Mechanical erosion of ice sheets

[Iceberg]

realclimate is unfortunately blocked from work :lol:

Rahmstorf's recent paper though confirms the findings (this is still a conservative assessment !), based on a linear rate of increase, without a temperature related proportional increase in icemelt, ross, WIAS collaspe etc.

http://www.pik-potsdam.de/~stefan/Publicat...cience_2007.pdf

[parmenides3]

You'll love this one: UNEP's latest: http://www.unep.org/Documents.Multilingual...D=5599&l=en

That's the press release. There are links to the main report on the home page; it's 98mb, so take care. I read the summary; nothing new here, in the sense that I've already come across most of it in the last 6 months; it's actually more of a synthesis report than new stuff. But worth a peek, nonetheless.

:)P

[Iceberg]

Thanks P3 I did give that a read.

http://www.geotimes.org/current/article.ht..._antarctic.html

The above is article that's recently come on to geotimes. It seems to be a bit of a re-hash from a few years ago.

But IMO the results are a little worrying.

[parmenides3]

This one is especially for G-W: http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_2.pdf

Hansen's latest on the possibility of a WAIS collapse.

Enjoy.

:)P

[Iceberg]

A very good report from Hansen Not read it all yet !. But he goes into climate forcings, the GHG temp lag etc, also brings together the latest findings about ice buttresses and unsea ledges.

[Iceberg]

Not sure GW is around atm....

But http://www.ifm.zmaw.de/~wwwrs/RS_RossSeaPolynyaMaps.html

Shows maps of curreny Polyna's in the Ross at McMurdo sound atm.

Looks quite large for the time of year, (not sure wether it's due to wind or warm sea upwelling.

[Gray-Wolf]

http://earthobservatory.nasa.gov/Newsroom/...7070325354.html

Family and garden and deluge have kept me away for a while and judging from the threads on this section that have grown since life dragged me off (kicking and screaming!) I see I haven't missed much

The above link is another disturbing side to the current effects of climate change in the high arctic. The prospect of 'bogs' draining as the permafrost melts leaving huge tracts of lignite and peat that can be 'lit with a lighter' worries me a tad (espec. if electrically charged events start to become more frequent visitors to the polar regions).

Ho Hum, B.A.U.

[jethro]

Found this GW, thought it may interest you:

http://www.sciencedaily.com/releases/2007/...70814160901.htm

[Gray-Wolf]

Thanks for thinking of the thread when you saw it jethro!

I had read it (my light breakfast read Science Daily) and think I linked it to another thread (either Corinthians or another on this page) but never thought to stick it in here!!!

As we all know the Ross embayment is mainly below sea level though solid with ice (an agglomeration of many glaciers).

If the 'leading seaward edge' started to lift ( by melt and sea swell) whilst the rear base of the embayment were being flooded with melt-water both from the sub-glacial lakes/streams or the water from NASA's 2005 revelations of the mountain melt occurring on the 'horse-shoe ' of mountains surrounding Ross then you start to approach the point where Ross fractures and floats free (to melt in the southern oceans. The story wouldn't end there though as the East Antarctic Ice Sheet is the main contributor to the embayment and so all of it's 'girdled glaciers' would be free to do the same as the West Antarctic Ice Sheets glaciers.

The mechanics of the disintegration and the metre's of sea level rise caused would be on a micro time scale (2 to 3 years?) which is why I'm so concerned/interested in the changes to the shelf that Antarctic summer shows us.

Soon be time to start watching again but presently Dean, and his yet to form pals, calls me.........

[Gray-Wolf]

I may be a little premature but have we started turning the corner down south already?

[parmenides3]

Too early; the max is a few weeks away there, too, afaik. If it turns out you were right, I give you permission to start panicking...

:)P

[Filski]

I don't know P3, the AAO is now trending positive. This is a sign of the change of season and a tightening of the polar vortex with highs now sitting further south. Perhaps a few more weeks yet but the change has certainly started.

