If there is no greenhouse effect, then the average temperature at surface of earth would have been

Options

A. `15^(@)C`
B. `-18^(@)C`
C. `-6^(@)C`
D. `10^(@)C`

Explanation

To solve the question regarding the average temperature at the surface of the Earth if there were no greenhouse effect, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Greenhouse Effect**:
- The greenhouse effect is a natural process where certain gases in the Earth's atmosphere (like carbon dioxide, methane, and chlorofluorocarbons) trap heat. This keeps the Earth's surface warm and hospitable for life.

2. **Identify the Role of Greenhouse Gases**:
- Greenhouse gases absorb and emit long-wave radiation, preventing a significant portion of this energy from escaping into space. This process helps maintain the Earth's average temperature.

3. **Consider the Implications of No Greenhouse Effect**:
- If there were no greenhouse gases, the heat that the Earth receives from the sun would not be trapped. As a result, the temperature would drop significantly.

4. **Determine the Current Average Temperature**:
- The current average temperature of the Earth, with the greenhouse effect, is approximately 15 degrees Celsius.

5. **Estimate the Temperature Without Greenhouse Effect**:
- Without the greenhouse effect, the average temperature of the Earth would fall drastically. Based on scientific estimates, it is suggested that the average temperature could drop to around -18 degrees Celsius.

6. **Select the Correct Answer**:
- From the options provided (15°C, -18°C, -60°C, -10°C), the correct answer is **-18 degrees Celsius**.

### Final Answer:
If there is no greenhouse effect, then the average temperature at the surface of the Earth would have been **-18 degrees Celsius**.

---