With in the increase in carbon dioxide emmissions, I was wondering...

[SWBTATTReg]

that since plants and the like use carbon dioxide (like we humans do w/ oxygen), and back 200 million years or so (I'm being approximate here in time spans, so I may be off) oxygen levels (% of) was much higher than the 21% or so then (and trees / ferns / etc. covered the entire globe).

With the increase in CO2 levels today, are we (1) seeing higher or more vigorous plant growth, and also in conjunction at the same time, slowly increasing levels of oxygen due to the increase in plant growth?

I was curious if anyone has done a study in the relationship between plant growth and oxygen/co2 levels.

Thanks!

[hatrack]

1. Lots out studies out there, some running 10 or 20 years

This is a really clumsy summary of complex results (out the door in a second), but:

While plant growth in some studies did speed up under higher CO2 conditions, the growth spurts generally didn't last that long. When growth was goosed by CO2 plants, trees and shrubs grew faster, but in doing so, tended to use up soil nutrients faster as well, so that initial growth spurts leveled off after a few years.

In addition, some of the studies showed an advantage to grasses under high-CO2 conditions, and a relative disadvantage to trees and woody plants, which could indicate substantial shifts in the makeup of forest and grass cover in given habitats, especially given higher fire incidence and intensity, changes in temperature, rises in tree lines and things like that. I think you'll find this grass vs. tree study (with links) among recent posts on this board.

[NickB79]

2. Also, water becomes a limiting factor

Rising temperatures dry out soils faster, meaning more risk of drought and reduced plant growth.

[SWBTATTReg]

3. Thanks so much. I'll start digging around for these articles you mentioned...

One thing about DU, is that just about everything is out here, or there is a resource/go to available, such as yourself. I've seen several documentaries on this cretaceous period of time where grasses do become dominant, e.g., in Australia when it dried out.

I know that the oceans are getting pretty well filled up w/ carbon dioxide (it's what I've heard) so what happens to the 'excess' CO2? It's like that formative period in early Earth's history where co2 was consumed by Stromatolites (I might have misspelled this) and they in turn released oxygen for hundreds of millions of years.

Now, they are algaes in the oceans, plant cover throughout the globe on land, in effect, life all over, so when CO2 levels get high again (as in the past), does it force genetic mutations in plant life (revert to old genes that took up the excess co2) as well as the higher oxygen levels forcing older genetic material to 'become active' again?

Pls. don't mind me, I'm just rambling on and on, to a fascinating topic. Thanks.