thaluikhain said:
"f Earth suddenly lost its sources of oxygen replenishment, it would not take long for all the oxygen in the atmosphere to be depleted"
How long is long in this context?
firstly, the oxygen/carbon cycle is exactly that, it's not an input output relationship there are checks and balances in nature that prevent things like this occurring namely that if the CO2 in the atmosphere suddenly rose, plants, plankton, and other photosynthesising organisms would go into an extremely active state and suddenly use up allot of CO2 resulting in a rubber banding effect that slows carbon user's growth, emits oxygen and then slows down..
however, let's remove ALL the oxygen recycling and producing from the equation.
the atmosphere weighs roughly 6 quadrillion tons*
if approximately 20% of that is oxygen ( allowing a wide margin for error )
Tons of oxygen:
6,000,000,000,000,000 / 5 = 1,200,000,000,000,000
Earth area:
790,854,451,200,000,000,000,000 square inches.
Sea:
70% of the planet area, replenishes 80% of our oxygen.
Rainforest:
6% of the planet area, replenishes 20% of our oxygen.
replenishment/inch:
*1 100 ft tree = 6,000 pounds of oxygen/year
rather vague, but assuming 18" model tree has a leafy diameter of 4m
so, 790,854,451,200,000,000,000,000 x6% = 47451267072000000000000 square inches of rainforest.
let's make that more useful.
take one tree, assuming 4m diameter, area = pi x r^2
gives: 12.566370614359173x100 ( cm2 ) 1256.6370614359173
cm / inches = 0.393700787
1256.6370614359173 x 0.393700787 = 494.7390000606879910769151 Sq inches.
let's solve for the number of trees in the world, shall we?
6% of the world's area, 47451267072000000000000 / 1 tree, 494.7390000606879910769151
95,911,717,220,957,536,319.398561066025714566371175 total trees. ( ok, not 'really, really' but it's kinda fun. )
Rounding up, I have my reasons.
96,000,000,000,000,000,000 trees x 6000 Lb oxygen /year
Trees give us : 576,000,000,000,000,000,000,000 lb/o2/yr
/2000 ( tons )
288,000,000,000,000,000,000 tons/yr.
assuming the factoids about the rainforests and sea plankton are true, we know this is 20% of the earth's total oxygen production, so solving for the rest is simple ( 20%x5=100% )
288,000,000,000,000,000,000 x 5 = 1,440,000,000,000,000,000,000 tons
which leads us to a rather disturbing fact, that at any moment in time we only have:
6,000,000,000,000,000 tons of oxygen, but use 1,440,000,000,000,000,000,000 tons of oxygen per year, meaning we recycle it EXTEREMLY fast.
1,440,000,000,000,000,000,000 / 6,000,000,000,000,000 = 240000 times per year, 666.6666666666666667 times per day
( in fact, think about how often you breathe.. every living thing is doing this? and it actually makes sense.... )
it must, overall be in perfect balance or we would spiral out of control one way or the other quite rapidly.
Assuming that the carbon cycle is entirely stable, ( that production and usage are exactly equal ) and the figures i pulled from google searches are correct, ( and these are large assumptions!! )
crazy? perhaps.. true? well that's what the math says... 'shrug'
so, in conclusion:
we would be dead in no time flat if the oxygen cycle shut down overnight.
for the lols: 1440 minutes/day /600 ( oxygen swaps/day rate ) = 2.4 minuites.
bizarrely, that's about how long it would take to suffocate yourself in a plastic bag.
all tons are us 'short tons' = 2000lb.
* tree Source:
http://chemistry.about.com/b/2011/04/26/how-much-oxygen-does-one-tree-produce.htm
* oxygen Source:
http://www.topix.com/forum/news/global-warming/TQ7TLPU9UQRJE5AVC