Final answer:
The most important trace gases are carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), which play crucial roles in Earth's greenhouse effect and are significant contributors to global climate change.
Step-by-step explanation:
The trace gases that are most important are carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). These gases, along with others like hydrofluorocarbons (HFCs) and sulfur hexafluoride (SF₆), play significant roles in the Earth's atmospheric processes, particularly the greenhouse effect which contributes to global climate change. While gases like neon and helium are present in the atmosphere, they do not actively participate in the heat-trapping greenhouse effect. Carbon dioxide's role is multifaceted as it is involved in the natural carbon cycle and is also the primary greenhouse gas contributing to recent climate change due to its increased concentration from human activities such as the burning of fossil fuels and changes in land use. Methane and nitrous oxide are also crucial due to their high global warming potential, which considerably impacts the climate despite their lower atmospheric concentrations compared to CO₂.