Faster than we think

[pscot]

http://www.motherjones.com/blue-marble/2009/11/ice-age-froze-europe-months

Freako-frakkin-nomics notwithstanding, climate change is a thing of violent swiftness. New research indicates it took only months for Europe to freeze solid 12,800 years ago.

The most precise analysis yet of the onset of the "Big Freeze" reveals that Europe froze not in a decade—as previously thought from analysis of Greenland ice cores—but in less than 12 months.The Big Freeze was triggered by the slowdown of the Gulf Stream. It terminated the Clovis culture, the dominant culture in North America at the time. Once triggered, the cold persisted for 1,300 years.

New Scientist reports on the research of William Patterson of the U of Saskatchewan whose group studied a mud core from ancient Lough Monreagh in Ireland, slicing layers 0.5 to 1 millimeter thick to study three-month intervals. No prior measurements from this period have approached such fine detail.Turns out, at the start of the Big Freeze temperatures plummeted and lake productivity ceased within months or a year at most. Patterson presented the findings at the BOREAS conference in Finland. According to him (via New Scientist):

"It would be like taking Ireland today and moving it up to Svalbard."


We know the Big Freeze was triggered when a glacial lake covering most of northwest Canada burst its banks and poured into the North Atlantic and Arctic Oceans, diluting oceanic salinity (I wrote of fears of this in MoJo's The Fate of the Ocean) and rerouting the oceanic currents that deliver climate to the Northern Hemisphere:

Two studies published in 2006 show that the same thing happened again 8,200 years ago, when the Northern hemisphere went through another cold spell. Some climate scientists have suggested that the Greenland ice sheet could have the same effect if it suddenly melts through climate change, but the 2007 report of the Intergovernmental Panel on Climate Change concluded this was unlikely to happen this century.Well, that's out of date. We already know Greenland is turning to slush frighteningly fast......

[XemaSab]

1. .

[Nederland]

2. How fast is fast?

At the current rate, how many years will it take for the Greenland ice sheet to completely melt?

The Greenland ice sheet contains 2.85 million km³ of ice (http://en.wikipedia.org/wiki/Greenland_ice_sheet).

The ice is melting at a rate of 240 km³ a year (http://www.dtu.dk/English/About_DTU/News.aspx?guid={AD9CEB93-85CC-48B3-B640-34D9FA8BF5F0})

A little simple math tells us that at the current rate, it would take 11875 years to completely melt the whole ice sheet. Even if you assume that the ice starts melting at ten times its current rate, that is still over a thousand years. I think therefore comparisons to what happened when the glacial lake covering most of northwest Canada burst its banks are not apt. In that case we are talking about millions of km³ of fresh water pouring into the ocean in a matter of weeks, not millennium.

[kristopher]

3. Why is that relevant?

Are you claiming that the entire mass of Greenland's ice must melt to effect the change being speculated about or did you just not even bother to read the article before replying?

The change being pointed to was a result of changes in the Gulf Stream caused by a sudden large influx of cold water. From the article, "Daily satellite images of Greenland's glaciers reveal the break-up of two of its largest glaciers in the last month. A massive 11-square-mile piece broke off the Petermann Glacier in northern Greenland between July 10th and by July 24th. That's half the size of Manhattan. Between 2000 and 2001 the same glacier lost 33 square miles of floating ice.

What worries researchers from the Byrd Polar Research Center at Ohio State University is what appears to be a massive crack further upstream. A break-up there would doom 60 square miles, or one-third of what's left of the massive ice field..."

[Javaman]

4. The second half of this century is going to be very interesting.

but the run up will be devastating as people flail about trying to blame someone rather than take responsibility. Oh wait, that's already happening. :(

[Nederland]

5. The comments in the article are interesting

I wonder if the author of this piece is aware that the IPCC concluded that while Greenland melt water might slow down the THC slightly resulting in lowering temperatures, the effect would be overwhelmed by the overall trend toward warmer temperatures.

[kristopher]

6. I'm sure they are.

I'm also sure your comments are those of a climate denier dredging up irrelevant noise in an attempt to obscure the message. I'm not a fan of alarmism but this is a real threat that can have extreme near term consequences.