The major contributor to global warming is:

Question

Accepted Answer

The major contributor to global warming is carbon dioxide ($CO_{2}$), which is identified as Option 3. Here is a detailed explanation supporting why $CO_{2}$ is the correct answer, along with reasons why the other options are incorrect:

1. **Why $CO_{2}$ is the Correct Answer:**
   - **Abundance and Persistence:** Carbon dioxide is the most abundant greenhouse gas emitted by human activities, primarily from the burning of fossil fuels such as coal, oil, and natural gas. It accounts for the largest share of greenhouse gases in the atmosphere.
   - **Long Atmospheric Lifetime:** $CO_{2}$ has a long atmospheric lifetime, meaning it remains in the atmosphere for a long time, contributing to the greenhouse effect and global warming over extended periods.
   - **Significant Impact on Climate:** The increase in $CO_{2}$ levels is closely linked to the rise in global temperatures. It traps heat in the Earth's atmosphere, leading to the warming of the planet, which is a primary driver of climate change.

2. **Why the Other Options are Incorrect:**
   - **CFCs (Option 1):** Chlorofluorocarbons (CFCs) are potent greenhouse gases and have a high global warming potential. However, their concentration in the atmosphere is much lower compared to $CO_{2}$. Additionally, international agreements like the Montreal Protocol have significantly reduced their emissions.
   - **$N_{2}O$ (Option 2):** Nitrous oxide is another greenhouse gas with a high global warming potential, but it is present in much smaller quantities than $CO_{2}$. Its sources include agricultural activities and industrial processes, but its overall contribution to global warming is less than that of $CO_{2}$.
   - **$CH_{4}$ (Option 4):** Methane is a potent greenhouse gas with a higher warming potential than $CO_{2}$ on a per molecule basis. However, it is present in much lower concentrations in the atmosphere. While it is a significant contributor to global warming, its overall impact is still less than that of $CO_{2}$ due to its lower abundance.

In conclusion, while other greenhouse gases like CFCs, $N_{2}O$, and $CH_{4}$ contribute to global warming, $CO_{2}$ is the major contributor due to its high concentration, long atmospheric lifetime, and significant impact on the Earth's climate.