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I haven't seen any talk about the health effects of rising CO2. I know there are studies finding a difference in productivity between 600 and 1000 ppm with jus

I haven't seen any talk about the health effects of rising CO2. I know there are studies finding a difference in productivity between 600 and 1000 ppm with just hours of exposure, so isn't it possible that going from 300 globally to over 400 has had some health impact over a lifetime? Is there a point where lower CO2 has no effect and how do we know that?

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hartator 9y ago
The funny thing O2 is dropping faster than CO2 is rising, but for whatever reasons it's not really a subject of interest.
- mchannon 9y ago
  That's because it's easily explained. About half the O2 lost through burning of hydrocarbons becomes CO2. Other half becomes H2O. The latter doesn't increase its percentage in the atmosphere just because there's more of it.
  - hartator 9y ago
    Yeah, but my point is that lack of O2 is very easy to explain why it's bad of the health!
    - mchannon 9y ago
      Silly point. O2 shortages are irrelevant- 210,000ppm to 209,800ppm O2 is far less of concern than 300ppm to 400ppm CO2.
      - mikeash 9y ago
        And keep in mind that atmospheric pressure (and thus the partial pressure of oxygen) routinely varies by 10% or more due to weather, and people live at altitudes where the pressure is as low as 50% below sea level.
- deleted 9y ago
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gizmo686 9y ago
I doubt that increased atmospheric CO2 concentration is going to be a direct threat to human health. Humans have for a fair amount of time at this point, spent most of our time (and decision making time) indoors, where CO2 concentration grows far higher than atmospheric. In fact, reaching the 1000s ppm is already fairly common, and does not seem to have lead to major obvious health problems (although it does, as you identify, lead to short term cognitive decline). The bigger problem is that in our quest for energy efficiency, we would further reduce ventilation, increasing the indoor CO2 concentration; but this can be countered with better ventilation (using a thermal exchange system so it is more energy efficient than opening a window). The reduction of indoor CO2 possible from this is probably greater in most places than the ~100ppm increase in background concentration.

deleted 9y ago

[deleted]

hartator 9y ago

The funny thing O2 is dropping faster than CO2 is rising, but for whatever reasons it's not really a subject of interest.

mchannon 9y ago
That's because it's easily explained. About half the O2 lost through burning of hydrocarbons becomes CO2. Other half becomes H2O. The latter doesn't increase its percentage in the atmosphere just because there's more of it.
- hartator 9y ago
  Yeah, but my point is that lack of O2 is very easy to explain why it's bad of the health!
  - mchannon 9y ago
    Silly point. O2 shortages are irrelevant- 210,000ppm to 209,800ppm O2 is far less of concern than 300ppm to 400ppm CO2.
    - mikeash 9y ago
      And keep in mind that atmospheric pressure (and thus the partial pressure of oxygen) routinely varies by 10% or more due to weather, and people live at altitudes where the pressure is as low as 50% below sea level.
deleted 9y ago
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gizmo686 9y ago

I doubt that increased atmospheric CO2 concentration is going to be a direct threat to human health. Humans have for a fair amount of time at this point, spent most of our time (and decision making time) indoors, where CO2 concentration grows far higher than atmospheric. In fact, reaching the 1000s ppm is already fairly common, and does not seem to have lead to major obvious health problems (although it does, as you identify, lead to short term cognitive decline). The bigger problem is that in our quest for energy efficiency, we would further reduce ventilation, increasing the indoor CO2 concentration; but this can be countered with better ventilation (using a thermal exchange system so it is more energy efficient than opening a window). The reduction of indoor CO2 possible from this is probably greater in most places than the ~100ppm increase in background concentration.