CO2 Creep Is Quietly Rewriting Blood Chemistry

The air you breathe every day may be quietly changing what’s inside your veins.

Story Snapshot

A new study finds serum bicarbonate in Americans rose about 7% between 1999 and 2020, tracking rising atmospheric carbon dioxide (CO2).
The same research links falling calcium and phosphorus levels to the same time period.
Researchers warn that if trends hold, bicarbonate could near the edge of the healthy range within 50 years.
The findings come from a huge United States health survey, not a lab experiment on live subjects.

What The Study Actually Found

Researchers Peter Larcombe and Philip Bierwirth looked at more than 20 years of blood data from the National Health and Nutrition Examination Survey. They found average serum bicarbonate climbed to 25.3 milliequivalents per liter by 2019 and 2020, up roughly 7% from 1999. Bicarbonate is the compound your blood uses to carry carbon dioxide out of your body and keep its acid balance steady.

Alongside that rise, the study reports a steady drop in calcium and phosphorus, two minerals tied up in the same acid-buffering chemistry. The authors argue these shifts line up closely with the decades-long climb in atmospheric CO2, which has pushed past levels humans have ever lived through before now.

Why Your Body Reacts To More Carbon Dioxide

When you inhale more CO2, it dissolves into your blood and reacts with water, forming carbonic acid. That acid splits into hydrogen ions and bicarbonate. Your body naturally holds onto more bicarbonate to keep blood pH stable, since even small pH swings can disrupt organ function. Scientists have long known short bursts of high CO2 raise blood acidity and breathing rate; this study suggests a slow, year-after-year version of that same process.

The researchers frame their bicarbonate numbers as a kind of stand-in for lifelong CO2 exposure, since no one tracks that directly for a whole population over 20 years. Bicarbonate has a normal adult reference range of about 22 to 29 millimoles per liter, according to federal lab standards. The 2019-2020 average of 25.3 sits inside that range today, but the researchers say the trajectory matters more than the current number.

The Long-Term Math Behind The Warning

Project the current trendline forward, and the authors calculate bicarbonate levels could approach the top of the healthy range within roughly 50 years. Calcium and phosphorus, moving in the opposite direction, could hit the low edge of their healthy ranges by the end of this century on the same math. Those are projections built on two decades of survey data, not a guarantee, but the pattern is consistent enough that the authors call it a public health signal worth watching now rather than later.

Children and teenagers may face greater long-term exposure simply because they have more years ahead of them breathing higher-CO2 air, according to summaries of the paper. That detail matters for parents and doctors thinking about pediatric health screening decades from now, even though the current study doesn’t diagnose disease in any individual patient today.

What Doctors Already Know About Bicarbonate And Health

Bicarbonate and pH tests are standard tools doctors already use to catch acid-base problems tied to kidney disease, breathing disorders, and metabolic conditions. That existing medical infrastructure means any real population shift in these markers would show up in the same bloodwork millions of Americans get every year during routine checkups, giving physicians a built-in early warning system if the trend accelerates.

Separate lab research has shown that higher CO2 concentrations can boost inflammatory markers in blood samples under low-oxygen conditions, adding a possible mechanism behind the numbers. None of this proves a specific disease outcome yet, but it gives doctors and researchers a concrete, measurable trail to keep following as global CO2 levels keep climbing year after year.

This study shows that, due to climate change, our blood chemistry has shifted 7% since 1999 and will make us sick in appx. 50 years. It's called metabolic alkalosis. https://t.co/EaJxZen9Q7

— Karen Piper (@PiperK) August 18, 2026

For everyday Americans, the takeaway isn’t panic, it’s awareness. Routine bloodwork already tracks these exact markers, so patients can ask their doctors about bicarbonate, calcium, and phosphorus trends at their next physical. A slow-moving, well-documented shift in basic body chemistry deserves steady monitoring, not alarmist headlines, especially since the current averages remain within normal medical ranges today.