Arctic ice 'is at tipping point' NOW!

Cashmere · Light Sweet Crude Joined: Mar 27, 2008 Posts: 1971

So if 2005 was less ice than 2008, then the trend is toward more ice going forward?

Sounds like we've moving in the "getting colder" direction.
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Massive Human Dieoff must occur as a result of Peak Oil. Many more than half will die. It will occur everywhere, including where you live. If you fail to recognize this, then your odds of living move toward the "going to die" group.

Gorm

well, THAT would be a tipping-point, but its impossible to draw conclusions over sutch short period of time, ofcourse.

turmoil

rockdoc123 · Light Sweet Crude Joined: May 16, 2005 Posts: 1713

turmoil

Gorm

.[/quote]
another noob Shocked

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U so own the debate when U use arguments on this level.. i think.. or something Wink

threadbear · Expert Joined: Jan 22, 2005 Posts: 7783

KevO · Expert Joined: May 24, 2005 Posts: 2394

turmoil

rockdoc123 · Light Sweet Crude Joined: May 16, 2005 Posts: 1713

KevO · Expert Joined: May 24, 2005 Posts: 2394

DoomWarrior

mos6507

dissident · Heavy Crude Joined: Apr 08, 2006 Posts: 466

It is looking more and more like the IPCC is dead wrong on sea level rise this century. The Greenland ice sheet which appears to be a relic from the past (mentioned in another thread) is likely not to survive if it is surrounded by open water for half the year or longer.

Tanada

Based on this GRAPH the world averaged on a yearly basis around 13 million km^2 of ice in 1970. This was down slightly from the long term average of 13.5, but not remarkable. By 1980 the level dropped to 12.5 and held that level for a few years cycling up and down between 12 and 13 until it broke below 12 for the first time in 1995. From 1995 to 2003 the level held close to 12, mostly on the up side, but then in 2004 something happenned. By 2006, the last year on this graph, the level had fallen to 11.5, and records show it fell even further in 2007. How far I can not state for certain cause I lost the link to the data and have had no luck finding that particular page again. Anyone else have it? It was probably NSIDC or the UIUC.edu data I had before. IIRC 2007 was under 11 for the annual average, but I won't state that firmly unless I can find a link to back it up.

This year, for reasons we have not determined, the Arctic has fallen below every year except 2007 and the Antarctic has trended down as well for the last two weeks. Presumably the fact that nearly all Arctic ice was first year thin ice is the main driving force behind this late season melting which appears to be continuing despite my optimism earlier this week. Almost all Antarctic ice is one year ice and melts back to around 2 Mkm^2 of older more stable ice each southern summer. Last summer Antarctic sea ice grew to over 16 Mkm^2 and set an all time record for the 1979-2007 period, but despite that it still melted back to just over 2 Mkm^2 by late February 2008.

An interesting fact about Antarctic sea ice is, the closer you get to the pole the stronger the polar high is, and the harder it is to melt the sea ice because the constant wind coming off the ice cap helps keep things cold. The constant very cold wind acts as a giant heat sink, sapping the warmth which manages to be absorbed by the Antarctic sea ice. One of the effects we can observe from this is that Antarctic ice shelves appear to be thinning from below rather than from above except on the Antarctic Penninsula where surface melting and pind formation has been observed.

In the Arctic this only happens around the verge of Greenland and in some isolated spots where glaciers ring the basin, for most of the Arctic there is no constant heat sink keeping things cold. One of the things we see as a result is a lot more pond formation in the Arctic closer to the pole. We also see pond formation many places on Greenland itself, partly because southern Greenland is actually hundreds or even thousands of km closer to the equator than any part of Antarctica except for the Penninsula.

In any case we know that roughly 14 Mkm^2 of Antarctic sea ice melts every year and returns during the southern winter. This Arctic summer we have seen just over 10 Mkm^2 sea ice melt away, if we get to the 14 Mkm^2 level at some point that would mean the Arctic would be sea ice free.

The thing I am most curious about, given that I expect to see a sea ice free Arctic summer within my lifetime, is what will this do to the heat balance of the planet? The Antarctic ice sheet is so massive that even if the Arctic were year round ice free it would take a long time to melt away. During that entire period the Antarctic would be acting as a massive planetary heat sink, it takes energy input to melt ice after all, and energy used to melt ice is not availible for heating up anything else. If we ever get to the point where both poles are ice cap free then we will have the real impacts of Global Warming, because only then will they not be absorbing a lot of heat in the latent form of gradually warming ice.

I beleive a polar ice cap free planet is a lot less stable weather wise, people don't seem to graps just how much heat energy the earth currently reflects from Greenland and Antarctica in summer and has absorbed by them in the winter. That ice is not like what you would find in your home freezer, it is a LOT colder and consequently takes a lot more energy input to melt. Sea Ice is much more like your freezer ice, it is cold, but not extrodinarily so.
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