This is a list of the most influential long-lived, well-mixed

greenhouse gas A greenhouse gas (GHG or GhG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse ...

es, along with their tropospheric concentrations and direct

radiative forcing Radiative forcing (or climate forcing) is the change in energy flux in the atmosphere caused by natural or anthropogenic factors of climate change as measured by watts / metre2. It is a scientific concept used to quantify and compare the external ...

s, as identified by the

Intergovernmental Panel on Climate Change The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations. Its job is to advance scientific knowledge about climate change caused by human activities. The World Meteorological Organization (WMO) a ...

(IPCC). Abundances of these

trace gases Trace gases are gases that are present in small amounts within an environment such as a planet's atmosphere. Trace gases in Earth's atmosphere are gases other than nitrogen (78.1%), oxygen (20.9%), and argon (0.934%) which, in combination, make u ...

are regularly measured by atmospheric scientists from samples collected throughout the world. Since the 1980s, their forcing contributions (relative to year 1750) are also estimated with high accuracy using IPCC-recommended expressions derived from

radiative transfer model An atmospheric radiative transfer model, code, or simulator calculates radiative transfer of electromagnetic radiation through a planetary atmosphere. Methods At the core of a radiative transfer model lies the radiative transfer equation that ...

s. This list excludes: *

water vapor (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapor, water vapour or aqueous vapor is the gaseous pha ...

which is responsible overall for about half of all atmospheric gas forcing. Water vapor and

clouds In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may com ...

are more dynamic atmospheric constituents and contribute strong

climate change feedback Climate change feedbacks are important in the understanding of global warming because feedback processes amplify or diminish the effect of each climate forcing, and so play an important part in determining the climate sensitivity and future clim ...

influences. * other short-lived gases (e.g.

carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

NOx In atmospheric chemistry, is shorthand for nitric oxide () and nitrogen dioxide (), the nitrogen oxides that are most relevant for air pollution. These gases contribute to the formation of smog and acid rain, as well as affecting tropos ...

) and

aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be natural or Human impact on the environment, anthropogenic. Examples of natural aerosols are fog o ...

s (e.g.

mineral dust Mineral dust is atmospheric aerosol originated from the suspension of minerals constituting the soil, composed of various oxides and carbonates. Human activities lead to 30% of the airborne dust load in the atmosphere. The Sahara Desert is th ...

black carbon Chemically, black carbon (BC) is a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter). Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion of fossil fue ...

) that also vary more strongly over location and time.

Ozone Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...

has warming influences comparable to

nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has a ...

and CFCs, and is longer lived and more abundant in the

stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air ...

than in the

troposphere The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From ...

. * many

refrigerants A refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are heavily regulated due ...

and other

halogenated In chemistry, halogenation is a chemical reaction that entails the introduction of one or more halogens into a compound. Halide-containing compounds are pervasive, making this type of transformation important, e.g. in the production of polyme ...

gases that have been mass-produced in smaller quantities. Most are long-lived and well-mixed. Some are also listed in Appendix 8A of the 2013 IPCC Assessment Report. and Annex III of the 2021 IPCC WG1 Report * oxygen, nitrogen, argon, and other gases that are less influenced by human activity and interact relatively little with Earth's

thermal radiation Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) is ...

Combined Summary from IPCC Assessment Reports (TAR, AR4, AR5, AR6)

Mole fraction In chemistry, the mole fraction or molar fraction (''xi'' or ) is defined as unit of the amount of a constituent (expressed in moles), ''ni'', divided by the total amount of all constituents in a mixture (also expressed in moles), ''n''tot. This ex ...

s: ''μmol/mol = ppm = parts per million (10⁶); nmol/mol = ppb = parts per billion (10⁹); pmol/mol = ppt = parts per trillion (10¹²).'' The IPCC states that ''"no single atmospheric lifetime can be given"'' for CO₂. This is mostly due to the rapid growth and cumulative magnitude of the disturbances to Earth's

carbon cycle The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and Earth's atmosphere, atmosphere of the Earth. Carbon is the main component of biological compounds as well as ...

by the geologic extraction and burning of fossil carbon. As of year 2014, fossil CO₂ emitted as a theoretical 10 to 100 GtC pulse on top of the existing atmospheric concentration was expected to be 50% removed by land vegetation and ocean sinks in less than about a century, as based on the projections of coupled models referenced in the AR5 assessment. A substantial fraction (20-35%) was also projected to remain in the atmosphere for centuries to millennia, where fractional persistence increases with pulse size.
Values are relative to year 1750. AR6 reports the '' effective radiative forcing'' which includes effects of rapid adjustments in the atmosphere and at the surface.

Gases from IPCC Fourth Assessment Report

The following table has its sources in Chapter 2, p. 141, Table 2.1. of the IPCC Fourth Assessment Report, Climate Change 2007 (AR4), Working Group 1 Report, The Physical Science Basis.

Gases from IPCC Third Assessment Report

The following table has its sources in Chapter 6, p. 358, Table 6.1. of the IPCC Third Assessment Report, Climate Change 2001 (TAR), Working Group 1, The Scientific Basis.

Gases relevant to radiative forcing only

Gases relevant to radiative forcing and ozone depletion

References