Which Greenhouse Effect and Global Warming term is correctly associated with major source or process: “released notably by fossil-fuel combustion and deforestation”, and also with “the largest contributor to human-caused long-term warming”?

Correct Answer: Option B — Carbon dioxide. Carbon dioxide is correct because it is released notably by fossil-fuel combustion and deforestation. Carbon dioxide is also associated with the largest contributor to human-caused long-term warming. A further identifying fact is that Carbon dioxide is the largest contributor to human-caused long-term warming. Another useful fact is that Carbon dioxide is associated with forests and oceans absorb part of its emissions. Why the other options are incorrect: Option A — Methane: It is emitted by livestock, wetlands, landfills and fossil-fuel systems and is associated with warms more strongly per molecule than carbon dioxide over shorter periods. Option C — Nitrous oxide: It is strongly linked to agricultural soils and nitrogen fertilisers and is associated with also contributes to stratospheric ozone depletion. Option D — Water vapour: It is enters the atmosphere mainly through evaporation and is associated with acts mainly as a climate feedback rather than the initial human forcing. Exam Takeaway: Link Carbon dioxide with “released notably by fossil-fuel combustion and deforestation” and “the largest contributor to human-caused long-term warming” for quick revision.