Increased CO2 levels in the atmosphere have correlated to an increase in bicarbonate (HCO3-) levels and a decrease in calcium (Ca) and phosphorus (P) levels in human blood, according to a study published in the journal Air Quality, Atmosphere & Health. If these trends continue, “blood bicarbonate values could be at the limit of the accepted healthy range in half a century, and Ca and P will be at the limit of their healthy ranges by the end of this century”.
In human blood, CO2 is converted into bicarbonate, which at normal concentrations has an important role in maintaining healthy pH levels. However, the concentration of bicarbonate increased by about 7%, or 0.34% a year, between 1999 and 2020. Calcium and phosphorus levels dropped by 2% and 7% respectively. This is because when carbon dioxide dissolves in the bloodstream it “alters the body’s acid base balance”, said Science Alert. In order to keep the blood pH within its healthy range, the “kidneys conserve bicarbonate, a buffering molecule that helps neutralise excess acidity”. Bones “can also buffer acid by exchanging minerals such as calcium and phosphorus”.
Rising CO2 levels are “especially relevant for children and adolescents, whose developing bodies will experience the longest cumulative exposure”, said a release about the study. “We’re not saying people are suddenly going to become unwell when we cross a certain threshold,” said Professor Alexander Larcombe, a respiratory physiologist and author of the study. “But this suggests that there may be gradual physiological changes occurring at a population level, and that’s something we should be monitoring as part of future climate change policy.” | 
