That's oxygen produced, not oxygen total. Dropping to 80% yearly production isn't going to remove the already stockpiled oxygen in the system, so how quickly we

That's oxygen produced, not oxygen total. Dropping to 80% yearly production isn't going to remove the already stockpiled oxygen in the system, so how quickly we notice is going to depend on how much oxygen is being "removed" from the system at the same time. From a different paper- > Oxygen concentrations are currently declining at roughly 19 per meg per year, or about 4 ppm per year. One "per meg" indicates one molecule out of 1,000,000 oxygen molecules, or roughly one molecule in 4.8 million molecules of air.