$CO_2$ is called a greenhouse gas because ......

Explain the causes,effects,and control of global warming.

The two gases that contribute most significantly to the greenhouse effect are . . . . . . .

If there were no $CO_2$ in the Earth's atmosphere,the temperature of the Earth's surface would be ..........

The given diagram represents the greenhouse effect.
$I.$ Greenhouse gases absorb infrared radiation from the earth. The absorbed radiations are again emitted towards the earth's surface,heating it up.
$II.$ $CO_{2}, CH_{4}, CFCs$ and $N_{2}O$ are the gases responsible for the greenhouse effect.
$III.$ An increase in the level of greenhouse gases results in considerable heating of the earth,leading to global warming.
Which of the statements given above are correct?

Excess atmospheric $CO_2$ increases the greenhouse effect because it: