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EXISTENTIAL DEAD-END: Has humanity «breathed in» global warming?

EXISTENTIAL DEAD-END: Has humanity «breathed in» global warming?
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Lina Chanturia. Image, from the series «Metamorphosis», 2023 / Artwork:


Climate change — is the global problem of the 21st century. Therefore, we are encouraged to counteract warming in a variety of ways. For example, eating less meat and reducing the number of livestock that emit methane into the atmosphere. Or give up internal combustion engines and switch to bicycles.

However, if these tasks, although difficult, are more or less solvable, there is one significant problem, which in general, is not solvable. British scientists believe that among the main culprits of global warming are not only cows and cars but also… human breathing.



Much has been said about the carbon footprint, which is the cause of global warming, both by scientists and the popular media. This footprint, in one way or another, is left by each of us using light, electricity, heat, turning on the TV, going on vacation by plane, or driving a car.

In this way, excess CO2 and some other greenhouse gases appear in the atmosphere. Their impact on all living things, including humans, is catastrophic since the climate has never changed so rapidly in the history of the Earth.

In fact, all of the above is the so-called «scientific consensus» on climate change. But that is exactly what the latest study by British scientists has aimed at.




Quite «unpleasant» in its conclusions for mankind, the research project in question is headed by Nicholas Cowan. He is a respected scientist, Doctor of Science, atmospheric physicist from the UK Center for Ecology and Hydrology in Edinburgh.

Most of us remember from school science lessons that humans breathe in oxygen and breathe out carbon dioxide. But this is, to put it mildly, not true.

Cowan calculated the composition of gases exhaled by humans with scientific precision: nitrogen (N) — 78%; oxygen (О2) — 17%; carbon dioxide (CO2) — 4%; other gases, including methane (CH4), and nitrous oxide (N2O) — 1%.




According to our school course, when we inhale, air enters the lungs, where oxygen is absorbed into the blood, and carbon dioxide moves from the blood into the lungs and is exhaled. This process supposedly distinguishes us from plants, with which the opposite is true.

They utilize CO2 and release oxygen as a byproduct of photosynthesis. But as Cowan’s data shows, the popular science myths formed in childhood don’t hold up to scrutiny.

In terms of respiration, man behaves not only like an animal but also like a plant. He gives into the atmosphere not only carbon dioxide but also oxygen, which probably many of you have not realized before. But it gives out far less than it takes in.


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In view of the above, British scientists have expressed the opinion that breeding cows and operating cars are not the only evils that can happen to the Earth’s atmosphere. Quite decent troubles to it are caused by man. And not even by his household and economic activity but by the direct fact of his existence. 

The fact is that the person… simply breathes! And his breath turns out to be quite deadly for the atmosphere. In the UK, human breath is responsible for 0.1% of greenhouse gas emissions. What about China and India, where no measurements have been taken? Empirically it is clear that in these countries the figure should be higher.



You might think that 0.1% is some insignificant trifle that could be neglected. But the catch is in the composition of the gas mixture you and I exhale. In addition to CO2, our breath contains at least two other greenhouse gases — methane and nitrous oxide. And it is these that scientists characterize as more powerful in their impact on the atmosphere and, consequently, more harmful to the climate than CO2. But that’s not all.

In addition to methane and nitrous oxide, people emit many other things. Apparently, the 0.1% does not include burping, for example. A lot of emissions also come from our skin — not only during intense physical activity but in any condition, constantly and unnoticed by us.




Nicholas Cowan’s verdict is unequivocal: «Exhaled human breath can contain small, elevated concentrations of methane (CH4) and nitrous oxide (N2O), both of which contribute to global warming». Cowan urged vigilance. Because the emissions that humans release into the atmosphere are generally considered insignificant. And very much for nothing!

Inside the human body, methane is produced by methanogens — colonies of microorganisms that live in our digestive tract. Methane then enters the bloodstream, and from there, it is transported to the lungs, which expel it outside. It’s a similar story with nitrates in food and water, which are converted into nitrous oxide.

Scientists believe that CH4 and N2O are potent greenhouse gases, but because they are exhaled in much smaller quantities, their significant contribution to global warming may not be accounted for. The contribution to climate change of CO2 from human breath, on the other hand, is just about zero, according to Cowan.




The research involved 104 adult volunteers from the UK. They were asked to take a deep breath, hold it for 5 seconds, and then exhale into a plastic bag. After that, the bag was tightly closed, and its contents were subjected to chemical analysis while recording the age, gender, and dietary preferences of the subjects. In this way, 328 breath samples were collected.

Specialists found that nitrous oxide was released by each participant, but methane through the breath — only 31%, the rest released it in a way that is not very acceptable for decent society… Methane in the breath was most often found in women over 30 years old, but scientists have not understood why.

In addition, scientists were unable to find any link between gases in the breath and diet. So meat-eaters can relax — they are no more guilty of global warming than anyone else. The bad news is quite different — humankind is able to eat less beef, but it is unlikely to breathe less!



Measurements of methane and nitrous oxide in human breath and the development of UK scale emissions Ben Dawson, Julia Drewer, Toby Roberts, Peter Levy, Mathew Heal, Nicholas Cowan Published: December 13, 2023


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