Geoloblog

Environmental science, traveling, and the sociology of the unraveling American dream.

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If you're looking for more about me, I'm pretty much hanging out over at my livejournal these days. I use this account for commenting on other people's blogs.

Monday, May 31, 2004

The Big Snowball in Space

Long piece crossposted from a discussion on Hatrack, where someone asked about the "science" of The Day After Tomorrow, specifically in reference to the fact that global warming was leading to cooler temperatures.

My personal favorite for global warming arguments is the comparison to the Paleocene Thermal Maximum, when a methane release from methane hydrates bumped the temperatures up considerably. It's the best paleo-analogue for the present experiment (what many earth science people call the fact that we've, you know, like tripled our atmospheric carbon dioxide).

If you want interesting ideas from an ice covered planet, don't just limit yourself to the glacial periods we've been going through for the last 2.5 million years. Go for the whole hog, back in the Proterozoic and the Neoproterozoic: the Snowball Earth. Basically, once ice covers a certain fraction of the globe, an unstable feedback is introduced, with more light reflecting off the lower-albedo snow, and the entire Earth's surface, land and snow, freezes over. Carbon dioxide then builds up over millions of years-- carbon dioxide is being emitted by volcanoes, but it isn't being deposited because the water cycle's gone-- and you get a severe greenhouse that blasts you out of the snowball in a very short period of time. More information on the snowball here (technical) and here (less technical).

(x-posted from a post I wrote at Hatrack River.)