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47 comments on Atlantic Circulation Changes

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FoxFolktale on November 30, 2005 - 10:13pm Permalink | Subthread | Parent | Comments top
Interestingly, the Greenland ice sheet is melting at the edges, and thickening along the interior, just what it is supposed to do as a result of global warming:

http://www.sciencedaily.com/releases/2005/11/051107080830.htm

In fact, 2005 looks to feature the greatest amount of melting of the edge of the ice sheet in Greenland in about 30 years (or more):

http://cires.colorado.edu/science/groups/steffen/greenland/melt2005/

There is a great book called the Two Mile Time Machine, by Richard Alley, that discusses the Greenland Ice Core Project, and the study of past failures of the ice sheet, and the ensuing almost instant climate change. This failure is thought to be one of the primary drivers in the disruption of the warm, salty conveyor belt that keeps Europe's western reaches so mild.

Oh, and if the ice sheet does melt, how long can you tread water?:

http://news.nationalgeographic.com/news/2004/04/0408_040408_greenlandicemelt.html

The least of our worries indeed!

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Stuart Staniford on December 1, 2005 - 12:33am Permalink | Subthread | Parent | Comments top
Well, but we have Cat 4 and 5 hurricanes beating the shit of us every year now. At least at the moment, scientists have not predicted massive sea-level rise this century. (However, I have noticed a disturbing trend for things to go faster than the climatologists predict - including this latest news on the circulation).
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GreyZone on December 1, 2005 - 1:03am Permalink | Subthread | Parent | Comments top
The climatologists cannot agree because the models are not good enough yet. Here's one climatologist saying the Greenland ice sheet could be gone in 50 years tops. And here's another study saying Greenland's ice sheet will take over 1000 years to melt. And here is a report that says the melt is accelerating over just the last few years.

I think the models are poor enough at the present time that making predictions is hazardous but we can see the trendlines. And the geologic record tells us that climate change happens fast (less than a decade). In fact, here's an article discussing the process that scientists went through in the 20th century as they came to grips with the evidence of abrupt climate change.

We simply do not know where we are on the trendline from warm age to the next ice age. And by pushing the climate rapidly into unstable states, we may be accelerating things into even less stable conditions.

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clifman on December 1, 2005 - 10:38am Permalink | Subthread | Parent | Comments top
Err... here's the second paragraph from your first link:

Jonathan Gregory, a climatologist at the University of Reading, UK, says global warming could start runaway melting on Greenland within 50 years, and it will "probably be irreversible this side of a new ice age". The only good news is that it a total meltdown is likely to take at least 1000 years.

Hyperbole and exaggeration don't help.  Do I think the models are weak enough that Greenland Ice might melt faster than predicted?  Sure.  But this guy isn't saying it will be "gone in 50 years tops"

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GreyZone on December 1, 2005 - 1:11pm Permalink | Subthread | Parent | Comments top
Mea culpa. Yet a significantly wide range of estimates still persists.

Professor Slawek Tulaczyk and Ian Howat, of the Department of Earth Sciences at the University of California, Santa Cruz, say that new melt evidence could easily cut previous melt estimates in half.

Yet here, we have another team saying the melt time is in "thousands" of years.

And here are scientists who aren't even sure the Greenland cap is melting at all.

The estimates reported seem to have wide variance (though not as wide as I originally thought). And further, none of the existing global warming models of which I am aware accounted for the sudden increase in melt over the last 5 years. Most climatologists seem to have been taken by surprise, as I noted previously, by the rapid increase in melt rate which was not accounted for by existing models.

I think my point remains - our models are incomplete and at this stage inevitably subject to errors. Also, at this point, the errors have all been too cautious. Given the immense potential impacts of these changes, both now and in the future, I think we are being foolish to ignore the longer term trend. But hey! The economists assure us that the market will solve everything so be happy, and spend, spend, spend, right?

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porsena on December 1, 2005 - 12:59pm Permalink | Subthread | Parent | Comments top
No Greenland controversy here.  The first two links use different words to describe results of the same study, and the third link is in agreement.  

Gregory's model, the subject of the first two links and referred to in the third, suggests that as ice is lost, the ice cap in central Greenland, high enough today to cause appreciable snowfall, would end up at lower elevations where the air is warmer. A feedback mechanism ensues in which less snowfall and more rain would cause the ice to disappear more quickly than it was being replaced, leading in turn to further drops in elevation.  A different approach (Mitrovica et al, Nature 409:1026,(2001)) suggests melting of the Greenland ice complex over the last century has already contributed the equivalent of 0.6 mm per year of sea-level rise.

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