Human breathing also contributes to global warming.

The authors argue that the role of human breathing in climate change has been underestimated and needs further study.

Specifically, after measuring the gas composition in the breath of 328 study participants, the researchers concluded that human breath accounts for 0.05% of the UK's methane (CH4) emissions and 0.1% of nitrous oxide (N2O).

Both gases “have a much higher global warming potential than carbon dioxide (CO2),” the study notes.

"We advise caution in assuming that human emissions are negligible," the team, led by atmospheric physicist Nicholas Cowan at the UK Centre for Ecology and Hydrology, noted.

While “the contribution of CO2 in human breath to climate change is essentially zero” because plants absorb almost all of it, the two gases remain in the atmosphere, Mr. Cowan explained.

Methane traps 80 times more heat than CO2 in its first 20 years in the atmosphere. A detailed analysis of the diets of test subjects found no evidence that meat eaters produced more of the gas. While all test subjects exhaled nitrous oxide, only 31% exhaled methane.

These individuals — referred to as “methane producers” in the paper — were more likely to be female and over 30 years old, although the researchers couldn’t determine why that was.

The authors caution that their study only looked at breath and call for further research into the full picture of human emissions. Further research could reveal more about the “impact of aging populations and changing diets” on the planet.

Minh Hoa (reported by Tuoi Tre and Lao Dong)

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