CO2 dissolving in water might help remove the CO2 from the atmosphere, but then where did all the Earth's nitrogen go? There's a huge amount of nitrogen in the atmosphere of Venus that was presumably also in the early atmosphere of the Earth. I suppose the early Earth oceans could have been concentrated nitric acid, but the nitrogen would have at some point ended up in some form of nitrates & nitrites, which are highly soluble. Is there enough vegetation on the Earth to have absorbed all that nitrogen? I don't recall coal & oil deposits having large amounts of nitrogen in them, so the nitrogen from plant materials would have washed out & ended up somewhere else. At 09:20 AM 3/9/2011, Joshua Zucker wrote:

I always thought the explanation for the difference between Venus and Earth is that we never got hot enough to vaporize the oceans, and so the CO2 released by volcanoes and so on gets dissolved in water and ultimately ends up carbonate rock (limestone, etc) on Earth while it ends up atmosphere on Venus. Mars has little atmosphere partly because of the lower gravity but mostly because it's not so volcanically active.

In other words, vulcanism and oceans are the dominant processes. Losses to space are much slower.

But I'm far from expert on these issues so I'd love to learn more!

--Joshua Zucker

On Tue, Mar 8, 2011 at 9:17 AM, Henry Baker <hbaker1@pipeline.com> wrote:

...

Several years ago on math-fun, we had a spirited discussion about the possibility of smoke-stacks tall enough to reach orbit -- a la space elevators. During this discussion, I came to the conclusion that the Earth's atmosphere was far from equilibrium -- i.e., the Earth's current atmosphere is far too thin to have outgassed into space during its lifetime. Proof: Venus, which has a far denser atmosphere & due to its closeness to the Sun, should have outgassed much more of its atmosphere during this time than the Earth.