Greenhouse Effect

The greenhouse effect is the warming of a planet’s surface caused by atmospheric gases that absorb and re-emit outgoing longwave (infrared) radiation while remaining largely transparent to incoming solar shortwave radiation. Water vapor, carbon dioxide, methane, nitrous oxide, and ozone trap part of the surface emission and re-radiate it downward, raising the surface temperature above the radiative-equilibrium value. Without it Earth’s mean surface temperature would be near 255 K rather than the observed 288 K. Rising CO2 strengthens the effect and adds radiative forcing at the top of the atmosphere; the ocean absorbs most of that excess heat, with measurable warming of the upper layers.