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Post by sigurdur on Jan 15, 2015 2:06:55 GMT
I'd just been reading this so ta for the vid presentation! The scientist likens the surface of Greenland to 'Swiss Cheese' and the subsurface to a sponge. That sodden layer, in the snow layers directly above the ice does trouble me as surely any 'steep' profiles raise the prospect of sudden failure at that layer and slip down into lower, warmer levels? We know that there is a saddle/lobe function of ice sheet melt so this may well be the function that takes mass from sub zero temps elevations down into warmer valleys? Been watching the Sat output from 'Wokingham Weather' ( primarily to see the extent of the scalloping in Lincoln caused by Nares still being in full flow) and see that Beaufort is not in a pretty state? has this move toward smaller floes ( instead of contiguous ice cover) lead to us seeing this disruption of the ice over winter ( like a grenade or chocolate bar breaking apart)? Graywolf: I fully expect 90%+ of the Greenland Ice sheet to melt. That is what has happened during previous interglacials, so don't expect this one to be any different. In MIS-6, by this time frame most of the glacier had departed. The Holocene seems to be a slow burn relative to previous hot times. As far as Arctic Ice, I agree. The full flow of ice out of Nares at this time is not conducive to a good summer pack. Time will tell.
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Post by sigurdur on Jan 15, 2015 2:07:58 GMT
Thanks for finding an alternative link Ratty. The link worked this morning, but the owners must have changed it a bit. Thanks again. I hate pages that did exist that don't exist at present.
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Post by sigurdur on Jan 19, 2015 19:17:22 GMT
www.washington.edu/news/2014/05/07/greenland-melting-due-equally-to-global-warming-natural-variations/The rapid melting of Greenland glaciers is captured in the documentary “Chasing Ice.” The retreat of the ice edge from one year to the next sends more water into the sea. Now University of Washington atmospheric scientists have estimated that up to half of the recent warming in Greenland and surrounding areas may be due to climate variations that originate in the tropical Pacific and are not connected with the overall warming of the planet. Still, at least half the warming remains attributable to global warming caused by rising carbon dioxide emissions. The paper is published May 8 in Nature.
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Post by sigurdur on Jan 23, 2015 1:04:08 GMT
Someone had mentioned the See/Saw effect of temperatures between the Arctic and Antarctic a while back. I knew I had read something, and just came across it. www.sciencemag.org/content/291/5501/109.short In general, Antarctic temperatures increased gradually while Greenland temperatures were decreasing or constant, and the termination of Antarctic warming was apparently coincident with the onset of rapid warming in Greenland. This pattern provides further evidence for the operation of a “bipolar see-saw” in air temperatures and an oceanic teleconnection between the hemispheres on millennial time scales.
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Post by cuttydyer on Jan 23, 2015 5:48:24 GMT
Someone had mentioned the See/Saw effect of temperatures between the Arctic and Antarctic a while back. I knew I had read something, and just came across it. www.sciencemag.org/content/291/5501/109.short In general, Antarctic temperatures increased gradually while Greenland temperatures were decreasing or constant, and the termination of Antarctic warming was apparently coincident with the onset of rapid warming in Greenland. This pattern provides further evidence for the operation of a “bipolar see-saw” in air temperatures and an oceanic teleconnection between the hemispheres on millennial time scales. The see/saw Antarctic Arctic effect is captured in this graph from the 1990 IPCC report (page 224): I predict the AGW crowds focus will see saw from the Arctic to the Antarctic when Arctic ice returns above mean & Antarctic ice drops below. 1990 IPCC report link: www.ipcc.ch/ipccreports/far/wg_I/ipcc_far_wg_I_full_report.pdf
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Post by nautonnier on Jan 23, 2015 12:27:00 GMT
It would be nice if they were logical, but as the Antarctic ice remains at record levels, there are those 'fearful' of the amount of melting in the Antarctic. Remember that was the purpose of the 'ship of fools' to show how severe the ice-loss was.
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Post by nautonnier on Jan 24, 2015 18:08:32 GMT
The above also illustrates the idea of poles alternating in extent, would be nice if we could trace this further back in history.... A response to a post at WUWT gives some more discussion on the 'polar seesaw' but with a different slant.
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Post by acidohm on Jan 24, 2015 20:52:13 GMT
Yes...It doesn't give confidence in an understanding of a clear cut relationship of Arctic v antartic. Nice to read more points of views on the idea,
I do feel there's something to it. ..However sometimes looking more at the climate just teaches you how little you know!
