State the cause of increase of green house effect.

The main causes are ----

1. Burning of fossil fuel , for electricity , heat , cooking , transportation ,industry etc.

2. Excessive use of fertilizers in agriculture , which emit $N_{2}O$ (one of the green house gases) in the atmosphere .

3. Decrease in plantation , due to so called development . Plants are good absorbers of $C{O}_2$ , but now their number is decreasing , so amount of $C{O}_2$ is increasing .

4. Excessive use of air conditioners and leakage of freezer gases , called HFC .