Will the atmosphere run out of CO2?

dav2008

I watched a program on some public broadcast channel where a professor from a university detailed the possible ends of the earth.

One of them (from what I recall) had to do with lowering CO2 levels in the distant future. The lack of CO2 would eventually kill off all plant life.

I tried searching the internet for a more detailed explanation but I couldn't find much as most searches turned up global warming pages. Does anybody know about the fate of Earth's atmosphere?

Astronuc

Based on the discussion of global warming these days, it would seem that there is an abundance of CO₂.

What is the argument for the loss of CO₂?

dav2008

That's what I'm wondering: what is the reason behind it?

Obviously in the short term CO2 levels are rising, however I am talking tens or hundreds of millions of years into the future.

russ_watters

Well didn't the program say why? Its a little hard for us to read the minds of the guys who wrote the show...

In any case, there is no reason I can think of why the earth would run out of CO2.

Andre

Yes there have been theories about that. My guess is that all the carbon would eventually would dissapear into the earth crust either as fossil remains of life (peat - coal) or as limestone due to chemical rock weathering.

Some of that carbon returns as magma heats up limestone and decomposes it into CaO and CO2 emitted by volcanoes but that's only a small part.

The only possiblitly to recycle the fossile carbon is human activity: mining and oil drilling.

So in the end those horrible oil companies are saving the world from becoming a barren lifeless desert.

Gonzolo

Don't Mars and Venus have plenty of CO2?

Phobos

Yes, the atmospheres of Venus & Mars are mostly comprised of CO2 (over 90% for both I think). Venus' atmosphere is incredibly thick whereas Mars' is very thin.

dav2008

The reason I'm posting here is because I don't remember why.

I thought it might be a common scenario that people know about. I'll see if I can catch the show again. I think they replay it once in a while.