Final answer:
CO2 is focused on more than water vapor because CO2 levels are increased by human activities, leading to additional greenhouse effects, while water vapor is mainly controlled by temperature. CO2 has a longer atmospheric lifetime than methane and contributes significantly to long-term climate change.
Step-by-step explanation:
One of the main reasons that CO2 is more focused on than water vapor in discussions about global warming is that although water vapor is responsible for the majority of the natural greenhouse effect, its concentration in the atmosphere is primarily controlled by temperature. On the other hand, CO2 levels are rapidly increased by human activities, especially the burning of fossil fuels, which adds to the greenhouse effect and has long-term effects on the climate.
Water vapor has a short atmospheric lifetime, and its global concentration is not significantly affected by direct human emissions. CO2, however, continues to accumulate in the atmosphere, thus retaining heat for much longer periods. While water vapor levels respond to temperature changes and can provide a feedback mechanism, CO2 levels are directly influenced by human activity, making it a critical focus for climate change mitigation.
Furthermore, methane (CH4), although more potent than CO2, is at a lower concentration and shorter-lived. The focus thus remains on CO2 because of its prevalent anthropogenic emission and longer residence time in the atmosphere.