Fourier is credited with the discovery in 1824 that gases in the atmosphere might increase the surface temperature of the Earth. This was the effect that would later be called the greenhouse effect. He described the phenomenon in 1824 and then again in a very similar paper in 1827 whereby an atmosphere serves to warm a planet. This established the concept of planetary energy balance — that planets obtain energy from a number of sources that cause temperature increase. Planets also lose energy by infrared radiation (that Fourier called "chaleur obscure" or "dark heat") with the rate increasing with temperature. A balance is reached between heat gain and heat loss; the atmosphere shifts the balance toward the higher temperatures by slowing the heat loss. Although Fourier understood that the rate of infrared radiation increased with temperature, the Stefan–Boltzmann law which gives the exact form of this dependency (a fourth-power law) was not discovered until fifty years later, while Planck's law, which refines this dependency to include wavelength, took a further twenty years.
Fourier recognized that Earth primarily gets energy from Solar radiation, to which the atmosphere is largely transparent, and that geothermal heat doesn't contribute much to the energy balance. However, he mistakenly believed that there is a significant contribution of radiation from interplanetary space.
Fourier referred to an experiment by M de Saussure, who exposed a black box to sunlight. When a thin sheet of glass is put on top of the box, the temperature inside of the box increases.
Infrared radiation had been discovered by William Herschel in 1800. Fourier was familiar with Herschel's work, as indicated by the fact that he delivered a lecture in praise of Herschel in 1824.