Why is CO2 considered a greenhouse gas and how does it contribute to global warming?

Carbon dioxide (CO2) is considered a greenhouse gas because it traps heat in the Earth's atmosphere. When sunlight reaches the Earth's surface, some of the energy is absorbed and re-emitted as infrared radiation. Greenhouse gases like CO2 absorb and trap this infrared radiation, preventing it from escaping into space. This trapped heat leads to an increase in the Earth's temperature, known as global warming.