Greenhouse gas

A gas that absorbs and emits infrared radiation, contributing to warming of a planet’s surface and lower atmosphere. Its effect depends on its concentration, lifetime, and interaction with radiation.

Greenhouse effect: Warming of a planet’s surface and lower atmosphere caused when atmospheric constituents absorb and emit outgoing infrared radiation. Greenhouse gases produce this radiative warming by intercepting infrared energy leaving the surface.
Carbon dioxide: A long-lived atmospheric gas produced by respiration, combustion, and other carbon-cycle processes. It is the largest human-caused contributor to long-term greenhouse-gas forcing.
Global warming potential: A measure comparing the integrated warming influence of a gas with that of carbon dioxide over a specified period. It allows gases with different lifetimes and radiative effects to be compared.
Climate change: Long-term shifts in climate patterns, including changes in temperature, precipitation, and extreme events. Rising greenhouse-gas concentrations are the dominant human influence on recent global climate change.
Aerosol: A suspension of tiny solid particles or liquid droplets in a gas, including the atmosphere. Aerosols often scatter sunlight or alter clouds, unlike gases that absorb and emit infrared radiation.
Infrared spectroscopy: A technique that identifies and measures substances by their interaction with infrared radiation. Molecular absorption spectra reveal which wavelengths each greenhouse gas captures.
Methane: A potent, relatively short-lived greenhouse gas emitted by natural processes and human activities. Its strong near-term warming effect contrasts with its shorter atmospheric lifetime than carbon dioxide.
Carbon dioxide equivalent: A unit expressing the warming impact of different greenhouse gases as an equivalent amount of carbon dioxide. Inventories use it to combine emissions of gases with different warming potentials.
Ocean acidification: The decline in ocean pH caused primarily by seawater absorbing atmospheric carbon dioxide. Carbon dioxide affects oceans chemically as well as by trapping heat in the atmosphere.
Ozone-depleting substance: A chemical that destroys stratospheric ozone through atmospheric reactions. Some ozone-depleting substances also trap infrared radiation, but ozone destruction is a distinct effect.

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