US blood bicarbonate levels rise with atmospheric CO2 and could reach health limits in 50 years
Feb 28th 2026
An analysis of US NHANES data from 1999 to 2020 shows rising population average serum bicarbonate alongside falling calcium and phosphorus, a pattern the authors link to increasing atmospheric CO2 and warn could reach current healthy limits within decades if trends continue, while noting important uncertainties and the need for more research.
- Researchers analysed NHANES blood chemistry from 1999 to 2020 and found mean venous serum bicarbonate rose from about 23.8 to 25.3 mEq/L.
- Mean serum calcium fell roughly 2% and phosphorus fell roughly 7% across the same period.
- The authors say the bicarbonate increase parallels rising atmospheric CO2 and, if trends stay linear, predict venous bicarbonate could reach 30 mEq/L by 2076.
- Under the same linear assumptions they estimate calcium and phosphorus could hit their current lower healthy limits by about 2099 and 2085 respectively.
- The paper is observational and cannot prove causation, and the authors note uncertainties including measurement changes, time spent indoors, and possible non linear trends.
- Previous short term human and animal studies link elevated CO2 or bicarbonate to effects on cognition, oxidative stress, bone and kidney changes, but long term human evidence at projected ambient CO2 levels is limited.
- The authors call for more research and say substantial reductions in CO2 emissions are needed to address the potential public health risk.