2
$\begingroup$

How much oxygen saturation have we lost in the last 100 years? As oxygen levels dwindle and industry, deforestation, and population increases, at what year and saturation will the low levels of oxygen become a problem in human development? Would living or sleeping with higher levels of oxygen increase cognitive or physical ability?

$\endgroup$
  • 1
    $\begingroup$ Athletes in aerobic sports, e.g., cycling, sometimes live and sleep at lower (rather than higher) levels of oxygen in order to increase their oxygen carrying capacity and improve their physical performance. Particularly high levels of oxygen are actually toxic over moderate time periods. I'm not sure either of these things are what you're getting at, though. $\endgroup$ – De Novo supports GoFundMonica Aug 8 '18 at 19:21
4
$\begingroup$

Good estimates from ice core samples put the decrease in oxygen concentration at 0.7% over the last 800,000 years. At sea level, currently, inspired $P_{O2}$ is (760 mm Hg - 47) * 0.21, approximately 150mm Hg. Human physiology easily adapts to lower $P_{O2}$ levels, with approximately 140 million people living at elevations over 2500 m, with inspired $P_{O2}$ at 108mm Hg, and many permanent human settlements higher than 5000 m, with inspired $P_{O2}$ approximately half what it is at sea level (see West Respiratory Physiology, Ch. 9). A 0.7% decline over 800,000 years isn't going to be much of a challenge.

$\endgroup$
  • $\begingroup$ That is before we had chain saws. I'm looking for more recent numbers and the effects on the human body.+1 for the info though. $\endgroup$ – Muze the good Troll. Aug 8 '18 at 19:03
  • 1
    $\begingroup$ @Muze the impact of industry is an increase in certain gases, not a significant decrease in oxygen. The gases that have increased substantially since the industrial revolution, e.g., $CO_2$, $O_3$, $CH_4$ are low percentage gases, but have a significant effect on the temperature of the earth through their interaction with radiant energy. There isn't a significant $O_2$ depleting impact. $\endgroup$ – De Novo supports GoFundMonica Aug 8 '18 at 19:09
  • $\begingroup$ So there is a decrease although insignificant. It takes 10 trees to provide enough oxygen for 1 person and if those trees are cut exponentially oxygen supply will also continue to fall. yes? $\endgroup$ – Muze the good Troll. Aug 8 '18 at 19:13
  • $\begingroup$ @Muze Deforestation causes a $CO_2$ problem, not an $O_2$ problem. As you can see from my answer, we have a large excess of $O_2$. $CO_2$, however, is a greenhouse gas, and small absolute increases (which are large relative increases) have significant effects on the biosphere. $\endgroup$ – De Novo supports GoFundMonica Aug 8 '18 at 19:20
  • 1
    $\begingroup$ @Muze Claims like It takes 10 trees to provide enough oxygen for 1 person would really need a reference. You will note that, if I am not mistaken, while forests are good carbon store, many forest ecosystems do no capture more CO$_2$ than they produce as they've reached their community climax and hence not carbon sink. I would think that such statistics (10 trees to provide enough oxygen for 1 person) hide a much more complex reality and can only be misleading. $\endgroup$ – Remi.b Aug 8 '18 at 21:36

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.