Vibrations of CO2 molecules and some other molecules in the Earth’s atmosphere play a key role in global warming because they strongly absorb radiation in the far infrared. The surface temperature of the Sun is 5800 K and the radiation emitted by the Sun peaks at about 500 nm. However, the surface of the Earth is at a much lower temperature, ∼300 K, and its radiation peaks at ∼10 µm. The Earth’s
atmosphere is largely transparent at visible and near infrared wavelengths and the Sun’s radiation passes through. However, the global-warming molecules absorb the Earth’s far infrared radiation and act to trap its energy. This effect leads to an increase in the surface temperature of the Earth.