Carbon dioxide (CO₂), primarily known for its role in global warming, might be leaving a closer mark on human health. A recent study, utilizing health data from the US population collected between 1999 and 2020, hypothesizes that the sustained increase of atmospheric CO₂ could be reflected in certain blood indicators. Researchers observed that average serum bicarbonate increased by approximately 7% during this period, while calcium and phosphorus levels decreased. These changes temporally align with atmospheric CO₂ rising from about 369 parts per million to over 420 ppm.
The human body maintains a precise chemical balance, particularly in the blood, where bicarbonate acts as a buffer to keep pH stable. However, the study's authors emphasize that this is a statistical association, not a direct demonstration of cause and effect. Numerous alternative explanations need consideration, such as dietary modifications, disease prevalence, medical treatments, lifestyle changes, or even variations in laboratory techniques over the decades.
The researchers made a projection based on the detected trends, suggesting that if they continue, the average bicarbonate level could approach the upper limit of the healthy range within about fifty years. The study pays particular attention to children and adolescents, who will accumulate more years of exposure to a changing atmosphere. The research proposes incorporating biological markers into environmental monitoring as a tool to detect slow changes before they become difficult-to-correct public health issues.
While CO₂ remains primarily a climate issue, this research suggests it could also be a long-term health variable. To confirm whether this lead points to a real risk, science will require more data, studies in other countries, and physiological tests capable of distinguishing coincidence from causality.
