Discussion
The percentage of O2 in the atmosphere is about 20%, and IIRC has remained almost exactly the same since it was first worked out about 300 years ago.
In that time the world's population has ballooned, fossil fuels have been burned in stupendous amounts, and forests the size of countries have been destroyed. Yet despite the greater demand for O2 and less greenery to make it, the percentage remains the same. How does nature do that?
In that time the world's population has ballooned, fossil fuels have been burned in stupendous amounts, and forests the size of countries have been destroyed. Yet despite the greater demand for O2 and less greenery to make it, the percentage remains the same. How does nature do that?
Don't worry too much...... as we starting ramping up hydrogen production there will be a lot more oxygen pumped into the atmosphere...... then we will have the problem the earth will spontaneously combust through too much oxygen.... global warming on a massive scale through the unintended consequences of burning clean hydrogen rather than dirty oil.... 
ChocolateFrog said:
Are there not a few trillion trees in a northern belt around the siberian latitudes?
I also thought a significant proportion of oxygen is made by algae.
Scientists miscounted trees previously, easily done, and after a recount there are a few trillion trees in total...however, photosynthesising microstuffs in the oceans are small, but numbers matter.I also thought a significant proportion of oxygen is made by algae.
The Grauniad enlightens.
Oops look over there more trees
Edited by turbobloke on Saturday 29th April 11:01
Raccaccoonie said:
Billions of years to get to where we are, even humans couldn't destroy it in a few hundred years, maybe 1k years.
Drop in the ocean.Humans producing hydrogen for buses using abundant water will also produce oxygen - bets are it won't be released though, it's expensive/valuable, and as above, drops in the ocean make little difference. See 'orders of magnitude'.
If you compare the absolute amounts of O2 and CO2 in the atmosphere you can see why we can change the level of CO2 significantly without having any kind of impact on the levels of O2.
CO2 is about 0.03% of the air. O2 is about 20%. So you could double the amount of atmospheric CO2 and the level of O2 would still be about 20%.
CO2 is about 0.03% of the air. O2 is about 20%. So you could double the amount of atmospheric CO2 and the level of O2 would still be about 20%.
Edited by ATG on Saturday 29th April 11:13
Raccaccoonie said:
Out of everything stupid humans do I think plastics will be the world killer.
Hopefully the plastic situation will be addressed, a start has been made, though without more reckless over-enthusiastic banning of plastic as it's also extremely useful.Back to oxygen, and comparing it with carbon dioxide, where the level has increased recently from 300ppmv to 400ppmv, which means it's now at 0.04%
The human perturbation (interference) within the total of naturally cycled carbon dioxide is only 5% which is a small disturbance and not all output remains up there, even so that level rise is 0.01 percentage points.
Oxygen is fairly static at 21% which is 3 orders of magnitude greater than the carbon dioxide level, hence 'drop in the ocean'. Everyone is free to be concerned, but fwiw one view based on the above and what's happened / happening, is there's no need to be concerned about oxygen in the context being discussed.
One scenario would involve major, sustained, supervolcano activity. Not the occasional tiddler timetable. This would release a lot of sulphur dioxide which can react with oxygen. Personal view - not likely.
(ATG posted while typing, agreeing)
ATG said:
If you compare the absolute amounts of O2 and CO2 in the atmosphere you can see why we can change the level of CO2 significantly without having any kind of impact on the levels of O2.
CO2 is about 0.03% of the air. O2 is about 20%. So you could double the amount of atmospheric CO2 and the level of O2 would still be about 20%.
It wasn't a comment on CO2, I was just wondering how the O2 level manages to stay the same. I assumed nature was compensating somehow.CO2 is about 0.03% of the air. O2 is about 20%. So you could double the amount of atmospheric CO2 and the level of O2 would still be about 20%.
Simpo Two said:
ATG said:
If you compare the absolute amounts of O2 and CO2 in the atmosphere you can see why we can change the level of CO2 significantly without having any kind of impact on the levels of O2.
CO2 is about 0.03% of the air. O2 is about 20%. So you could double the amount of atmospheric CO2 and the level of O2 would still be about 20%.
It wasn't a comment on CO2, I was just wondering how the O2 level manages to stay the same. I assumed nature was compensating somehow.CO2 is about 0.03% of the air. O2 is about 20%. So you could double the amount of atmospheric CO2 and the level of O2 would still be about 20%.
Allegedly, the level has fallen by 0.7 percentage point over approx 1 million years ro the present. There are very small variations iirc e.g. seasonal.
Scripps have been measuring the ratio between atmospheric oxygen and nitrogen (expressed using similar notation to isotope ratios) which does show small changes over time (in the range of a few tens of molecules per million). Obviously the ratio can change with either nitrogen concentration or oxygen concentration or both.
Isotopologue said:
Scripps have been measuring the ratio between atmospheric oxygen and nitrogen (expressed using similar notation to isotope ratios) which does show small changes over time (in the range of a few tens of molecules per million). Obviously the ratio can change with either nitrogen concentration or oxygen concentration or both.
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