Which greenhouse gas has a global warming potential about 300 times that of CO2?

Nitrous oxide has a global warming potential of about 300 times that of carbon dioxide over a 100-year comparison period. Its chemical formula is N₂O, and it is a long-lived greenhouse gas as well as an ozone-depleting substance.

Global warming potential compares the heat absorbed by a given mass of a gas with the heat absorbed by the same mass of CO₂ over a specified time horizon. The exact figure depends on the assessment and timescale: recent IPCC values commonly give N₂O a 100-year GWP of 273, while older estimates and rounded explanations often state 265 or approximately 300.

Nitrous oxide is released naturally by soils and oceans, but human emissions have grown substantially. Agriculture is the leading source, particularly the use of synthetic nitrogen fertilisers and the management of manure. Fossil-fuel combustion and some industrial processes also contribute.

N₂O is far less abundant than carbon dioxide, so its total contribution is smaller. Its high potency and atmospheric lifetime—roughly 116 years—make reducing emissions important for both climate protection and ozone-layer recovery.