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Greenhouse gases that cause climate change

June 27, 2021 | Charles Lin

Image by mohamed Hassan from Pixabay

Image by mohamed Hassan from Pixabay

What do human breath, cow burps, and laughing gas have in common? Our exhaling can cause a stale air feeling in a crowded room with poor ventilation. Cow burps are a result of fermentation process in the cow’s stomach. Laughing gas is sometimes used by dentists as a mild sedative. In chemistry-speak, our breath is made up of carbon dioxide (CO2), cow burps consist of methane (CH4), and laughing gas is nitrous oxide (N2O). It turns out CO2, CH4 and N2O are all greenhouse gases produced by human industrial and agricultural activities; they trap energy from the sun and drive climate change through the greenhouse effect.

CO2 enters the atmosphere through different natural sources including plant and animal respiration, and is removed from the atmosphere through photosynthesis of plants and ocean uptake. Humans add CO2 to the atmosphere by burning fossil fuels (coal, oil, and natural gas), and deforestation and land clearing. The manufacture of cement is another important source.

Fossil fuel plants generate CO2

Wetlands are the largest natural source of CH4. Human activities add CH4 through rice paddies, landfills and sewage, cattle and sheep raising (burping and farting from cows!), and artificial wetlands. CH4 is also produced when fossil fuels or trees are burned with insufficient oxygen for complete combustion. It can also leak to the atmosphere from extraction and processing of fossil fuels.


We add N2O to the atmosphere through the use of synthetic fertilizers and manure to improve crop productivity, and cultivation of certain crops. N2O is also produced through combustion of fossil fuels and biomass (e.g., trees or wood-based fuels) and from some industrial sources.

Fertilizing a field

There is a fourth GHG that is entirely made by humans – halocarbons. These are synthetic chemicals from industrial processes such as the use of refrigerants, aluminum production, and manufacturing of semi-conductors.

Like the ones powering the device you are using right now

This is quite a list of chemicals making up GHGs that are part of our everyday life; you can read more here (page 42) or here. Now this is the problem: our activities are adding these GHGs to the atmosphere faster than their removal by natural processes, leading to their buildup and causing climate change.

What can we do? In short, we need to reduce our production of GHGs, through mitigation measures such as reaching net zero by 2050. Join the action!

Charles Lin

Charles is a retired atmospheric scientist based in Toronto. He stays busy as founder and lead of ImpactNetZero, keeping healthy in mind and body, and reading stories to his two grandchildren.

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