Green House Effect

The greenhouse effect is caused by an atmosphere containing gases that absorb and emit infrared radiation. Greenhouse gases trap heat within the surface-troposphere system, causing heating at the surface of the planet or moon. This mechanism is fundamentally different from that of an actual greenhouse, which works by isolating warm air inside the structure so that heat is not lost by convection. The greenhouse effect was discovered by Joseph Fourier in 1824, first reliably experimented on by John Tyndall in 1858, and first reported quantitatively by Svante Arrhenius in 1896.

The black body temperature of the Earth is 5.5 °C. Since the Earth reflects about 28% of incoming sunlight, in the absence of the greenhouse effect the planet's mean temperature would be far lower - about -18 or -19 °C instead of the much higher current mean temperature, about 14 °C.

Global warming, a recent warming of the Earth's surface and lower atmosphere, is believed to be the result of a strengthening of the greenhouse effect mostly due to human-produced increases in atmospheric greenhouse gases.