Researchers have identified a 20-year trend of shifting blood markers in the U.S. population that mirrors the steady increase of atmospheric carbon dioxide.

A new study published in Air Quality, Atmosphere and Health suggests that rising atmospheric carbon dioxide levels may be influencing human biology. Researchers from The Kids Research Institute Australia, Curtin University, and The Australian National University analyzed over two decades of U.S. health data, identifying persistent shifts in blood chemistry that track with the upward trend of atmospheric CO2.

Study Methodology and Findings

The research team utilized data from the U.S. National Health and Nutrition Examination Survey (NHANES), examining blood test results from approximately 7,000 individuals at two-year intervals between 1999 and 2020. During this period, atmospheric CO2 concentrations rose from roughly 369 parts per million (ppm) in 2000 to over 420 ppm today. The analysis revealed that average serum bicarbonate levels increased by about 7 percent since 1999. Bicarbonate is a marker used by the body to regulate acid-base balance, and its retention can help keep blood pH stable as CO2 levels rise. Conversely, the study found that average levels of calcium and phosphorus decreased over the same timeframe.

Potential Health Implications

Study authors noted that while these changes may represent the body's attempt to maintain physiological balance, the long-term effects remain a concern. Associate Professor Alexander Larcombe suggested that younger generations, whose bodies are still developing, may face the greatest lifetime exposure to these elevated levels. The researchers cautioned that calcium and phosphorus levels could potentially reach the lower end of their healthy ranges later this century. Dr. Phil Bierwirth, a co-author and retired environmental geoscientist, stated that the findings do not prove a direct cause-and-effect relationship but indicate that human bodies may be struggling to adapt to CO2 concentrations that have surpassed historical ranges. The team recommends that future climate policy discussions incorporate these biological markers as a long-term public health factor alongside traditional environmental indicators.