Scientific Question About Oxygen and Humans?

The concentration of oxygen in the atmosphere has changed both up and down over the last 3 billion years. Times of high carbon dioxide concentration are correlated with high atmospheric and ocean temperatures and low oxygen concentrations in both of them. As water temperature rises due to increased air temperature, the concentration of dissolved oxygen in the oceans goes down. Water dissolves less oxygen at higher temperatures. The rises in the atmospheric carbon dioxide, temperature and oxygen concentrations caused mass extinctions. The worst of these was the Permian-Triassic extinction 250 million years ago that killed an estimated 95% of all animal species.

During these extinctions, some species evolved respiratory systems that were very efficient at extracting oxygen from air where the concentration was low. Evidence indicates that dinosaurs had air sacs similar to modern birds which evolved from the dinosaurs. Birds evolved to live in low oxygen environments. The oxygen concentration could have been as low as 8%. Mammals (including humans), however, evolved to live in environments with higher concentrations such as the current 21%.

One very important point is that the some day might be a lot sooner than millions of years in the future. As we are altering our atmosphere and oceans, we are creating positive feedback cycles that may already be beyond control. The anthropogenic global warming of the air and water may lead to an extinction of humans and other species sooner than we used to think.

Well there is no such thing as indefinitely, first off. I think we would long die of diseases and poisons in the air that would result from a lack of oxygen supply, rather than actually suffocating.

probably not but im waiting for someone to create a machine that creates oxygen