Nitrous Oxide Fact Sheet

Nitrous oxide is the world's largest contributor to ozone depletion

Nitrous oxide (N2O) is an atmospheric gas commonly known as laughing gas. Though less abundant than carbon dioxide in the atmosphere, it is 300 times more powerful than carbon dioxide in trapping heat. It also lingers in the atmosphere longer than CO2.

Nitrous oxide is one of the primary greenhouse gases produced by agricultural practices such as applying synthetic fertilizers and livestock manure to grow crops. Combustion from It increased twenty percent over the last 100 years and now accounts for six percent of anthropogenic climate change. Scientists continue to find higher levels of N2O in rivers, soils and the atmosphere than previously believed.

A 2011 study placed nitrous oxide levels in the world’s waterways at three times the amount estimated by the Intergovernmental Panel on Climate Change (IPCC). The study, published in the Proceedings of the National Academy of Sciences, said N20 is mostly created when synthetic fertilizer washes from farms into rivers and streams, undergoes a chemical change, and ends up in the air as nitrous oxide.

Scientists with the International Council for Science (ICSU) found that there is more N2O in the atmosphere than previously estimated by the IPCC. The Council cautioned that increasing corn production for biofuels spells trouble for global N2O levels, in part because corn’s shallow root system makes it an especially “nitrogen-leaky” plant.

Nitrous oxide has been found to be a new culprit in destroying Earth’s protective ozone layer. Researchers at the National Oceanic and Atmospheric Administration (NOAA) reported that the 1987 Montreal Protocol had successfully reduced chlorofluorocarbons (CFCs) in the atmosphere. In an unexpected twist, NOAA found N2O’s impact on ozone levels had increased in response, because chlorofluorocarbons inhibit the ozone-destroying actions of nitrous oxide. The New York Times covered the story.

In California, the Agricultural Sustainability Institute (ASI) at UC Davis will be releasing a California Nitrogen Assessment in 2011 that takes the N2O pulse of the state. The goal is to learn more about how much nitrogen fertilizer is being used and where runoff is escaping, and to share nitrogen use efficiency practices with farmers.