August 2, 2005 5:15 PM PDT

Bacteria froze the Earth, researchers say

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Humans apparently aren't the first species to change the climate of the planet. Bacteria living 2.3 billion years ago could have plunged the planet into deep freeze, researchers at the California Institute of Technology claim in a new report.

Several graduate students, along with supervising professor Joe Kirschvink, have released a paper presenting their explanation of what caused "Snowball Earth," a periodic deep freeze of Earth's atmosphere that has been theorized for years. The Caltech team argues that 2.3 billion years ago, cyanobacteria, or blue-green algae, gained the ability to break down water, which in turn released a flood of oxygen into the atmosphere.

That oxygen reacted with the atmospheric methane, which insulated the Earth at the time, and broke it down. While the oxygen-methane reaction created the greenhouse gas carbon dioxide, the protective nature of the barrier cracked.

Temperatures plunged to minus 50 degrees Celsius, and ice at the equator grew to 1 mile thick. Although this process took several million years, substantial damage to the methane layer could have occurred in the first 100,000 years.

Life-forms only recovered after microorganisms, clinging then to thermal vents or living underground, evolved the ability to consume oxygen and turn it into carbon dioxide.

It was a close call to a planetary destruction," said professor Kirschvink, who oversaw the project, in a prepared statement. "If Earth had been a bit further from the sun, the temperature at the poles could have dropped enough to freeze the carbon dioxide into dry ice, robbing us of this greenhouse escape from Snowball Earth."

Carbon dioxide concentrations became so high over millions of years that the temperature soared to 50 degrees Celsius. As the solar system aged, Earth's mood swings became less extreme.

Scientists have known for a number of years that Earth plunged into one of its periodic ice ages 2.3 billion years ago, a change reflected in glacially formed rocks in Canada. The cause, however, has been the subject of debate. Many experts have said that cyanobacteria evolved to break down water between 3.8 billion and 2.7 billion years ago, too early to cause the deep freeze.

The Caltech team believes the answer lies in the movement of glaciers at the time around the middle latitudes of the planet, which in part is borne out by magnetic readings of the Canadian rocks. The glaciers scraped iron, phosphorous and other nutrients off existing rocks. These ran into the ocean and provided food for a massive algal bloom.

"We could still go into Snowball if we goof up the environment badly enough," Kirschvink said. "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. We could probably get out only by becoming a runaway greenhouse planet like Venus."

20 comments

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Politicizing the news
What a moronic and politically-charged subhead in the RSS
description of your story: "Who causes global warming? Single-
celled organisms--and not SUV drivers--may be the real culprit."
Nowhere were SUV drivers mentioned in the story, yet this bit of
calculated misrepresentation effectively absolves fossil fuel
gluttons from any responsibility for their mindless and destructive
consumption. In fact, the story blamed microbes for global
FREEZING, not warming! And I thought only Fox News was the
propaganda arm of the Bush administration.
Posted by GRobLewis (61 comments )
Reply Link Flag
Your bias is very apparent
It is apparent from your comment that only a story supporting the global warming myth, which predominates the headlines lately, would satidfy you.

The story did not go into the politics of global warming/cooling other than to mention SUVs once. Yet you, demonstarting your apparent agenda and political leaning, went on to attack the author of the article and FOX with nothing to back up your accusations.
Posted by adornoe (270 comments )
Link Flag
It's too bad that you can't read....
... but then it's obvious that you can't think either. Your ranting,
even if it were in any way correct, has nothing to do with the
article. Please get down off your soapbox and take time to
understand what's really being said

Yes, 'Snowball Earth' did occur. The microbe theory makes sense
(also explains the iron ore deposits caused as the free oxygen
first combined with the iron dissolved in sea water). Global
warming occurred later as the volcanos replenished the CO2 and
other gases before plant life had direct access to the
atmosphere. And now, CO2 and other gases are starting another
global warming, partly from the fossil fuel burning that you
condemn so severely.

