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Do not know about 15 meters, though if Greenland is prime realestate I guess the ice has melted.

How would the world look if Greenland melts? (grinsted)

In the figure on the right you can see the effect of a 7 m increase in sea level would have on the Copenhagen coastline. 7 m is roughly what you would expect if the entire Greenland ice sheet melted.

But 7 meters is also a lot.

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by A swedish kind of death on Tue Sep 8th, 2009 at 04:02:14 AM EST
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March 10, 2009
Greenland ice tipping point 'further off than thought'

Jonathan Bamber, an ice sheet expert at the University of Bristol, told the conference that previous studies had misjudged the so-called Greenland tipping point, at which the ice sheet is certain to melt completely. "We're talking about the point at which it is 100% doomed. It seems quite an important number to get right." Such catastrophic melting would produce enough water to raise world sea levels by more than 6m.

"We found that the threshold is about double what was previously published," Bamber told the Copenhagen Climate Congress, a special three-day summit aimed at updating the latest climate science ahead of global political negotiations in December over a successor to the Kyoto treaty. It would take an average global temperature rise of 6C to push Greenland into irreversible melting, the new study found.

Previous estimates, including those in the recent reports from the Intergovernmental Panel on Climate Change, said the critical threshold was about 3C - which many climate scientists expect to be reached in the coming decades.

"The threshold temperature has been substantially underestimated in previous studies. Our results have profound implications for predictions of sea level rise from Greenland over the coming century," the scientists said.

There is time to make sure the earth doesn't exceed that threshold. 6C - that's a lot.

by Nomad on Tue Sep 8th, 2009 at 04:53:29 AM EST
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We definitely have to stop before 6 (or 5, or 4) degrees. There are no safe levels of warming, but the effects will be managable at 2-3 degrees if there is no methane trigger at those temperatures.

Even if the Greenland ice sheet would 'irreversibly' melt that would take well over 1000 years.

The local impacts of Greenland ice sheet melting have however been underestimated for the Northern Atlantic coasts. 20 centimeters worldwide in a long-term equilibrium may translate in to two or three times that amount in Europe and ten or twenty times in the North-Eastern US and Canada in the short run.

Thermal expansion, especially the local impact of the expansion of the Arctic Ocean, also remains to be modelled with any kind of precision.

by nanne (zwaerdenmaecker@gmail.com) on Tue Sep 8th, 2009 at 06:43:53 AM EST
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Then Greenland might not be so good as real estate investment.

I think it also illustrates the general problem here. The most valuable real estate will be the one with sufficient rain fall (but not to much) close to the sea (but not submerged) and so on. And that is a question of just how the climate patterns will change, which we do not know.

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by A swedish kind of death on Tue Sep 8th, 2009 at 12:52:00 PM EST
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Except we are talking about a 100% certainty of doom for the whole icesheet.

A more reasonable threshold would be 50% chances of losing around a third. Because that would be enough to be a disaster. Actually 10% chances would already be rather a lot.

Earth provides enough to satisfy every man's need, but not every man's greed. Gandhi

by Cyrille (cyrillev domain yahoo.fr) on Tue Sep 8th, 2009 at 03:04:45 PM EST
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I believe a sea level rise of 15 meters was brought up by you in this discussion out of the blue, and I questioned that. My point remains that this figure appeared out of thin air with no particular reference to anything, and no time frame.

We can continue quibling what projected sea level rise would be but Climate Doom in the vogue of "we're all gonna die because of Greenland melting" is not very rational and mostly acts defeatist. Hence my reply. Now we´re talking.

by Nomad on Wed Sep 9th, 2009 at 03:50:32 AM EST
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Not out of thin air. The premise was that Greenland had melted -it was said to be prime real estate.

Greenland cannot melt without a lot of Antarctica going (West Antarctica is probably a gonner before 2050, let alone in the longer run).

And that means at the very least 15m, without taking thermal expansion into account. And even more in Europe initially.

Earth provides enough to satisfy every man's need, but not every man's greed. Gandhi

by Cyrille (cyrillev domain yahoo.fr) on Wed Sep 9th, 2009 at 04:24:16 AM EST
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No one talked about Greenland's ice melting completely prior to you bringing up 15 meters. So the premise may have been yours at first, and may not have been communicated that well. In any case, it wasn't clear to me.

Part of the reason why we're talking past each other is because different time frames are colliding.

If 100% irreversible melting of Greenland's ice will occur (at, say, 6C temperature increase), this will not happen in the short term, and probably not this century either. In the case of water management, one cannot plan much further today. So that's it, and the rest is all what may be, and not relevant (yet) from an adaptation point of view.

On the longer time frame, the one you seem to be using, it's interesting stuff, but also speculative and not that helpful. It's mostly done by a lot of academics quibbling, or people getting distracted by doom scenarios because tsunamis sell enough prints. That's all there is, and nothing more. 15 meters? It could be 20. So what as long as we don't know when it will happen?

by Nomad on Wed Sep 9th, 2009 at 05:14:33 AM EST
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I said nothing about Greenland melting completely or becoming prime estate. I said it was a climate winner. Any heating of that dreadful place will make it a nicer place to live, and will make petroleum and mineral exploitation less of a hassle.

Peak oil is not an energy crisis. It is a liquid fuel crisis.
by Starvid on Wed Sep 9th, 2009 at 12:35:33 PM EST
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So raising the sea wall another 5-7 meters would be no big problem?  How high are they now?  6C is not an unreasonable average ambient increase, given the collective ability of our species to respond to what are perceived as distant threats.  I understand that 6C is what we can expect unless current actual trends are significantly altered, and these trends have not yet really begun to be altered, especially outside of Europe.

Even if we reach 6C there is no certainty as to how long it will take for the ice cap to melt.  But there is also no certainty that the ice cap will not have already melted by then.  And then large scale ice melt from Greenland could conceivably alter the deep saline current and the Gulf Stream.  This could cause ice sheets to begin accumulating in northern Europe.  It might slow down the melting of Greenland, but it would hardly be an advantage to northern Europe.

There is only really one way to verify if the models are accurate and we don't want to go there.  To me the prudent thing is to assume a worst case and work to avoid it.  At worst we will have given people employment doing things that turned out not to have been necessary, but the world as we know it will have survived substantially.  But that is not how finance operates and, as we know, finance runs the world.

"It is not necessary to have hope in order to persevere."

by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Tue Sep 8th, 2009 at 07:18:57 PM EST
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is an absolutely massive amount of temperature increase in geological perspective. Just saying. We'll need to go back far, far back to a time where we think the earth was that warm. From the top of head, probably into the Paleocene.

6C is a convenient number to quote, but establishing a figure on climate sensitivity has been and still is the holy grail of climate science, and it's not settled. I'm agnostic on what it will be. To me, the number matters more for establishing proper adaptation gaols, than that it acts as a stimulus for switching to a non-carbon society.

Right now, the IPCC projection of sea level rise until 2100 range from a few cms to 1 meter - a figure which has been corroborated by younger studies. However, current sea level rise will have to accelerate a lot to find itself in the higher end of that bracket. Even so, in the medium long term (decades to 1 century), the Netherlands has little to worry.

by Nomad on Wed Sep 9th, 2009 at 04:14:28 AM EST
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No serious scientist I know of has talked about anything worse than 2 metres in 100 years. And that is if the global warming stuff is actually correct and peak oil/gas/coal isn't real.

Peak oil is not an energy crisis. It is a liquid fuel crisis.
by Starvid on Wed Sep 9th, 2009 at 12:38:04 PM EST
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