Atmospheric Degredation

[Red Dwarf]

If all the plants on Earth stopped producing oxygen, how long would it take before the atmosphere became unbreathable?

[lajoswinkler]

Do you mean all true plants or every photosynthetic organism?

[Galacticruler]

Do you mean all true plants or every photosynthetic organism?

This. Be specific Red, there are things that make 02 other than plants.

[7499275]

He only said plants so just go with that unless we hear back? I'm kinda curious about this too. I know it wouldn't be long thanks to the rate at which humans pump out CO2

[Red Dwarf]

I probably should have specified that... Yes, I meant all oxygen-producing organisms. I thought plants were all of it, but thinking about it, plankton does it too, as well as some others.

[Z-Man]

Would they still magically be alive and edible? Because if not, all animals would easily starve way before carbon dioxide poisoning (let alone oxygen deprivation) becomes a problem, and then only geological processes are left to influence the atmosphere.

[Red Dwarf]

I guess so. In the story I'm writing, the plants and other oxygen-making lifeforms are infected with a virus, which stops them producing breathable air. They're still there, but they aren't doing anything. It is probable that animals would starve, but that isn't really my question. I care more about the atmosphere itself.

[Z-Man]

Humans are animals, too. With a slightly better food supply management, granted, but they would still all starve before they suffocate. Basic estimate: Imagine you burn all organic material, calculate how much CO2 that is going to release. It's not enough to get to toxic levels. And no matter what you do, no biological process would be able to release more CO2.

If you want suffocation to be a risk, have your virus "reverse" photosynthesis so it extracts oxygen from the air somehow (and faster than animals would do it) or modify it so that all plants now produce a more toxic waste product, like cyanide acid. Or just pick a number and apply suspension of disbelief.

[lajoswinkler]

Most of the heterotrophs would starve long before the level of oxygen drops down below tolerable physiological levels for any of them. It would probably take a few thousands of years before oxygen is reduced into compounds. After that, life would go on for anaerobic bacteria and their parasitic viruses.

[Red Dwarf]

Thousands of years, huh? I guess I can make that work. Actually, it might make the narrative more interesting. Sins Of Our Forefathers, kind of thing.

[N_las]

You can't stop the metabolism of plants and still expect them to life. If plants stop "producing" oxygen, that means they stoped growing. They will die and all animals and humans will starve.

[Red Dwarf]

I know that Whether or not the plants are still alive or not doesn't matter. My question was more about how the planet itself would be affected by their absence. Everything dying is a foregone conclusion.

[Everten P.]

I don't think you understand what plants do red dwarf. Plants don't just produce oxygen for no good reason. Oxygen is a by-product of photosynthesis which produces sugar from a combination of carbon dioxide and chlorophyll, this sugar goes into a process called cellular respiration which converts sugar and water to ATP and carbon dioxide ATP is a cell's main source of energy animal or plant. So knowing this this means there is no way for a virus to make a plant produce unbreathable air before the plant dies and the oxygen to carbon dioxide ratio is high enough that there is more oxygen made than carbon dioxide. A better scenario would be if all plant life died and the fungus population skyrocket producing carbon dioxide while most species of animal a reduced to a strict fungi diet meaning that the humans and other animals would live long enough to experience oxygen deprivation and carbon dioxide poisoning. So what then?

Note: I was trying to refine his theory so that it would be more clear or flawless to figure out how long we would have.

P.S. Sorry for a whole science lesson.