Scientists detect a surprising shift in human blood as CO2 rises
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- Researchers from The Kids Research Institute Australia, Curtin University and ANU, analyzing NHANES blood tests from roughly 7,000 people at two-year intervals between 1999 and 2020, found average serum bicarbonate rose about 7% while calcium and phosphorus levels fell.
- A/Prof Alexander Larcombe said modeling indicates that if trends continue, average bicarbonate levels could approach the upper limit of today's accepted healthy range within 50 years, and calcium and phosphorus could reach the lower end of their healthy ranges later this century.
- Dr. Phil Bierwirth stressed the study does not establish direct cause-and-effect, but argued the consistency of changes across a large population suggests humans are not adapting: "we are adapted to a range of CO2 in the air that may now have been surpassed."
- Atmospheric CO2 climbed from roughly 369 ppm in 2000 to more than 420 ppm today, rising about 2.6 ppm per year on average over the past decade, with 2024 alone adding 3.5 ppm.
- The study, published in Air Quality, Atmosphere and Health, recommends tracking atmospheric composition alongside population-level biological markers as part of future climate change policy.
- Children and teenagers are flagged as facing the greatest lifetime exposure because their bodies are still developing — a cohort that won't reach the projected 50-year threshold but will live with these shifting baselines the longest.
Why it matters: If the trend holds, the average U.S. adult's blood chemistry could sit at the upper edge of today's 'normal' bicarbonate range by the 2070s — forcing clinicians and pediatricians to decide what counts as healthy for a generation whose physiology was shaped by CO2 levels humanity never evolved with.
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