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View Full Version : Time for the Earth to freeze over



wd40
2012-Oct-27, 11:59 PM
The film "Sunshine" (2007) depicted a dying Sun endangering humanity.

Air freezes at 58K (-215C). If the Sun was suddenly extinguished, or its heat production dropped to zero or was prevented from reaching us, about how long would it take for the Earth's temperature to drop for it to become a frozen air-slush ball: is it a matter of weeks, years, millennia or aeons?

antoniseb
2012-Oct-28, 07:58 AM
The life forms living near the undersea volcanic smokers would be unperturbed for a aeons.

Paul Beardsley
2012-Oct-28, 09:19 AM
Stephen Baxter did an article on this a few years ago. As I recall, it was a couple of months.

Xibalba
2012-Oct-29, 12:54 PM
Photosynthetic life would die first, quickly followed by herbivorous animals and then carnivorous ones, if they survived the dramatic change in their life that is the end of the day-night cycle.

Life in the sea would extinguish slower, with phytoplankton dying first, with algae, then zooplankton and herbivorous fishes and other sea creatures, and finally all the meat eaters of the blue.

There would be a short-lived proliferation of detritivores, eating the amazingly great pile of dead bodies, both at the bottom of the seas and lakes, and on land.

The last survivors would probably be chemotrophic bacteria in hot ponds like in Yellowstone and near the hot spots at the bottom of the seas. I think they might really well survive as long as the Earth emits some heat through these hot spots.

Humans would die quickly, too, once they've eaten all their canned food and eventually eaten every animal they could and then each others. This could take years after the last animal on land is dead before the last human dies, but the fall of the civilization will happen way before that..

Then, the time it takes for the Earth to freeze over is depending on how much output its internal structure emits, and for how long it can emit it. I suspect that the graph will look like a slowly descending line, spanning billions of years.

Githyanki
2012-Oct-31, 07:16 PM
Wouldn't life around thermal-vents have problems too? If there's no sunshine, is the Earth warm enough to keep the oceans from freezing completely except for around thermal vents? Also, the O2 supply would be cut off and only non-oxygen using microbes would be left.

Xibalba
2012-Oct-31, 09:29 PM
Wouldn't life around thermal-vents have problems too? If there's no sunshine, is the Earth warm enough to keep the oceans from freezing completely except for around thermal vents? Also, the O2 supply would be cut off and only non-oxygen using microbes would be left.

Yes, that's what I said, or at least that's what I meant. The oxygen diffusion in deep water is really really slow, so organisms that live there either live with really few oxygen, swim higher to get their oxygen, or get their energy by other means than photosynthesis (chemotrophy). Those habitats and inhabitants might not notice what's going on until some time.