Nature - 3,000 GT Cumulative Atmospheric Carbon May Be Threshold For Irrevocable Greenland Melt

[hatrack]

EDIT

Sylvie Charbit at the Laboratoire des Sciences du Climat et de l'Environment, Gif-sur-Yvette, France, and colleagues simulated the long-term stability of the Greenland ice sheet under various carbon dioxide emissions scenarios. Under scenarios where cumulative emissions are less than 2,500 gigatonnes of carbon dioxide (GtC), the ice sheet melts only partially and even begins to recover within several thousand years. However, above 3,000 GtC, melting is rapid and complete, and persists for tens of thousands of years. The researchers did not include other greenhouse gases such as methane and nitrous oxide in the model, which suggests that their estimates of the carbon threshold are conservative.

Although current cumulative carbon dioxide emissions are on the order of 350 GtC, total emissions may reach 2,480 GtC by AD 2100 under worst-case scenarios — so unless emissions are curbed, runaway melting of Greenland may be triggered in the coming centuries.


EDIT

http://www.nature.com/climate/2008/0808/full/climate.2008.73.html

[Hydra]

1. The ice is already melting

And if we cut down on the particulate air pollution, the general temp might rise as much as 10%.

"Conservative Estimate" is a gross understatement.

[DCKit]

7. And as the ice melts, the tundra melts, releasing methane.

I've seen estimates that put methane between 13 and 40 times more "powerful" than CO2 as a greenhouse gas.

Even 13x is going to suck hugely, given that there are tens of billions of tons of methane locked up in the tundra.

[phantom power]

2. "Cumulative" seems like an odd way to label these scenarios.

A cumulative emissions figure doesn't (by itself) tell us anything about what concentration is achieved in the atmosphere.

[hatrack]

3. Not having access to the whole article (alas!) there may be further details

I would assume that he's talking about cumulative accumulation since, oh, 1750 as a baseline, but I don't know that.

[XemaSab]

4. So we're going to lose Greenland in 100 years?

Somehow, I'm skeptical...

[kestrel91316]

5. Me, too. I'm thinking 25.

Just call me "Little Mary Sunshine".

[XemaSab]

6. Better than

"Betsy Weatherhead." :P

[Indenturedebtor]

8. Don't worry. When the North Atlantic Current shuts down

We'll have another iceage! :woohoo:

Better go see Yurp and NYC now!