Could rising CO2 levels be silently altering our blood chemistry? A new study suggests that the answer is yes, and the implications are both fascinating and concerning. But here's where it gets controversial...
For decades, scientists have been monitoring the Earth's rising carbon dioxide (CO2) levels, a key greenhouse gas driving climate change. Now, a team of researchers has found a surprising connection: these elevated CO2 levels are not just in the atmosphere, but also in our blood. In a 20-year study of health data from a US population database, scientists detected shifts in blood chemistry that align with increased CO2 exposure.
While the changes are not yet dangerous, the trend is alarming. According to the researchers' modeling, if current trends persist, some blood chemistry values could approach the limit of today's accepted healthy range by around 2076. This means that over time, we may see physiological changes at the population level.
"What we're seeing is a gradual shift in blood chemistry that mirrors the rise in atmospheric carbon dioxide, which is driving climate change," says respiratory physiologist Alexander Larcombe of Curtin University in Australia. "If current trends continue, modeling indicates average bicarbonate levels could approach the upper limit of today's accepted healthy range within 50 years. Calcium and phosphorus levels could also reach the lower end of their healthy ranges later this century."
The study examined blood chemistry data from the US National Health and Nutrition Examination Survey (NHANES), which collected samples from approximately 7,000 Americans every two years between 1999 and 2020. The researchers found that the average blood concentration of bicarbonate rose from 23.8 to 25.3 milliequivalents per liter, an increase of about 7 percent, or 0.34 percent per year. This paralleled the rise in CO2 over the same time period.
Meanwhile, calcium and phosphorus levels in the cohort showed the opposite trend, with calcium dropping by 2 percent and phosphorus by 7 percent. This may be related to the fact that when carbon dioxide dissolves in the bloodstream, it alters the body's acid-base balance. To keep blood pH within its narrow healthy range, the kidneys conserve bicarbonate, a buffering molecule that helps neutralize excess acidity. Bones can also buffer acid by exchanging minerals such as calcium and phosphorus.
At the moment, these shifts are small and within the body's tolerable range. However, the parallel rise is striking. If the researchers are correct, we may see physiological changes at the population level over time. "I actually think that what we are seeing is because our bodies are not adapting. It appears we are adapted to a range of CO2 in the air that may now have been surpassed," says retired geoscientist Phil Bierwirth, a colleague of Larcombe's.
"The normal range maintains a delicate balance between how much CO2 is in the air, our blood pH, our breathing rate, and bicarbonate levels in the blood. As CO2 in the air is now higher than humans have ever experienced, it appears to be building up in our bodies. Maybe we can never adapt such that it is vitally important to limit atmospheric levels of CO2."
The research has been published in Air Quality, Atmosphere & Health. So, what do you think? Do you agree with the researchers' findings? Or do you have a different interpretation? Share your thoughts in the comments below!
