Final answer:
Carbon dioxide, methane, and nitrous oxide are the three most important greenhouse gasses that contribute significantly to the greenhouse effect and climate change.
Step-by-step explanation:
The three most important greenhouse gasses that contribute to the greenhouse effect and climate change are carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). These gasses trap heat in the Earth's atmosphere similarly to how glass traps heat inside a greenhouse. Carbon dioxide is the primary greenhouse gas emitted through human activities, especially from the burning of fossil fuels and deforestation. Methane is released during the production and transport of coal, oil, and natural gas, as well as from livestock and other agricultural practices. Nitrous oxide, while less abundant, is a powerful greenhouse gas produced by soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning.