Climate change, caused by greenhouse gas emissions from human activities, is leaving an ever-deeper mark on the planet and on living systems. A new investigation now says that these effects may already be found inside the human body.
In an article published in the journal ‘Air Quality, Atmosphere & Health’, two researchers from Australia analyzed more than 20 years of data on the population of the United States and say they have found changes in the chemical composition of the blood that suggest impacts from the atmospheric rise of carbon dioxide (CO2).
The duo found that average bicarbonate levels in human blood have risen by approximately 7% since 1999. Bicarbonate (HCO3−) is a by-product of the body’s metabolism and is considered an indicator of the CO2 concentration in the blood.
Bicarbonate is essential for maintaining the blood’s acid-base balance. When CO2 levels rise, the body retains more bicarbonate to stabilize the blood pH. However, over time this ongoing compensatory effort could have consequences.
The researchers say that this increase reflects the rise of CO2 in the atmosphere, whose concentration in 2000 was about 369 parts per million and currently exceeds 420 parts per million. Thus, they say the results suggest that the human body may already be trying to compensate for the effects of a changing atmosphere.
“What we’re seeing is a gradual change in the blood’s chemistry that reflects the increase in atmospheric carbon dioxide that is driving climate change,” says Alexander Larcombe, the study’s first author, a researcher at The Kids Research Institute Australia and affiliated with Curtin University and the University of Western Australia.
If the trend of increasing CO2 in the atmosphere continues, the team estimates that average bicarbonate levels in the blood could reach the maximum level considered safe for human health within 50 years.
The research also detected a decrease in circulating calcium and phosphorus in our bodies, and warns that these elements may fall to dangerous lows by the end of this century.
“As CO2 is now at levels higher than humans have ever experienced, it seems to be accumulating in our bodies,” says Phil Bierwirth, the other coauthor of the article, a member of the Australian National University.
“Perhaps we will never be able to adapt,” he adds, noting that “it is vitally important to limit CO2 levels in the atmosphere.”
Larcombe stresses that “we are not saying that people will get sick suddenly when we cross a certain threshold.” However, he acknowledges that the results suggest there could be “gradual physiological changes at the population level” and, he argues, “this is something we must monitor within the scope of future climate policies.”
