Relative contribution of various green house gases to total global warming in ascending order is :

Question

Accepted Answer

Option 2 is the correct answer: CO2 > CH4 > NO2 > CFCs. This order reflects the relative contribution of various greenhouse gases to total global warming based on their abundance and global warming potential (GWP).

1. **Explanation for Option 2:**
   - **CO2 (Carbon Dioxide):** Carbon dioxide is the most significant greenhouse gas emitted by human activities, primarily from burning fossil fuels and deforestation. It has the highest concentration in the atmosphere among the greenhouse gases, making it the largest contributor to global warming.
   - **CH4 (Methane):** Methane is the second most significant greenhouse gas. Although it has a higher global warming potential than CO2, its concentration in the atmosphere is much lower. Methane is released from sources such as agriculture (especially rice paddies and livestock), landfills, and natural gas production.
   - **NO2 (Nitrous Oxide):** Nitrous oxide has a higher global warming potential than both CO2 and CH4, but its atmospheric concentration is even lower than methane. It is primarily emitted from agricultural activities and industrial processes.
   - **CFCs (Chlorofluorocarbons):** CFCs have the highest global warming potential among these gases, but their concentration is the lowest due to international regulations like the Montreal Protocol, which have significantly reduced their emissions.

2. **Explanation for why other options are incorrect:**
   - **Option 1 (CO2 > CFC > CH4 > NO2):** This option incorrectly places CFCs before CH4 and NO2. While CFCs have a high global warming potential, their atmospheric concentration is much lower due to regulatory measures, making their overall contribution to global warming less than that of CH4 and NO2.
   - **Option 3 (CH4 > CFC > CO2 > NO2):** This option incorrectly suggests that CH4 contributes more to global warming than CO2, which is not accurate given the much higher concentration of CO2 in the atmosphere. Additionally, it places CFCs before CO2, which is incorrect for the same reasons mentioned above.
   - **Option 4 (CFC > CH4 > CO2 > NO2):** This option incorrectly ranks CFCs as the highest contributor to global warming. Despite their high global warming potential, their reduced concentration due to international agreements means they contribute less than CO2, CH4, and NO2.

In conclusion, Option 2 accurately reflects the relative contributions of these greenhouse gases to global warming, considering both their atmospheric concentrations and global warming potentials.