The atmosphere of our planet has changed over geological time spans and I think it is worthwhile to reflect on what exactly that means for us and our future.
Carbon dioxide is released into the air through the process of combustion, burning of hydrocarbon fuels. When burnt, hydrocarbon fuels not only release carbon dioxide, they also release water vapor and consumes oxygen. We have increased the carbon dioxide content of the atmosphere from 280 parts per million to 367 parts per million. That’s an increase of 87 parts per million. We’ve decreased the oxygen content of the atmosphere also by 87 parts per million, because it takes one O2 molecule for every CO2 molecule produced through combustion.
Presently, the Earth’s atmosphere is approximately 78.1% nitrogen, 20.9% oxygen, .9% argon, .0367% carbon dioxide, and the balance is mostly water vapor. There are a number of trace elements, primarily other noble gases. Oxygen levels in the past have varied, but what I am learning is that there is no direct way known to measure ancient oxygen levels and depending on the method used estimates varied wildly. For example, on estimate had the oxygen levels as high as 35% 140 million years ago. The estimate was based upon insect size and other factors. Now another source estimates lower.
Primary factors that affected oxygen levels involved plate tectonics and sulfur. Exposing sulfur rich rocks in large amounts can rapidly deplete oxygen from the atmosphere.
Now, we’ve got a world hungry for energy, and burning hydrocarbons seems to be the method of choice for obtaining it. We really need to get away from this but there are many financial interests that would rather we stay the course. As a solution to CO2 emissions they suggest carbon sequestration, even though know proven technology has proven to be effective in the long term.
Carbon sequestration though also is oxygen sequestration because that CO2 taken and buried, took as much O2 out of the air in it’s formation. Folks, case you hadn’t noticed, human beings are somewhat dependent upon this oxygen atmosphere as is almost every other animal form on this planet, the only exceptions being some deep see worms near deep ocean thermal vents that have evolved the ability the use sulfur as an oxidizer rather than oxygen.