Carbon dioxide (CO2) contributes to the warming of the planet because it is a heat-trapping gas. It absorbs and emits infrared radiation, which helps to retain heat in the Earth's atmosphere. This phenomenon is known as the greenhouse effect. When sunlight reaches the Earth, some of it is reflected back into space, while some is absorbed and warms the surface. The Earth then emits this heat as infrared radiation. Greenhouse gases like CO2 trap some of this heat, preventing it from escaping back into space, thus contributing to an increase in global temperatures.
So, the correct statement would be: It is a heat-trapping gas.