Carbon dioxide overload, detected in human blood, suggests a potentially toxic atmosphere within 50 years

Abstract Anthropogenic activities are increasing the amount of carbon dioxide (CO 2 ) in the atmosphere. There is mounting experimental evidence that lifetime exposure to these increasing atmospheric CO 2 levels can negatively impact the normal physiology of organisms. However, directly assessing this in humans is very difficult. We analysed serum bicarbonate (HCO 3 − ), calcium (Ca) and phosphorus (P) levels from the U.S. National Health and Nutrition Examination Survey (NHANES) from 1999 to 2020 as indirect proxies for atmospheric CO 2 exposure. Over this period, average bicarbonate levels in this population show an increasing trend which parallels rising atmospheric CO 2 concentrations. Both Ca and P have decreased steadily over the same period. 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. Studies indicate that, after this time, elevated atmospheric carbon dioxide, leading to CO 2 accumulation in the body, has the potential to cause a range of adverse health effects. These findings highlight the urgent need for significant reductions in anthropogenic CO 2 emissions to safeguard public health.