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Earth atmosphere is 0.04% CO2. Why does Earth have such little CO2? Is maybe used by life on early Earth?

perl4ever 7y ago
Is that a rhetorical question? I assume it's something to do with: https://en.wikipedia.org/wiki/Limestone https://en.wikipedia.org/wiki/Limestone
rozab 7y ago
Yep. https://en.wikipedia.org/wiki/Great_Oxidation_Event https://en.wikipedia.org/wiki/Great_Oxidation_Event
mattkrause 7y ago
I’m pretty sure we still have plants, though I admittedly haven’t been out of the house much. A lot of carbon was also captured during the aptly-named Carboniferous Period 360-300 million years ago. Woody plants had just evolved, but microbes that could break them down had not. Thus, coal. An earlier drop in sea levels also caused carbonate (as in limestone, dolomite, and iron ores) to precipitate out. The combination of these effects pushed oxygen levels about 50% above present, allowing very large animals to evolve.
- saagarjha 7y ago
  > Woody plants had just evolved, but microbes that could break them down had not. Thus, coal. Does this mean we’ll never have coal again?
  - anticensor 7y ago
    We will, but the balance is much more against coal now. We will have it consumed before it is replaced.
  - mattkrause 7y ago
    It's not totally impossible for coal to still form, but the conditions are far, far less favorable: microbes get everywhere and the woody plants have a lot less lignin now than they used to, which also makes them easier to decompose. So, yeah, we're pretty got what we got. Interestingly, this has happened once before. There's a "coal gap" from about 250-230 million years ago during which little-to-no coal was formed in most places. I'm not sure if anyone is sure why; this is right at the time of the P-Tr extinction, so a lot was happening. One theory is that the ligninaceous plants went extinct or other conditions were much less conductive to coal formation. (FYI: Not a paleontologist or anything like--just a scientist who liked dinos as a kid and remembered some keywords!)
cryptonector 7y ago
Yes. Earth used to have a lot more CO2. Then photosynthesis in the oceans created an oxygen crisis.
- dredmorbius 7y ago
  And Global Cooling, as both methane and CO2 (both potent greenhouse gasses) were reduced out of the atmosphere. The resulting glaciation extended across the entire planet, was kilometers deep, and lasted 100s of millions of years. All because blue-green algae. https://en.wikipedia.org/wiki/Huronian_glaciation https://en.wikipedia.org/wiki/Huronian_glaciation
- chrisco255 7y ago
  "The cyanobacteria producing the oxygen caused the event which enabled the subsequent development of multicellular forms." Seems like it was ultimately a win.

Is that a rhetorical question? I assume it's something to do with: https://en.wikipedia.org/wiki/Limestone https://en.wikipedia.org/wiki/Limestone

rozab 7y ago

Yep. https://en.wikipedia.org/wiki/Great_Oxidation_Event https://en.wikipedia.org/wiki/Great_Oxidation_Event

mattkrause 7y ago

I’m pretty sure we still have plants, though I admittedly haven’t been out of the house much. A lot of carbon was also captured during the aptly-named Carboniferous Period 360-300 million years ago. Woody plants had just evolved, but microbes that could break them down had not. Thus, coal. An earlier drop in sea levels also caused carbonate (as in limestone, dolomite, and iron ores) to precipitate out. The combination of these effects pushed oxygen levels about 50% above present, allowing very large animals to evolve.

saagarjha 7y ago
> Woody plants had just evolved, but microbes that could break them down had not. Thus, coal. Does this mean we’ll never have coal again?
- anticensor 7y ago
  We will, but the balance is much more against coal now. We will have it consumed before it is replaced.
- mattkrause 7y ago
  It's not totally impossible for coal to still form, but the conditions are far, far less favorable: microbes get everywhere and the woody plants have a lot less lignin now than they used to, which also makes them easier to decompose. So, yeah, we're pretty got what we got. Interestingly, this has happened once before. There's a "coal gap" from about 250-230 million years ago during which little-to-no coal was formed in most places. I'm not sure if anyone is sure why; this is right at the time of the P-Tr extinction, so a lot was happening. One theory is that the ligninaceous plants went extinct or other conditions were much less conductive to coal formation. (FYI: Not a paleontologist or anything like--just a scientist who liked dinos as a kid and remembered some keywords!)

cryptonector 7y ago

Yes. Earth used to have a lot more CO2. Then photosynthesis in the oceans created an oxygen crisis.

dredmorbius 7y ago
And Global Cooling, as both methane and CO2 (both potent greenhouse gasses) were reduced out of the atmosphere. The resulting glaciation extended across the entire planet, was kilometers deep, and lasted 100s of millions of years. All because blue-green algae. https://en.wikipedia.org/wiki/Huronian_glaciation https://en.wikipedia.org/wiki/Huronian_glaciation
chrisco255 7y ago
"The cyanobacteria producing the oxygen caused the event which enabled the subsequent development of multicellular forms." Seems like it was ultimately a win.