Re: Oxygen content of the atmosphere over the last 10,000 years

Michael S. Lorrey (
Sun, 01 Aug 1999 22:08:11 -0400

Arla Johnson wrote:
> There is much debate over the appropriate co2 content of the atmosphere.
> No one that I know of has ever questioned the impact of both human and
> natural activities on the world's OXYGEN supply. After all 6 billion or
> so can
> live in a primordial swamp with oodles of co2 but we haven't any
> personal
> oxygen generators handy if the Oxygen begins to drop off.
> I have occaisionally looked for comparisons of modern and ancient oxygen
> measurements but have come up empty.
> Anybody have an idea about where or who has good documentation of this?

The oxygen in the atmosphere has been relatively constant since the Cambrian explosion. It is not a greenhouse gas. Greenhouse effects are far more dependent on methane and propane levels in the atmosphere than in the carbon dioxide level. This is why, despite there being a three to four times higher level of CO2 today than at any other period we have data on, we are not roasting like hot cakes. There has been a widespread decrease in the population of ungulates in the world (i.e. cows, moose, etc.) and natural fossil fuel seeps have all but dissapeared due to industrial exploitation. Additionally, consider that the sun's flux levels have been increasing over the last 20 years as part of a natural cycle.

Mike Lorrey