A bit of a whimsical question, or a few questions really.
What would happen in a world with no air - no oxygen (plant life stop producing oxygen).
Specifically, let's say the oceans shut down oxygen production due to [insert reason here]. For that matter, what could cause the oceans to do this? I think I read that global warming would effect algae production, and overheated oceans aren't good for most life.
Then let's say someone manufactured a nanovirus that affected all plant life, removing their ability to create oxygen, while keeping their lives intact (absorbing carbon or some other evolution). Some sort of mutated photosynthesis where only half the equation was in place.
How long would it take before we ran out of air? Would fires greatly affect this, or would they not be able to burn? Would people suffocate, or just slowly blackout? What kind of timelines are we looking at - how long before the 7 billion people on the planet (plus animals) ran out of air/sufficient oxygen? Would humans be able to manufacture their own oxygen (I know they could, but at what levels)?
What kind of differences in timelines would there be if the ocean remained suitable but all land-based plants stopped producing oxygen?