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Post by sigurdur on Feb 1, 2015 17:29:41 GMT
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Post by graywolf on Feb 1, 2015 17:57:16 GMT
An ice cap in the high Arctic has lost what British scientists say is a significant amount of ice in an unusually short time. It has thinned by more than 50 metres since 2012—about one sixth of its original thickness—and the ice flow is now 25 times faster, accelerating to speeds of several kilometres per year. Over the last two decades, thinning of the Austfonna ice cap in the Svalbard archipelago—roughly half way between Norway and the North Pole—has spread more than 50km inland, to within 10km of the summit. From; www.truthdig.com/report/item/arctic_glaciers_galloping_melt_baffles_scientists_20150131?And the abstract; onlinelibrary.wiley.com/doi/10.1002/2014GL062255/abstractShows you what removing sea ice from around Svalbard will do ( apart from starving the Polar Bears that is!). So what happens when the ocean terminating glaciers around Greenland begin similar collapses ( as the warm bottom ocean waters eat away the base beyond the 'lip' and so is then is able to flow into the inland basin?) Past melts have all show 'melt water pulses' so is this one of the ways we will see such this time around?
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Post by sigurdur on Feb 1, 2015 18:29:17 GMT
Graywolf: The march of time during an interglacial is what provides the energy to melt the ice.
Why would one expect the Holocene to be different in glacial deterioration than past periods of warmth?
Ice melts when it is warm, it freezes when it is cold. It is really as simple as that isn't it?
We are in a warm epoch. Predictable things happen. Melting of the Greenland ice cap, along with the WP of Antarctica is a known happening. No matter who you want to blame, AGW or whatever, it IS going to happen as the length of the Holocene continues.
During MIS-11 large areas of Antarctica were ice free. We also know that Greenland was ice free.
The Eemian, the last interglacial, was shorter than MIS-11, but both periods resulted in similar ice changes.
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Post by graywolf on Feb 3, 2015 10:02:36 GMT
Current orbital forcings favour a slow cooldown across the far north and indeed we saw 1,000yrs of cooling across the far north which ended a little over 100yrs ago and reversed into a rapid warming trend? Why should we see this 'against the grain' behaviour siggy? and why do we suddenly see this ice cap enter such a rapid melt phase?
We lost the ice shelfs on the north shore of Ellesmere island (now just remnant chunks scattered along the north shore) over the past century producing some of the largest ice islands ( big enough to be mistaken for land and also used as military 'look out posts' during the cold war) ever witnessed in the Arctic. again those collapses were over a period where orbital forcings were such a to promote cooling across the far north so what went wrong?
You cannot keep using the 'we're in an interglacial' line without reffering to just where we are in that interglacial with regards to the major drivers of glaciation.
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Post by icefisher on Feb 3, 2015 10:27:19 GMT
Current orbital forcings favour a slow cooldown across the far north and indeed we saw 1,000yrs of cooling across the far north which ended a little over 100yrs ago and reversed into a rapid warming trend? Why should we see this 'against the grain' behaviour siggy? and why do we suddenly see this ice cap enter such a rapid melt phase? We lost the ice shelfs on the north shore of Ellesmere island (now just remnant chunks scattered along the north shore) over the past century producing some of the largest ice islands ( big enough to be mistaken for land and also used as military 'look out posts' during the cold war) ever witnessed in the Arctic. again those collapses were over a period where orbital forcings were such a to promote cooling across the far north so what went wrong? You cannot keep using the 'we're in an interglacial' line without reffering to just where we are in that interglacial with regards to the major drivers of glaciation. Well I don't have your answer other than to point out it appears as if its not unusual.
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Post by sigurdur on Feb 3, 2015 14:20:03 GMT
Current orbital forcings favour a slow cooldown across the far north and indeed we saw 1,000yrs of cooling across the far north which ended a little over 100yrs ago and reversed into a rapid warming trend? Why should we see this 'against the grain' behaviour siggy? and why do we suddenly see this ice cap enter such a rapid melt phase? We lost the ice shelfs on the north shore of Ellesmere island (now just remnant chunks scattered along the north shore) over the past century producing some of the largest ice islands ( big enough to be mistaken for land and also used as military 'look out posts' during the cold war) ever witnessed in the Arctic. again those collapses were over a period where orbital forcings were such a to promote cooling across the far north so what went wrong? You cannot keep using the 'we're in an interglacial' line without reffering to just where we are in that interglacial with regards to the major drivers of glaciation. Graywolf: Orbital forcings are a nice back drop, but they have never explained temperature variability within interglacials. Icefishers graph is correct, showing warming and cooling periods while the orbital parameters had little change. The march of retreating ice, far as I can read, is pretty steady during interglacials. The rebound to an interglacial is sudden, that we can agree on I hope? That 1,000's of years of cooling is presented where? I have not been able to find what you state, but you may have a source to share with us?
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Post by sigurdur on Feb 3, 2015 14:23:04 GMT
In fact, there are several important holes in the Milankovitch cycles yet to be explained, which I am pretty sure you know.
IN fact, there is a thread on this board regarding some of those holes. Orbital forcings have to be important, but they are only a small part of the overall puzzle.
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