Lennart,
I do not know that answer to your question, but I am re-posting the following information from the Paleo thread in the Antarctic folder because as we now have evidence that the WAIS is already in the process of collapsing, the linked reference (with an open access pdf) shows that a collapse (or partial collapse as was the case for MWP 1A) of the WAIS can drive Arctic amplification (and associated permafrost degradation) by pushing warm ocean water through the Bering Strait into the Arctic Ocean:
Martin Melles, Julie Brigham-Grette, Pavel S. Minyuk, Norbert R. Nowaczyk, Volker Wennrich, Robert M. DeConto, Patricia M. Anderson, Andrei A. Andreev, Anthony Coletti, Timothy L. Cook, Eeva Haltia-Hovi, Maaret Kukkonen, Anatoli V. Lozhkin, Peter Rosén, Pavel Tarasov, Hendrik Vogel, & Bernd Wagner, (2012), "2.8 Million Years of Arctic Climate Change from Lake El’gygytgyn, NE Russia", Science, Vol. 337 no. 6092 pp. 315-320, DOI: 10.1126/science.1222135
http://bhap.artsrn.ualberta.ca/images/uploads/BHAP_Papers_2012/Melles_et_al._Science_2012.pdfABSTRACT
"The reliability of Arctic climate predictions is currently hampered by insufficient knowledge of natural climate variability in the past. A sediment core from Lake El’gygytgyn in northeastern (NE) Russia provides a continuous, high-resolution record from the Arctic, spanning the past 2.8 million years. This core reveals numerous “super interglacials” during the Quaternary; for marine benthic isotope stages (MIS) 11c and 31, maximum summer temperatures and annual precipitation values are ~4° to 5°C and ~300 millimeters higher than those of MIS 1 and 5e. Climate simulations show that these extreme warm conditions are difficult to explain with greenhouse gas and astronomical forcing alone, implying the importance of amplifying feedbacks and far field influences. The timing of Arctic warming relative to West Antarctic Ice Sheet retreats implies strong interhemispheric climate connectivity."
See also:
http://www.newscientist.com/article/dn21959-loss-of-antarctic-ice-could-trigger-superinterglacial.html#.VKxIOqPTnIUExtract: " At least eight times in the last 2.8 million years, the Arctic experienced super-interglacials – periods in which summers there were 5 °C warmer than they are today.
Climate models cannot explain these unusually warm spells, but there could be an unexpected cause: the collapse of the West Antarctic ice sheet (WAIS), on the other side of the planet. The sheet could collapse again as the world warms, perhaps heralding super-interglacial number nine.
The evidence for the super-interglacials comes from a sediment core drilled from the bed of Lake El'gygytgyn in north-east Russia by Martin Melles of the University of Köln in Germany, and his colleagues.
Toasty warmThe Arctic ice sheets have been advancing and retreating for the last 2.6 million years, as temperatures fell and rose. Warmer periods – including the one we now live in – are known as interglacials. The Lake El'gygytgyn core confirms that Arctic temperatures during eight of these periods were on average 4 to 5 °C warmer than in the region today. "That's really a lot," says Melles.
What triggered these super-interglacials? Earlier studies hinting that they occurred encouraged Paul Valdes at the University of Bristol, UK, to try to find out. Last year he discovered that standard climate models couldn't simulate them (Journal of Quaternary Science, DOI: 10.1002/jqs.1525).
Melles ran into the same problem. He used a state-of-the-art climate model that included key positive feedbacks, such as vegetation moving north and thus absorbing more heat. But he could not trigger a super-interglacial in his simulations.
He turned to sediment records from Antarctica for further clues. These records suggest that the WAIS disintegrated during each of the super-interglacials.
All around the world
Despite being half a world away, the collapse of the ice sheet might be the trigger for an Arctic super-interglacial, says Melles. As the WAIS disintegrates, it would raise global sea levels by about 5 metres. This would push more warm water from the Pacific Ocean through the Bering Strait into the Arctic Ocean, warming the Arctic region.
Valdes agrees such a process could well be important, particularly as it was not included in the models he studied last year. So a collapsing WAIS would not just drive up sea levels, it might also heat up the Arctic. The $64,000 question is, will it collapse again in the near future?
"What we see today is a dramatic decrease of the WAIS," Melles says. Some scientists think it will start to break up this century. But Melles says it could be centuries before the whole thing goes, and the effects would then take time to reach the Arctic.
"I don't think we know what it will take to lose the WAIS," says Valdes, "but if it goes, it would have climate consequences for the whole globe."