The human body has been fine-tuned over millions of years of evolution. Like all living things, our species adapted to the environment. Those changes to human physiology usually occurred over what might seem to modern people as an impossibly long timespan.
But human chemistry, it seems, is now changing relatively rapidly, with potentially dangerous consequences for health.
The problem is that increased carbon dioxide in the air is altering human blood. Atmospheric CO2 now sits at about 420 parts per million and rising.
Ice core data shows this is the highest level in the last 800,000 years. Over eons of human evolution, CO2 levels were closer to 280 parts per million.
A new analysis by Australian scientists shows that the hike has raised average blood bicarbonate levels by 7% as we breathe in all the extra carbon dioxide. That is matched by lower levels of calcium and phosphorus.
Researchers obtained their data from the U.S. National Health and Nutrition Examination Survey, covering about 7,000 participants who underwent lab tests from 1999 to 2020.
These electrolytes help regulate blood acidity. High bicarbonate levels can lead to kidney problems, cardiovascular strain and impaired cellular function. Low calcium can cause abnormal heart rhythms and bone loss, while low phosphorus interferes with energy metabolism.
The levels measured today are still safe. But researchers estimate that they could begin to adversely affect human health by the end of the century unless steps are taken to reduce carbon dioxide levels.
And that, they say, makes the need for more research urgent.
The evidence is in every breath you take.