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When Microbes Ate the Ocean
museumpeace writes "When /. discussed a story about microbes that could break down water as a hydrogen source, many commentors went off on a tangent joking about runaway germs eating the oceans. Now, prof Joe Kirschvink and students at CalTech propose that indeed, the worst iceage ever, which nearly ended life on earth 2.3 billion years ago, was the result of algae evolving the ability to break down water and flooding the atmosphere with oxygen. The absence of oxygen consuming organisms at that time is said to have lead to destruction of atmospheric methane which had hitherto warmed the earth. The professor concludes: 'We haven't had a Snowball in the past 630 million years, and because the sun is warmer now it may be harder to get into the right condition. But if it ever happens, all life on Earth would likely be destroyed.'"
you would never beable to get out of the iceage again or something like that.
That conundrum was solved over 30 years ago. As glaciation reaches the equator and covers the oceans (not to mention all other forms of liquid water) precipitation drops to virtually zero - much like the conditions you see at Amundsen-Scott in Antarctica. That means that carbon dioxide, which is usually washed out of the atmosphere via rain, slowly accumulates over time. And I do mean slowly, since the primary form of input is through volcanic eruption.
In any event, there's eventually enough carbon dioxide in the air that sunlight reflecting from the ice gets trapped between the ice and the carbon dioxide layer in the atmosphere. This heats up the atmosphere, which starts to melt the ice, which means less sunlight is reflected from the ice and more is trapped in the atmosphere, which means things get hotter and more ice melts, etc. etc. Your snowball world begins to melt and things start swinging wildly towards the other end of the spectrum: a Venus-like hothouse.
What's to stop a runaway greenhouse effect? Well, with the ice melting and free water making a reappearance you once again get clouds. And that means rain. And that means that some of the carbon dioxide gets washed out of the atmosphere. The more ice that melts the more rain there is the more the carbon dioxide layer begins to fail.
Snowball Earths can't be sustained indefinitely, nor can greenhouse Earths, so long as there's active volcanism.
Max
My god carries a hammer. Your god died nailed to a tree. Any questions?
Wikipedia. Volcanoes. Easy to read about it.
Quote: "Volcanic activity now releases about 130 to 230 teragrams (145 million to 255 million short tons) of carbon dioxide each year."
Sometimes much higher if there is a extremely large eruption.