Energy > Climate Change
December 2021
Nitrous oxide - long-lasting and powerful
This article is the tenth in a series focused on the causes and consequences of a warming planet
Nitrous oxide, also known as laughing gas, is a colorless and non-flammable gas with a slightly sweet odor and taste. It is used in surgery and dentistry. 
It is a powerful and long-lasting greenhouse gas. Atmospheric nitrous oxide captures 265-298 times more heat per unit of mass than carbon dioxide according to the EPA. Also, nitrous oxide emitted today will remain in the atmosphere for an estimated 114 years (compared to 12 years for methane and hundreds of years for carbon dioxide).
Although nitrous oxide emissions occur naturally, about 40% are caused by human activity. About 75% of the human caused emissions occur when nitrogen fertilizer is applied to the soil.
Recent research at Iowa State University shows that the climate warming effects of nitrous oxide emissions from local corn and soybean soils are two-fold greater than the climate cooling that might be achieved by increasing soil carbon storage with common agricultural practices.
ISU’s Steven Hall said "storing carbon in agricultural soils is a valuable tactic to mitigate climate change, but the new research indicates any such policies should first take into account nitrous oxide emissions. Failure to do so could result in policies that are much less effective in addressing climate change."
Nitrous oxide emissions can be reduced by using less nitrogen-based fertilizer and applying fertilizer more efficiently. New products known as enhanced efficiency fertilizers, as well as the application of biochar to fields, might also help to limit nitrous oxide emissions.
An additional 5% is emitted as a result of how manure is managed. If manure doesn’t have access to oxygen, it can be converted to nitrous oxide. Emissions can also occur if manure is over applied to cropland.
Surprisingly, significant nitrous oxide emissions are occurring from the melting of permafrost in the Arctic.
Nitrous oxide poses another threat. When in the atmosphere, it is exposed to sunlight and oxygen and converted to nitrogen oxides. These oxides can damage the ozone layer which protects us from ultraviolet radiation.
Luckily, the actual level of nitrous oxide emissions is relatively small. When its potency is adjusted to a carbon dioxide equivalent, nitrous oxide makes up about 6% of US greenhouse gas emissions. Nevertheless, nitrous oxide is a significant contributor to climate change.
See the Ag Decision Maker website for more from this series.
Don Hofstrand, retired extension agricultural business specialist, agdm@iastate.edu
Reviewed by Dr. Eugene Takle, retired professor emeritus Iowa State University