[parmenides3]

I can't find anything with a quick search which helps us much, here, filski, so it's hard to know what's going on, or what is likely. Certainly, a shift in the AA from a +1M km2 anomaly to a zero anomaly in a week or two seems quite peculiar...

:)P

[Gray-Wolf]

Shows you what the strenthened circumpolar winds can do to the ice edges where storms push up a decent swell under the ice edge P3.

[parmenides3]

Hi, G-W. Heads-up for you and others; found an interesting, very short, non-technical, but factual, summary of the GIS and WAIS on the Lloyd's of London website. If you go to 'Lloyd's 360' section, you'll finds links to a series of articles relating to risk and the insurance industry, including the climate section.

In that article, there is a reasoned discussion why the insurance industry needs to plan for a changing climate, which recognises the uncertainties in climate science but also concludes that certain changes are at a sufficient level of risk as to demand resonse and preparation from their members.

Stephan Harrison's essay on the ice sheets is in the middle. It is up-to-date (including material from this year) and explanatory: The WAIS is a risk for certain reasons. It describes johulklaups ('ice dam' collapses) and also sub-glacial water flows. It explains the uncertainties and also the reasons why there are scientific concerns very clearly.

I'll find the link later, for the lazy.

:)P

[Iceberg]

Here's the link

http://www.lloyds.com/NR/rdonlyres/FCA144E...hangeReport.pdf

Are you connected with the Insurance industry then P3 ?. and Climate Change ?.

The institute of British Insurers issued something similar last year. They are definately taking it seriously which has to be good news.

Edited August 26, 2007 by Iceberg

[parmenides3]

Here's the link

http://www.lloyds.com/NR/rdonlyres/FCA144E...hangeReport.pdf

Are you connected with the Insurance industry then P3 ?. and Climate Change ?.

The institute of British Insurers issued something similar last year. They are definately taking it seriously which has to be good news.

Thanks, iceberg. 'No' and 'a bit', are the answers to your questions about me. It was just something I happened across.

Most corporations are taking it seriously, too. Some governments are taking it seriously. The number of industries which are keeping their distance is increasingly small. Most of the general public at least broadly see that it is an issue, though won't do anything about it. My worry is that it takes so long for amything meaningful to get done, by which time some choices will be redundant. Urgency is probably the key issue now.

:)P

[Iceberg]

Thanks for your reply's P3.

Certainly a career change if you want one, I think every large financial company will have a full time and very well paid CC advocate in 12 months time to digest news as it comes out and report how it effects them. OTT Sorry.

[Gray-Wolf]

Thanks for the link guys, seems like I wasn't being to 'extreme' to voice my concerns over the imminent,rapid de-icing of large areas of the southern continent .

[parmenides3]

Thanks for the link guys, seems like I wasn't being to 'extreme' to voice my concerns over the imminent,rapid de-icing of large areas of the southern continent .

Indeed; your concerns have a real-world presence, here. I'd be cautious about that 'imminent', though. As Harrison says, though there is a risk, it is unquantifiable, due to insufficient information. Timing and likelihood being impossible to estimate accurately, it is left down to us, or scientists, to weigh the evidence that is available and have a feeling about what seems likely. Hence our differences: you have done this and feel a 'collapse' is likely fairly soon. I have done it and feel that a 'collapse' is more likely some years from now (don't ask me how many!)

I was impressed by the clarity and simplicity of the writing in the document as a whole; no unnecessary detail, no wild speculation, but sound reasoning and solid, scientific explanation. I wish I could do that...

:)P

[Gray-Wolf]

Been 'uh ming' and 'ah hing' about the polar melt and rather than clog up 'Corinth's' thread I'll post them here.

Is the only thing that stands between a small, central, eroding chunk of Multiyear ice at the North Pole (slowly/quickly melting back year on year) the surrounding topography and the micro-climate that it ensues exists there?

