PREVIOUSLY ASKED IN:
WBPSC Miscellaneous Preliminary 2019
Answer
H2O vapour
Explanation
By volume and mass, water vapor (H2O vapour) is the most abundant greenhouse gas in the Earth's atmosphere. It accounts for the largest percentage of the natural greenhouse effect (around 60-70%). However, it is highly variable and its lifecycle in the atmosphere is very short. When discussing long-term, human-induced (anthropogenic) climate change, Carbon Dioxide (CO2) is considered the primary driver.
Key Points
- > Water vapor is the largest contributor to the natural greenhouse effect.
- > Carbon dioxide (CO2) is the primary greenhouse gas emitted through human activities.
- > Methane (CH4) is much more efficient at trapping radiation than CO2 (approx 25 times), also known as marsh gas.
- > Carbon monoxide (CO) is not technically a direct greenhouse gas, but it acts as an indirect greenhouse gas.
- > Other significant greenhouse gases include Nitrous Oxide (N2O), CFCs, and Ozone (O3).
Additional Information
Major Greenhouse Gases in Atmosphere
| Gas Name | Source | Key Feature |
|---|---|---|
| Water Vapor | Evaporation | Most abundant by volume globally |
| Carbon Dioxide | Fossil fuels, deforestation | Primary driver of anthropogenic warming |
| Methane (CH4) | Wetlands, agriculture | Higher Global Warming Potential than CO2 |
| Nitrous Oxide | Fertilizers, industries | Also known as 'laughing gas' |
Memory Tips
- Trick for Exams: If asked for the "most abundant overall," it is Water Vapor. If asked for the "principal gas driving recent climate change," it is CO2.