Nitrous oxide
A long-lived greenhouse gas with the formula N₂O, associated with natural processes and activities such as fertiliser use.
Example
Soil microbes can produce it when nitrogen enters agricultural systems.
The catch
It is chemically different from nitrogen dioxide, an air pollutant.
Related terms
Greenhouse gas, Albedo, Atmospheric lifetime, Carbon budget, Carbon dioxide, Climate change
In more depth
Nitrous oxide, explained.
Most human-caused nitrous oxide comes from agriculture, where soils release it when fertiliser or manure supplies more nitrogen than crops can use. Applying the right amount at the right time and place is the main way to cut it. Industry contributes too, mainly through plants making nitric and adipic acid, where catalysts can destroy much of the gas at low cost.
Tonne for tonne it warms far more than CO₂, which gives small quantities real influence on a farm footprint. It outlasts methane in the atmosphere by a wide margin, so cuts pay off slowly and the benefit lasts. It also depletes the stratospheric ozone layer. Field emissions swing with rainfall, temperature and soil type, and inventories that rely on a default emission factor carry wide measurement uncertainty as a result.