of existence a long time ago.

When it was suggested that volcanoes were heating bottom waters and these were up-welling, contributing to ice melt, it was categorically dismissed as impossible; so how come bottom up-welling works when it's because of AGW but if nature has a hand, then it's impossible?

Genuine question BTW.

[BLAST FROM THE PAST]

But that would rely upon no heat loss, only heat gained and kept. No climate system on Earth works like that, never has done, never will do. If heat transferred to oceans was retained along those lines, we've had boiled away out of existence a long time ago.

When it was suggested that volcanoes were heating bottom waters and these were up-welling, contributing to ice melt, it was categorically dismissed as impossible; so how come bottom up-welling works when it's because of AGW but if nature has a hand, then it's impossible?

Genuine question BTW.

Exactly Jethro, it is what I'm getting at but you have put it perfectly.

BFTP

[Gray-Wolf]

But that would rely upon no heat loss, only heat gained and kept. No climate system on Earth works like that, never has done, never will do. If heat transferred to oceans was retained along those lines, we've had boiled away out of existence a long time ago.

When it was suggested that volcanoes were heating bottom waters and these were up-welling, contributing to ice melt, it was categorically dismissed as impossible; so how come bottom up-welling works when it's because of AGW but if nature has a hand, then it's impossible?

Genuine question BTW.

Jethro, are we not debating, over a wide area, the 'facts' of 'Global Warming'? The term would imply that the planet is capable of amassing heat when circumstances permit (high CO2 levels) as past 'warmings' show us. In so far as the oceans 'boiling away' we yet have that to come (in about 4.5 billion years)

Again I must plead with you to check your scales when you raise the issue of volcanic warming of the oceans. Our planet, compared to our spreading centres, is huge. The amount of water contained is the worlds oceans is huge. The only time I've seen interaction between lava's and ocean is where pillow lava's are erupting below sea level or lava flows are pouring into the sea. The fact that divers are down there filming the pillow lava's would seem to suggest that the insulation provided by the water is sufficient to allow close observation. Though I will not discount an 'impact' on local sea temps this is an incredibly small part of the warming observed in the first 1,000ft of ocean.

The fact that this oceanic warming is occurring must give some idea as to the immense amount of heat the planet has retained/absorbed over this warming period and this 'extra' heat will flow throughout the ocean basins making it up to the north pole and down to the south pole.

The fact that the Antarctic continent sits over the geographic south pole and is a very tall land mass has led to the development of the circumpolar winds and the Katabatic outflow off the continent. Both of these effects have tended to stall the warmer waters making it to the Antarctic coasts (apart from the peninsula which sticks out beyond and allows the warmer waters to follow the coast in beyond the circumpolar winds) and leading to the regimented collapse of the ice shelves in that area......this penetration is now as far as Wilkins (it would appear).

Nature loves balance and ,in time, the splendid isolation that Antarctica exists in will be breached and rapid changes will ensue there.

[Gray-Wolf]

From Nat. Geo.

July 14, 2008—Another collapse of the Antarctic Peninsula's Wilkins Ice Shelf has the mass of floating ice hanging by a thread, as seen in the above satellite images.

Between May 30 and July 9, the European Space Agency's Envisat satellite captured the latest in a series of large-scale Wilkins breakups. The most recent collapse, which caused a loss of some 520 square miles (1,350 square kilometers) of ice, puzzled scientists: It is the first-known collapse to occur in the Southern Hemisphere winter.

The shelf is now stabilized by a thin ice bridge (seen in the center of the images) that anchors it to nearby Charcot Island.

But this link may soon be severed by a new fracture, first seen in a July 8, 2008, image (above).

Scientists fear that if the bridge falls the entire shelf could disintegrate in relatively short order. They also believe warming oceans are rapidly thinning the shelf from underneath.

"Over the past two decades or so we've seen the most pronounced climate change in the Arctic, and the Antarctic has always been viewed as this sleeping giant," said Mark Serreze, a senior scientist at the National Snow and Ice Data Center in Boulder, Colorado.

"What's happening in terms of the Wilkins Ice Shelf is evidence that change is really happening there—and this sleeping giant is starting to stir." —Brian Handwerk

Seems that NSIDC are 12 years behind B.A.S. as they told us the 'sleeping giant' was stirring 12 years ago........and a lot has happened in 12 years.

[Mondy]

http://www.theage.com.au/environment/scien...80711-3dsy.html

I suppose it had to happen and I suppose it'll be big news (like the mid winter collapse of the Argentinian ice dam) as it makes a good 'visual' story.

My point is this, the scientists tell us that the base of Wilkins is being eroded by warm waters (remember it's at it's coldest down there right now) leading to this 'unexpected collapse.

We are told that the increase in the circumpolar wind has led to ,via a little help from the Coriolis affect, the subduction of the warmer southern ocean waters and the upwelling of 'cold' bottom waters. Obviously there comes a point where there are no 'cold bottom waters' left to up well and warmer, southern ocean waters, will replace it.

When this starts to occur we can expect the rapid disintegration of all of Antarctica's ice shelfs by the erosion of this warmer waters. We all know what comes next.

Is Wilkins a start of this process as the warmer waters penetrate deeper into the coastal Antarctic waters (and not just the 'sticky out' peninsula) or is this just another 'norm' for down there?

May I ask why this is of such concern?

Are you forgetting that most of Antartica is getting cooler making most of the ice sheets increase?

Wilkins is in the body of water where temps will be naturally higher (map). It's also ideally placed to experience earth tremors due to volcanoes erupting underwater- do you agree this isolated breakup is conceivably linked to underwater shenanigans?

Also, have a read of this. Re-freeze is the word.

I honestly would hate to think this a deliberate attempt at AGW propaganda. Please correct me if I'm wrong about that.

[Gray-Wolf]

May I ask why this is of such concern?

Are you forgetting that most of Antarctica is getting cooler making most of the ice sheets increase?

Wilkins is in the body of water where temps will be naturally higher (map). It's also ideally placed to experience earth tremors due to volcanoes erupting underwater- do you agree this isolated breakup is conceivably linked to underwater shenanigans?

Also, have a read of this. Re-freeze is the word.

I honestly would hate to think this a deliberate attempt at AGW propaganda. Please correct me if I'm wrong about that.

Both the BAS team and the American crew at Mcmurdo are singing from the same hymn sheet on this one and I am purely bringing that information to the site.

No one can fully explain how this mid winter break up could occur but the all point out that the disintegration of the shelf is different than other shelf collapses with the shelf breaking into large floes instead of the normal frontal 'slivers' of collapse as the ice fails along the pre-existing internal fractures present in all glaciers/shelfs.

Our pals , the seals with their thermometer 'caps' have show that the waters below Wilkins, and across this area of the peninsula, are abnormally warm suggesting that the southern ocean has somehow now breached the circumpolar current. Where this so then we will see all of the 'floating shelfs' suffer the same fate as Wilkins over the coming few years.

I have nothing to 'gain' from my understanding of the processes at either pole. I am in the pay of nobody neither am I affiliated to any group or body in the field of AGW.

I am ,however, a father and so need the best view of our changing world to give the boys the best chance of not falling foul to any of the future 'climate shocks' we are set to endure.

In so far as Delta is concerned I envy him his optimism and world view.

[BLAST FROM THE PAST]

I find it all rather sinister really.

BFTP