Most interesting

The threat of the Greenland ice sheet slipping ever faster into the sea because of warmer summers has been ruled out by a scientific study.

Until now, it was thought that increased melting could lubricate the ice sheet, causing it to sink ever faster into the sea. The issue was a key unknown in the landmark 2007 report from the Intergovernmental Panel on Climate Change, which pinned the blame for climate change firmly on greenhouse gas emissions from human activities.

….

Researchers had feared that more melting from the surface of the ice in hotter years would in turn provide more meltwater for a slippery film at the sheet\’s base. More melting would mean more slippage and a greater rise in the sea level.

But they discovered that, above a certain threshold, the slipping began to slow. On-the-ground studies and work done on alpine glaciers suggest that higher volumes of meltwater form distinct channels under the ice, draining the water more efficiently and reducing the formation of a lubricating film.

The Greenland ice sheet studied by Shepherd\’s team is up to 1,000m (3,280ft) thick. If the entire ice sheet melted, sea levels would rise by a catastrophic seven metres, but this is likely to take 3,000 years if warm air blowing over the ice is the only way in which the ice melts.

More evidence that what we face is not an immediate and catastrophic problem, but a chronic and long term one.

Greenland melting in full is now pencilled in for 5,010 AD*. Rather a lot of things will change by then: while I\’ll not be around to see it of course I\’d rather expect there to be a Space Elevator by then for example.

What amuses, I have to say though, is that they\’ve reached this conclusion by noting that water flowing downhill, in quantity, seems to form streams and rivers rather than flowing as a sheet down the side of the hill.

You don\’t say?

* I have a feeling that they\’ve got that 3,000 wrong and that it might actually be 300 but it\’s still not an immediate problem.

12 comments on “Most interesting

  1. As a sign of the quality of the science on the “global warming” by those who aren’t scientists read this. Link is to DM, but it’s been mentioned in HuffPost and elsewhere that some people are thinking it’s true

    http://www.dailymail.co.uk/sciencetech/article-1346936/The-sun-rises-days-early-Greenland-sparking-fears-climate-change-accelerating.html

    Here they are saying that because the ice is melting it means that it’s lower and therefore the sun can peek over the horizon two days early! So much utter crap it’s unbelievable!

  2. With reference to your footnote, the average thickness of the Greenland icesheet is 2,000 m or so, so to melt that in 300 years would require summer melting of about 7m per year – I think they have the order of magnitude right.

  3. “they’ve reached this conclusion by noting that water flowing downhill, in quantity, seems to form streams and rivers ”

    Which of course was subject to all doubt until some scientists noticed it . . .

  4. Re SMBL @1
    Crap isn’t quite the word for it.
    Just tried playing around with simple geometry to see how much the ice would have to drop by to affect sunrise by 2 days & unless there’s something wrong with my calcs it’s in the 100′s of metres.
    What would affect sunrise noticeably is refraction if they’re talking about the first sign of the sun’s disc. Simple boundary of low/high pressure would achieve that. & I’ve actually seen that phenomenon watching dawn over the Med. Clear morning & the first sight of the sun is a brilliant pinpoint of light. Sometimes that pinpoint flashes on & off for a few seconds before the sun is high enough to overcome the effect.

  5. On the subject of the melting at the base of the icecap, I can remember reading years ago how the thermal pulse from the end of the last ice age would only now be reaching the base of the Antarctic ice cap & whether that would result in increased ice movement. 5Km in 10K years.
    Of course that was before the Global Warming fantasy took over scientific discussion.

  6. Prince Charles has just released a press statement, “only 36,000 months to save the Greenland ice sheet”, emergency measures, suspension of democracy, punitive taxation, subsistence farming etc NEEDED NOW!

    Tim adds: In further news, Andrew Simms has just won a 36,000 month contract with The Guardian to tell us of our movement towards this tipping point.

  7. Timmy, *when* are you going to learn not to pay any attention to the “science” (or, come to that I suspect, economics) in the newspapers? IPCC 2007 is freely available; you should read that.

    The boring answer is that the taking ~3000 years to fully melt the Greenland ice sheet has always been the std answer. People play games to try to see if it could be got rid of faster but they’ve never convinced many (I mean, scientists reading the literature. Gullible journo’s, blog-writers and blog-readers are another matter).

    IPCC 2007 is http://www.ipcc.ch/publications_and_data/ar4/wg1/en/contents.html

    There is a summary of the SLR stuff at http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-es-8-sea-level.html

    Quote:

    Thermal expansion is the largest component, contributing 70 to 75% of the central estimate in these projections for all scenarios. Glaciers, ice caps and the Greenland Ice Sheet are also projected to contribute positively to sea level… Further accelerations in ice flow of the kind recently observed in some Greenland outlet glaciers and West Antarctic ice streams could substantially increase the contribution from the ice sheets. For example, if ice discharge from these processes were to scale up in future in proportion to global average surface temperature change (taken as a measure of global climate change), it would add 0.1 to 0.2 m to the upper bound of sea level rise by 2090 to 2099… Understanding of these effects is too limited to assess their likelihood or to give a best estimate.

    Scary enough for you?

    Tim adds: But we do keep hearing it from Mark Lynas, Geoffrey Lean, G. Monbiot, Caroline Lucas etc.

    My battle isn’t at all with hte science, as you know. It’s with what some idiots are proposing we try to do about it. Those idiots being Caroline Lucas, G. Monbiot, well, you get the picture.

  8. A simple PVT calculation would suggest that water is ALWAYS at the bottom of glaciers. Since V can’t increase, T must. There is a kicker in the water phase transition of course, the latent heat of melting. But the basic point is that all glaciers in zones where humans live are already lubricated by water between the glacier and the ground.
    Thanks SBML. Did you see the comment from the Greenlander who pointed out that the horizon at Susqevokboolok is actually a bare mountain?
    And what happened to the theory that glacier melt would cause Greenland to heave?

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