How lowly bacteria froze Earth solid

[Dover]

How lowly bacteria froze Earth solid
Scenarios that led to snowball episode could happen again, scientists warn

By Robert Roy Britt
LiveScience
Updated: 3:03 p.m. ET Aug. 1, 2005


Earth has been through many cold spells since its birth 4.5 billion years ago. Scientists say some drastic episodes froze the planet all the way to the equator.

Yet these "snowball Earth" scenarios expose a gaping lack of understanding: What caused them?

Lowly bacteria, according to a new study.

In the first and worst snowball episode, 2.3 billion years ago, bacteria suddenly developed the ability to break down water and release oxygen. The influx of oxygen destroyed methane in the atmosphere, which had acted as a blanket to keep the planet warm.

The idea is presented in the latest issue of the Proceedings of the National Academy of Sciences by researchers at Caltech.

In modeling the scenario, the scientists say Earth's exact position from the Sun is the only thing that saved the planet from a permanent deep-freeze.

And, they caution, it could happen again.

http://msnbc.msn.com/id/8789252/

[Spinzonner]

1. Holy Cow

let's hope

[RobertSeattle]

2. Discovery Channel's "Miracle Planet" had a show on it too

(I missed it, but will look for the repeat)

Snowball Earth: First Complex Life
World Premiere
July 25, 2005 at 10 p.m. ET/PT
The hypothesis "Snowball Earth" explains that ice ages, caused by the earliest life-forms, resulted in an evolutional leap — larger-sized life. Atmospheric methane created by microbes initially kept the Earth warm. As microbes that produce oxygen (photosynthesizers) emerged, atmospheric methane was lowered. As a result Earth cooled and the primeval ocean froze to 1,000 meters deep.

Most life may have become extinct during a long period of intense glaciation believed to have lasted several million years. However, some life survived, perhaps in puddles created near volcanic craters. Carbon dioxide accumulated in the air because thick ice sheets prevented ocean water from absorbing it. A green-house effect, created by carbon dioxide, finally melted the ice and fed photosynthesizers.

Hyper hurricanes raged after the great meltdown and stirred up the ocean water, creating an ideal condition for life to prosper and develop collagen. Using collagen, life-forms were able to build larger bodies, and a variety of creatures, called Ediacara biota, emerged for the first time.

[n2doc]

3. And bacteria were responsible for keeping the earth warm before that

And responsible for getting the Earth out of "Snowball" condition. One thing that drives me crazy is the usual "could happen again" crap. No, it can't. As noted near the bottom, the sun is considerably brighter than it was 2.3 billion years ago. To get the world to go "snowball" one would have to remove most of the atmospheric CO2. And we ain't headed in that direction, unfortunately. Even during the ice ages, the coldest the Earth has gotten in the past 100 million years, CO2 was roughly half of today's values....