I assume that you walk everywhere you go? .. and you don't own
cows? ... and you don't have any termites?... and that you don't
believe in methyl hydrate?
Posted by Earl Benser (4310 comments )
Link Flag
Actually,
Rereading your response makes me think that you were reading a
previous version of the article, and that, since your post, the article
was corrected .

If so, I withdraw my previous comments with apologies.

I'm not sure, however, about the rant against Fox.
Posted by Earl Benser (4310 comments )
Link Flag
What This Story Really Proves
What this story really proves is that the scientists really have no conclusive proof what caused global warming/cooling in the past and what may cause it in the future. So lest we all get caught up in solving the WRONG problem, the focus needs to shift. Jettison the global warming/cooling argument and just agree that the less impact we have on Earth's environment the better. And the quest to do this will lead to better, cleaner, more sustainable technology.
Posted by Stating (869 comments )
Reply Link Flag
Scientific progress
I think this article does indeed add evidence to the case that there's alot we don't know, but I don't think we should find that discouraging. It just means we're very slowly moving from an entirely qualitative study of global environmental effect to a more quantitative understanding. I find that exciting and encouraging, to know that while much is still a mystery, we are slowly converging on true understanding of how things work.
In the meantime, it may be safest not to meddle with our environment too much, but I find it encouraging that we are making progress.
Posted by CompEng (201 comments )
Link Flag
CNET is NOT Scientific America
If you keep this up you must change your name to the "CNET
Enquirer", or simply create an off-shoot to "report" this ... stuff.

Get back on track.
Posted by Thomas, David (1947 comments )
Reply Link Flag
i like it
be quiet, I like this stuff, its diff than the usual geek comp net stuff
Posted by Zakynthos (23 comments )
Link Flag
Fascinating
Fascinating, thanks for reporting this.
Posted by (7 comments )
Reply Link Flag
More cool stuff!
If you liked that then try here:

<a class="jive-link-external" href="http://www.newscientist.com/home.ns" target="_newWindow">http://www.newscientist.com/home.ns</a>

There is enough interesting stuff to keep you busy for days!
Posted by Mister C (423 comments )
Link Flag
cookbook for how to prep other planets for colonization?
I'm not quite sure what set off the round of political bickering--this article is a straightforward and knowledgeable report on a scientific theory which is related to filling in the evolutionary history of the planet rather than explaining current global warning. Given the evidence that exists for the severity of the problem brought on in the early climate the last scientist's comment was not gratuitous, not partisan, and springs reasonably from the evidence.

I found it interesting that this sequence of chemical change of methane may point the way to how some of the more promising potential colonization points in the solar system, such as the moons of mars, could be prepared for use by introducing bacteria to convert their methane atmospheres...
Posted by Razzl (1318 comments )
Reply Link Flag
Re: cookbook for how to prep other planets for colonization
It would be an interesting starting point for terraforming. But you
need water, presumably lots of it, and millions of years as well. We
might be able to find the water, but as for the millions of years,
that's kind of doubtful. We need a clean cheap source of energy
here first before we can go colonizing the stars.
Posted by Mystigo (183 comments )
Link Flag
The quantity of methane .....
.... on the moons of Mars wouldn't even begin to fill you Bic. And
it's not too likely that a earth bacteria could survive any farther
from the Sun, like at Jupiter or Saturn distances.
Posted by Earl Benser (4310 comments )
Link Flag
yup
hahaha
Posted by ramonck (9 comments )
Reply Link Flag
Can help solve Earth problems
While not "colonization of other planets", advanced space exploration can help improve life on Earth, through:

- Technological spinoffs.
- Solar power satellites.
- Moving polluting/dangerous things into space.
- Extraction of space resources (asteroidal metals, cometary methane).
- Probably some other stuff that I don't know about.
Posted by (84 comments )
Reply Link Flag
 

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