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Greenhouse gas

Gas in an atmosphere that absorbs and emits radiation within the thermal infrared range / From Wikipedia, the free encyclopedia

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A greenhouse gas (GHG or GhG) is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect.[1] The primary greenhouse gases in Earth's atmosphere are water vapor (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ozone (O3). Without greenhouse gases, the average temperature of Earth's surface would be about −18 °C (0 °F),[2] rather than the present average of 15 °C (59 °F).[3][4][5] The atmospheres of Venus, Mars and Titan also contain greenhouse gases.[6]

The greenhouse effect of solar radiation on the Earth's surface caused by the emission of greenhouse gases
Radiative forcing (warming influence) of different contributors to climate change through 2019, as reported in the Sixth IPCC assessment report.

Human activities since the beginning of the Industrial Revolution (around 1750) have increased the atmospheric concentration of carbon dioxide by over 50%, from 280 ppm in 1750 to 421 ppm in 2022.[7] The last time the atmospheric concentration of carbon dioxide was this high was over 3 million years ago.[8] This increase has occurred despite the absorption of more than half of the emissions by various natural carbon sinks in the carbon cycle.[9][10]

At current greenhouse gas emission rates, temperatures could increase by 2 °C (3.6 °F), which the United Nations' Intergovernmental Panel on Climate Change (IPCC) says is the upper limit to avoid "dangerous" levels, by 2050.[11] The vast majority of anthropogenic carbon dioxide emissions come from combustion of fossil fuels, principally coal, petroleum (including oil) and natural gas, with additional contributions from cement manufacturing, fertilizer production, deforestation and other changes in land use.[12][13][14]