Reply #21: Here are a few grains to help your digestion... [View All]

[petronius]

"As fossil fuels burn, they generate carbon dioxide, using up oxygen in the process," explains Mr Ray Langenfelds from CSIRO Atmospheric Research. "About half of the carbon dioxide from fossil fuels remains in the atmosphere."

"The changes we are measuring represent just a tiny fraction of the total amount of oxygen in our air (20.95 per cent by volume). The oxygen reduction is just 0.03 per cent in the past 20 years..."

http://www.sciencedaily.com/releases/1999/07/990719033405.htm


Many good reasons exist for placing deforestation near the top of our list of environmental sins, but fortunately the fate of the Earth's O2 supply does not hang in the balance. Simply put, our atmosphere is endowed with such an enormous reserve of this gas that even if we were to burn all our fossil fuel reserves, all our trees, and all the organic matter stored in soils, we would use up only a few percent of the available O2. No matter how foolishly we treat our environmental heritage, we simply don't have the capacity to put more than a small dent in our O2 supply.

While no danger exists that our O2 reserve will be depleted, nevertheless the O2 content of our atmosphere is slowly declining--so slowly that a sufficiently accurate technique to measure this change wasn't developed until the late 1980s. Ralph Keeling, its developer, showed that between 1989 and 1994 the O2 content of the atmosphere decreased at an average annual rate of 2 parts per million. Considering that the atmosphere contains 210,000 parts per million, one can see why this measurement proved so difficult.

http://www.columbia.edu/cu/21stC/issue-2.1/broecker.htm

As for that 38% claim, this article has a rather generalized figure of O₂ concentrations over millions of years - there is no spike at the end of the record...