[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Mystery of Mass Extinctions Is No Longer Murky

Hi Guys

Having studied atmospheres a bit I concur - Earth can't get so hot that it wouldn't rain anymore. I'm not entirely sure the Earth would even be dehydrated the same way Venus is supposed to have lost its ocean. Hydrodynamic outflow of gases from Venus' exosphere in the early days of the Solar System was driven partly by the much higher UV put out by the early Sun.

However a "wet Greenhouse" is hotter than a high-pressure autoclave, even if the oceans are still around - with about 10 bars worth in the atmosphere. Could Earth be tipped towards that end-state? We really don't know, but the end of the Cryogenian glaciations via a massive greenhouse was the worst seen since the hot times of the Archean - and the Earth didn't tip then. Would our little perturbation really be enough to push the Earth's systems past that point? Maybe not, but it could end up with 50 C temperatures in the Caribbean like during the Cretaceous...


David Marjanovic wrote:

I don't understand why some people insist that a mass extinction cannot possibly have a single cause. Sure everything tends to turn out to be more complicated than we thought at first, but why start with the maximally munificent hypothesis?

----- Original Message -----
From: "don ohmes" <d_ohmes@yahoo.com>
Sent: Wednesday, July 02, 2008 5:17 PM

If: [...]
2) our current climate system is such that a "run-away" greenhouse can occur.

If by "runaway" you actually mean "runaway", as on Venus, then it isn't. There is no chance that it could get so hot it doesn't rain anymore.

But a sea-level rise of a single meter, let alone three, is bad enough. We're talking about hundreds of millions of people having to move. Even if spread through decades, that's horror enough. And I haven't even mentioned the golden toad yet.