Horace Heffner wrote:
> The immediate problem is passing the tipping point where the methane is > released. Methane is 20 times more effective than CO2 at the greenhouse > effect, and is lighter than air. It eventually oxidizes into CO2, but > at high altitude. High altitude water vapor is a very effective > greenhouse gas, and at some point the more you get the more you get. If > we get enough of it we're permanent toast - fully burnt toast at that. > The oceans will boil off and the surface of the earth will likely end up > over 200 deg. C. Welcome to New Venus. And then the carbonates boil out of the rocks and the curtain comes down for the last time, and the last thing we hear is the voice of a fundy saying "We *told* you it was the end times, and this proves we were right!" But it's very unlikely. If that was that easy to achieve it would have happened already. Here's why: Check out the "snowball Earth" era(s) which occurred in the past. Glaciation was extreme, reaching all the way -- or nearly all the way -- to the Equator. The Earth's albedo went sky-high, as a result of which the "effective insolation" rate plummeted -- runaway cooling. Why, you may ask, do we no longer have a snowball Earth? What finally stopped the "runaway"? Apparently what ended it was volcanism coupled with the fact that plant life on Earth was basically dead or dormant. Little CO2 was being pulled from the atmosphere by the plants, but volcanoes went right on pumping the stuff out. The result was massive CO2 accumulation in the atmosphere. Finally the greenhouse effect grew strong enough to melt the snowball, despite the high albedo. But to get to that point the CO2 level had to go sky-high -- many times higher than the "baseline value", and far, far higher than it is now. But when the ice melted and the albedo dropped again, all that CO2 was still in the atmosphere, and the result was massive overshoot: Toasted Earth. If we were ever in danger of turning into Nouveau Venus, that was the moment! But even that huge overshoot didn't go high enough to boil the oceans and cook the rocks. And as it seems unlikely we'll be able to get anywhere near such a big "bang" out of our current activities, if only because we're running out of oil which will force us to cut the CO2 emission rate, it also seems very unlikely we'll get to the "Venus point" before the temperature levels off. Anyhow that's my impression; take it or leave it. I can't provide references, since this is gleaned from snippets from assorted sources over a number of years, along with a few lunch-time talks with someone who has followed this a lot more closely than I have.
