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Adam Ash
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I guess, as a mechanism which could lead to an abrupt Wadham's-style ending, there could be a levelling of the thermal gradient across the ice pack. I imagine, of old, that ice tended to melt from the edge of the pack inwards towards the pole, and the ice itself was colder the further north it lay. But these days, with melt ponds at 90 North, clearly the whole ice mass is getting warmer through its full thickness, even if it is still below 0C and pretending to hold hands. Could there come a point where the majority of the ice pack is so close to having absorbed all the latent heat it needs to get it up to the edge of melting, whereby all it needs is the final (massive) thermal shove to complete the job and become liquid. I know the heat required to get from ice at 0C to water at ditto is a lot, but the more ice that is closer to 0C then the more a decent heat wave could wipe out a huge extent very quickly. The buoys don't give me enough coverage to check this, but the levelling of the thermal gradient across the latitudes, and in depth, would seem to be a reasonable mechanism to consider as a way to position large extents for sudden extinction without the effect being obvious from just extent or area observations.
Re Methane... This just in from off the coast of New Zealand... '...Surprisingly, the team discovered that every area of carbonate rock and every fault seen on the seafloor was expelling gas, and in total, they calculated there were near to 766 individual gas flares within the area. "That was really way beyond expectations," Dr Mountjoy told the Herald tonight. "Flares can occur in these kind of environments but seeing them in that kind of density is highly unusual - and we've certainly found nothing like it in New Zealand before."' http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11441247
Toggle Commented Apr 30, 2015 on EGU2015, my impressions at Arctic Sea Ice
'Arctic sea ice may be more resilient than many observers recognise.' Yeah, rite... From those two data points a straight line gives: Year October Vol 2013 8800 2014 7500 2015 6200 2016 4900 2017 3600 2018 2300 2019 1000 2020 -300 2020 she's all over rover! Then to say '... there is no evidence to indicate a collapse is imminent.' 2020? Not imminent. OK. Obviously its not quite as simple as that, but the statement rather smacks of a degree of cognitive dissonance, no?
Toggle Commented Dec 18, 2014 on In the meantime: CryoSat at Arctic Sea Ice
Thanks for the update Neven. I'm always a tad puzzled by your use of the term 'rebound' in relation to the minor annual wriggles we are seeing around the overall trend of ice volume decline. With respects, the term smacks of wishful thinking, or King Canuteism, I'm not sure which. The Big Picture is that present annual minimum Arctic sea ice volume is currently ten thousand cubic kilometres less than it was when we started to take notice in the late 1970s. http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAprSepCurrent.png When that 10km3 loss is considered in the context of the recent observed minimum of just under four thousand cubic kilometres its clear that the Arctic and hence the climate (particularly the climate of the Northern Hemisphere) is in very 'hot water' indeed. Should the annual minimum ever get back above its historic 15,000 km3 norm I would accept use of the term 'rebound', but until then (I suggest we will need to wait for several million years, if ever), its not a 'rebound', its a just a twitch from a dying ice block.
Toggle Commented Nov 11, 2014 on PIOMAS November 2014 at Arctic Sea Ice
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Nov 11, 2014