[neilep (OP)]

Greetings,

How are ewe today ?..I'm Ok..I had an ECG earlier..I'll post it later !

The atmosphere of the Earth is my all time favourite gassy blankety thing that surrounds us and enables us to breath and stuff !

look, here it is .

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nice eh ?

say all life on the planet died...absolutely everything !!.....would the atmosphere survive ?..what would happen to it ?..would it eventually evaporate away. Could a passing astrosheep drop by in ten thousand years and still breathe in the airy goodness ?


whajafink ?

Hugs & shmishes


mwah mwah

neil
Atmosphere dwelling sheep
xxxxxxxxxxxxxxxxxxxxxxxx

[RD]

Without life (plants producing oxygen) Earth's atmosphere would become like that of Mars...
 

In early 1961, Lovelock was engaged by NASA to develop sensitive instruments for the analysis of extraterrestrial atmospheres and planetary surfaces. The Viking program that visited Mars in the late-1970s was motivated in part to determining whether Mars supported life, and many of the sensors and experiments that were ultimately deployed aimed to resolve this issue. During work on a precursor of this program, Lovelock became interested in the composition of the Martian atmosphere, reasoning that many life forms on Mars would be obliged to make use of it (and, thus, alter it). However, the atmosphere was found to be in a stable condition close to its chemical equilibrium, with very little oxygen, methane, or hydrogen, but with an overwhelming abundance of carbon dioxide. To Lovelock, the stark contrast between the Martian atmosphere and chemically-dynamic mixture of that of our Earth's biosphere was strongly indicative of the absence of life on the planet.

http://en.wikipedia.org/wiki/James_Lovelock

[neilep (OP)]

Thanks RD.

That's a fascinating link.

I can imagine then that the life on Earth must play a part in the Gaia hypothesis then.

so, would the atmosphere just evaporate away then ?

...hmmmm...surely a rudimentary atmosphere was around for the first life to live !..how did that happen ?

[RD]

would the atmosphere just evaporate away then ?

If all plants died no more oxygen would be added to the atmosphere.

The existing oxygen would slowly be removed from the atmosphere by oxidation, (e.g. Mars is covered in rust: iron oxide).

Even without any life present carbon dioxide would still continue to be added to Earth's atmosphere by volcanism.

So without life Earth's atmosphere would eventually* become mostly CO₂ like Mars.

[* Although I guesstimate this would take tens of millions of years rather than tens of thousands]. 

...hmmmm...surely a rudimentary atmosphere was around for the first life to live !..how did that happen ?

The earliest forms of life on Earth did not use oxygen: to them O₂ was poisonous pollution ...
http://www.ucmp.berkeley.edu/precambrian/proterozoic.html

[LeeE]

I think Venus might be a better match than Mars.

[chris]

Mars is probably a bad example of an atmospheric correlate because a) there might be life there - recall the very "young" methane discovered emerging seasonally from certain hotspots on the planet's surface - and b) Mars has no magnetic field and hence is ravaged by the solar wind, which is why it is so dessicated today.

Interesting question though.

Chris