Wouldnt it be a really really long time to run out of oxygen?
“What would happen if we combusted every living cell on Earth?” it asked. That is, Peters wanted to know what would happen to the atmosphere if you burned down not just the Amazon, but every forest on Earth, every blade of grass, every moss and lichen-spackled patch of rock, all the flowers and bees, all the orchids and hummingbirds, all the phytoplankton, zooplankton, whales, starfish, bacteria, giraffes, hyraxes, coatimundis, oarfish, albatrosses, mushrooms, placozoans—all of it, besides the humans.
Peters pulled up the next slide. After this unthinkable planetary immolation, the concentration of oxygen in the atmosphere dropped from 20.9 percent to 20.4 percent. CO2 rose from 400 parts per million to 900—less, even, than it does in the worst-case scenarios for fossil-fuel emissions by 2100. By burning every living thing on Earth.
https://www.theatlantic.com/science/archive/2019/08/amazon-f...