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 by the same proportion as the atmospheric CO2 has increased you'd have a serious health problem.

This page written 2016/04/11, last edited 2021/02/15
Contact: David K. Clarke – ©



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 "atmospheric CO2 has increased from 280ppm to 400ppm since pre-industrial times". I hope 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 atmospheric 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 dissolved CO2. See the references below.

The increase in the acidity of the blood due to increased CO2 has a direct correlation to the increase in the acidity of the oceans due to the increase in atmospheric CO2.


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.

Donating plasma

While on the subject of blood...

Donating plasma at the Bendigo Blood Bank
Plasma donation
Only 3% of Australians donate blood or blood products. Donating blood is easy, painless, and takes little time.

You can donate whole blood every three months, plasma every two weeks.

If you can do some good, at very little trouble to yourself, why would you not? I have written elsewhere about compassion, contributing to your society and ethics. Another way that you can do some good anywhere you go is by picking up rubbish; there's no shortage of it on most roadsides and picnic areas.

And all of us should be doing everything we can to try to minimise climate change if we have any care for those who will come after us.

We all have a choice in what we try to do with our lives; many people decide that chasing money or power is what they should aim at, there are far better choices.