microbes breathing in ice

smerral · 2005-03-01 10:22:41

I came across this article on another forum and thought the folks here might find it interesting:

http://news.bbc.co.uk/2/hi/science/natu … 287579.stm

John Creighton · 2005-03-01 15:03:40

I found the article very interesting. I am curious if the bacteria are a net CO2 produce what do they feed on? Is there perhaps also photosynthesizing organisms that live in the ice?

Shaun Barrett · 2005-03-01 17:22:13

I found it interesting that the production of methane gas is feared most as the permafrost melts in any hypothesized future global warming.
Methane is a very powerful greenhouse gas and it terrifies global warming 'enthusiasts', who worry that a combination of rising CO2 and a 'methane spike' could trigger positive feedback mechanisms leading to runaway warming of the planet.
(For what it's worth, I personally don't worry so much about runaway warming because I feel Earth must have a system of strong checks and balances to counter such threats or it would have succumbed to Venus-like conditions long ago.)

But I wonder about Mars in this context.
Scientists speculate that Mars was once warmer and wetter in the distant past but they have trouble explaining how this might have been possible. Even if Mars had a 5-bar CO2 atmosphere, apparently there are theoretical difficulties in keeping the surface temperature above zero - especially since the Sun's output back then was only about 70% of today's.
But, what if methanogenic bacteria evolved quickly on early Mars and produced large quantities of methane as waste? Is it conceivable they may have produced enough methane to maintain a powerful greenhouse effect? ???

But then, even if such methanogens did exist and did keep Mars warm, it begs the question 'what happened?' Why isn't Mars still warm and wet?
I suppose it comes back to the twin problems of a failing magnetosphere and the stripping away of the bulk of the atmosphere due to the low gravity and the effects of 'sputtering' by the Solar Wind. Perhaps even an atmosphere with a high percentage of methane can only do so much to maintain a planet's warmth if the total atmospheric density falls below a certain 'tipping point'.

I suppose also (even more wild speculation on my part! ) it's not impossible that the warmth created by the methanogens allowed the evolution of other life-forms which out-competed the methanogens, bringing about a major reduction in their numbers.
The same thing happened here on Earth, where the planet-dominating cyanobacteria gradually produced an oxidizing atmosphere, which resulted in a 'blooming' of other life-forms and the end of their own dominance. They've since been reduced to relative 'also-rans', eking out a living in certain small inconspicuous niches like Shark Bay in Western Australia.
Unfortunately on Mars, any similar reduction in methane-producing bacteria would have proved fatal to the vital greenhouse effect, since Mars' insolation is only 43% of Earth's and the atmosphere was thinning. I can imagine a situation, maybe 3 billion years ago, where a flourishing biosphere was rapidly destroyed as conditions quickly deteriorated and the remaining atmosphere 'collapsed' into the regolith or froze out at the Poles.

The methane detected on Mars today might be coming from surviving populations of the original methanogens living in the warmer wetter parts of the regolith, especially deeper underground. If so, what a ride they must have had! They may have been the first form of life, witnessed multicellular complex life evolve around them, only to die off quickly, and now they're the only viable life-form once more.
Wow!! :laugh: (What a fevered imagination! )

Just a few thoughts.

Dook · 2005-03-01 18:21:56

How do we know for sure that the methane is produced by extant organisms? It could just be left over from whenever the last living organisms died out. If we could measure the amount of methane over time and see if it changes that would be a clue. Also wouldn't it fluctuate with the seasons? More in summer, maybe less in winter.

How likely is it that the methane was created by non-biologic processes?

Shaun Barrett · 2005-03-01 18:53:14

Dook:-

How do we know for sure that the methane is produced by extant organisms?

We don't. As an alternative, the methane has been put down to geothermal activity and even to the remnant of a volatile-rich comet which may have impacted on Mars some time ago.

It could just be left over from whenever the last living organisms died out.

There are constraints on this. Apparently, methane only lasts for 3 or 4 hundred years in the Martian atmosphere before it's broken down. I suppose if you postulate that the last living organisms died very recently indeed, then yes, you could be right. But it doesn't seem very likely that, out of billions of years of history, we should arrive with our sensors just in time to witness the fading breath of the last Martian bacteria.

How likely is it that the methane was created by non-biologic processes?

I think it depends which articles you read. I've seen some which indicate life is the most likely source of the methane.
But then, the fact is we don't know for sure yet and so all possibilities are still on the table.

I happen to think Mars harbours life - in fact, I'd find it remarkable if Mars didn't have at least bacterial life. But this is only by a process of deduction on my part; I'm happy with my own conclusion but that's just me.

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#1 2005-03-01 10:22:41

Re: microbes breathing in ice

#2 2005-03-01 15:03:40

Re: microbes breathing in ice

#3 2005-03-01 17:22:13

Re: microbes breathing in ice

#4 2005-03-01 18:21:56

Re: microbes breathing in ice

#5 2005-03-01 18:53:14

Re: microbes breathing in ice

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