To me it would seem natural that areas to the north of any 'taller' topographic areas of the polar regions, especially those with a good distance of 'shallow water/shelf sea attached to the north of them, would retain/protect it's 'multiyear ice/sea bed connection' better than those flanked with 'gentle sloping' coastal regions lacking in both;

Deep shadow,

Upland areas close to the coastline,

and this , I think is what we can see of the remnants of the sea ice this year attached only to the rear of the Greenland uplands and the ragged coast of NE Canada.

It either takes a while for the coastal 'strip' to melt back and 'free' the more central multiyear ice or there will be mechanical failure/shearing in the more central area of the multiyear 'pack ice', and the final breakaway of this 'rotating' central core area of multiyear ice at the call of both wind and wind and currents?

Edited August 28, 2007 by Gray-Wolf

[Gray-Wolf]

The more I view that movie (from Cryosphere today) the more I see that the 'fracture' of that area of 'multiyear ice' did occur this year and resulted in a west wards drift of the 'sheet' towards the Svalbard region. Because of the synoptic setup recently,along with meto's forcast for autumn, I would not be at all surprised to see the Ice (single year ice) extend into that region (Svalbard) and down the Greenland coast towards Iceland this year. This would probably extend the ice extent in this region, compared to recent years, and may secure plenty of the 'white stuff' for the UK this winter if the NW regime, resposible for the 'multiyear ice drift', persists.

[Gray-Wolf]

http://www.sciencedaily.com/releases/2007/...70913133001.htm

It would now seem as though the north is setting up 'new regimes' of weather and currents which is helping attack the ice from below leading to up to a 50% reduction in thickness compared to 2001.

http://mac01.eps.pitt.edu/Courses/GEOL3909...Maslin_2001.pdf

The above shows a paper outlining the changes during a D.O. event with a kind of see-saw effect (taking hundreds of years to complete) of ice thinning at the pole whilst increasing at the south pole.

This years 'record' sea ice levels in Antarctica would suggest that those processes are happening today but at a much faster rate (tens of years). If you needed further evidence that a new 'driver' is abroad within the climate system then this ,to me, would be it.

I'm sure the 'cycle-ists' would like to view it differently but they must explain the increased speed, in terms of 'natural cycles', of the events to have a chance of convincing me!

[Gray-Wolf]

The first of this seasons images. Note (middle bottom right) the crater of Mount Doom with it's Lava Pool (in black on this 'thermal image) and 'My Crack' to the top left hand corner (the dark line trending to the SE)

Due to the lack of light the images are thermal images and so pick up 'heat Anoms.' ,dark = warm, white=cold.

The ability to see the fracture surface of my crack could indicate sea water intrusion and capillary action up to the near surface. When the sun rises further we can have a proper look at how the winter has treated the shelf edge by Roosevelt island.

[Gray-Wolf]

Now we've got good daylight down under I started to look at the images, courtesy of the MODIS sat

http://rapidfire.sci.gsfc.nasa.gov/realtime/2007261/

to see how 'bad' the sea ice was. All I can see is a mass of fragmented pack (with clear water between) where I expected total ice cover, esp. along the coastal strips. This time last year most of the coastal fringes were solid ice but this year it looks as mashed and mangled as the edges of the polar pack at present.

Obviously I'm just an observer and not an expert but I did expect the record ice extent to be a little more 'joined up' than this patchwork quilt of floes and bergs. Does anyone have any info on the imagers used to predict total ice cover because, by eye (as you'll see if you follow the link) it looks more like a dissipating pack than a growing sheet.

At the end of Aug I'd noted on here that the ice had started to dip but then there was an upturn and rapid build to these record levels. I'm now wondering whether what I saw was the final extent and the 'rapid growth' since was in fact the breakup of the pack and it's 'drifting apart' that was extending it's cover.

It'll be easy to confirm as, now smashed, the ice will ablate at a rapid rate over the next 8 weeks. Could this also signify the fragility of 'single year ice' in both the north and south polar regions?

One to watch?

Edited September 18, 2007 by Gray-Wolf