Scientists detect a surprising shift in human blood as atmospheric CO2 rises
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- Researchers from The Kids Research Institute Australia, Curtin University, and ANU analyzed blood samples from roughly 7,000 people via the U.S. NHANES survey at two-year intervals between 1999 and 2020, finding average serum bicarbonate climbed ~7% while calcium and phosphorus levels declined.
- Study author Alexander Larcombe said the blood chemistry shifts closely mirror the rise in atmospheric CO2 from ~369 ppm in 2000 to over 420 ppm today, describing it as 'a gradual shift in blood chemistry that mirrors the rise in atmospheric carbon dioxide.'
- Modeling published in Air Quality, Atmosphere and Health suggests that if current trends continue, average bicarbonate levels could approach the upper limit of the accepted healthy range within 50 years, with calcium and phosphorus reaching the lower end later this century.
- Co-author Phil Bierwirth stressed the study does not establish causation, but said the consistency across a large population suggests humans aren't adapting well to CO2 concentrations now exceeding the ~280–300 ppm range humans evolved under.
- The researchers recommend that atmospheric CO2 be tracked alongside biological markers across populations, framing rising CO2 as a long-term public health factor that hits developing bodies hardest—children and teens face the greatest lifetime exposure.
Why it matters: If the trend holds, a blood marker tied to the body's acid-base balance could push to the upper edge of the healthy range within 50 years, adding a biological dimension to the climate policy debate that hits children the hardest since their developing bodies will accumulate the most lifetime CO2 exposure.
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