Rising atmospheric CO2 may already be influencing human biology, with new research identifying long-term shifts in blood chemistry that have tracked increases in atmospheric concentrations.
Scientists from The Kids Research Institute Australia, Curtin University and The Australian National University (ANU) analysed more than 20 years of US health data, covering around 7,000 people surveyed between 1999 and 2020.
The study found that average serum bicarbonate (pH balancing chemical) levels rose by around 7% during the period and calcium and phosphorus concentrations declined. The changes coincided with atmospheric CO2 increasing from about 369 parts per million (ppm) in 2000 to more than 420 ppm today.
Higher CO2 concentrations can cause the body to retain more bicarbonate to maintain acid-base balance.
Study author, Professor Alexander Larcombe says the findings point to a potential biological response to changing atmospheric conditions.
He said: “What we’re seeing is a gradual shift in blood chemistry that mirrors the rise in atmospheric carbon dioxide, which is driving climate change.”
“If current trends continue, modelling indicates average bicarbonate levels could approach the upper limit of today’s accepted healthy range within 50 years.”
The researchers say the study does not prove atmospheric CO2 directly caused the observed changes with the expectation that children and teenagers could face the greatest lifetime exposure to elevated CO2 because their bodies are still developing.
They recommend monitoring atmospheric composition alongside biological markers to better understand potential health effects over coming decades.
Professor Larcombe also says that the rise in emissions should be considered alongside established climate-related health risks.
He said: “This suggests there may be gradual physiological changes occurring at a population level, and that’s something we should be monitoring as part of future climate change policy.”
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