Rising greenhouse gas emissions (GHG) are the key cause of climate change. While certain GHGs occur naturally, human activities generate the now observable drastic increase.
Carbon dioxide, methane, nitrous oxide or nitrogen protoxyde, and ozone are the main gases responsible for the greenhouse effect.
The greenhouse effect is a natural phenomenon disrupted by human activity
Carbon dioxide (CO2) is emitted naturally through breathing and the decomposition of living beings. Forests, soil, and the oceans absorb and store part of the atmospheric CO2. The presence of natural GHG contributes to the greenhouse effect, a phenomenon that is essential to life on Earth.
The natural greenhouse effect enables us to live comfortably on our planet. Indeed, the average temperature on Earth is 15°C. On Mars, which is devoid of the greenhouse effect, the average temperature is ‑50°C. On Venus, where the atmosphere is heavily laden with carbon dioxide, the average temperature is 420°C.
Aside from greenhouse gases of natural origin, human activities release GHG into the atmosphere. Such activities generate abundant amounts of GHG, which come above all from the combustion of fossil energies such as coal, oil, and natural gas.
For example, the transportation, industry, and building sectors produce more than 80% of Québec’s GHG emissions. Agricultural activities, raising animals, and waste in dumps also produce significant amounts of methane (CH4), a powerful GHG.
Several other human activities and inventions release GHG. For example, air conditioning systems, refrigerators, and freezers contain synthetic fluorinated gases such as halocarbons, which are highly polluting gases. Halocarbons contribute to two major environmental problems: the thinning of the ozone layer and climate change.