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Carbon dioxide in atmosphere and blood

While the percentage of carbon dioxide (CO2) in the atmosphere is small, 0.04%, it is a very important greenhouse gas, and the 43% increase in the level since pre-industrial times is substantial; if the amount of CO2 in your blood increased as much as the atmospheric CO2 has increased you'd have a serious health problem.

This page written 2016/04/11
Contact: email daveclarkecb@yahoo.com (David K. Clarke) – ©

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The technical bit

Normal blood CO2 levels (measured as bicarbonate) are 23-30mEq/L; atmospheric CO2 has gone from 280-400ppm in 200 years, an increase of 43%. A 43% increase in blood CO2 levels would take it to 33-43mEq/L; well outside of normal levels.
Most people have little understanding of statements such as "CO2 has increased from 280ppm to 400ppm since pre-indutrial times". It is hoped that saying instead...

"There is CO2 in the atmosphere and there is CO2 in everyone's blood. If the amount of CO2 in your blood increased by the same proportion as has the amount of CO2 in the atmosphere you would have a serious health problem"

it might make the importance of the change clearer.

Direct health effects of increased CO2 levels

There is evidence that raised CO2 levels, even when only slightly raised from the pre-industrial levels, can have adverse health effects. These effects seem to be related to the increase in the acidity of the blood resulting from increased disolved CO2. See the references below.


Wikipedia: Hypercapnia, excessive CO2 in blood

Climate Progress: Elevated CO2 Levels Directly Affect Human Cognition; by Joe Romm Oct 26, 2015.

The Climate Progress article refers to an article published in Environmental Health Perspectives: Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments; by Joseph G. Allen, Piers MacNaughton, Usha Satish, Suresh Santanam, Jose Vallarino1, and John D. Spengler.

Effect of high CO2 levels on humans

A proposed potential role for increasing atmospheric CO2 as a promoter of weight gain and obesity: by L-G Hersoug, A Sjodin, and A Astrup.