Less frequently addressed in proposed legislation is emission reduction for non-CO 2 greenhouse gases, such as nitrous oxide (N 2 O). However, N 2 O reduction efforts have the potential to mitigate climate change. No new legislation needs to be passed to regulate N 2 O for climate protection and ozone recovery. The five non-CO 2 greenhouse gases regularly monitored but not entirely regulated by EPA (methane, nitrous oxide, hydroflourocarbons, perflourocarbons, and sulfur hexaflouride) accounted for approximately 17% of U.S. greenhouse gas (GHG) emissions in 2009, as measured by total tons of CO 2 equivalent. N 2 O emission reduction could thus play a compelling role in recovery of the ozone layer as well as in greenhouse gas emission reduction. The agriculture sector is the primary anthropogenic source of nitrous oxide. Once released, N 2 O lingers in the atmosphere for decades (its atmospheric lifetime is approximately 114 years) and is 310 times more effective at trapping heat in the atmosphere over a 100-year time frame than carbon dioxide (CO 2 ). Sources of N2O Emissions

Nitrous oxide is emitted from anthropogenic (manmade) and natural sources. Agricultural soil management (e.g., fertilization, application of manure to soils, drainage and cultivation of organic soils) is responsible for more than two-thirds of anthropogenic U.S. N 2 O emissions. In 2009, N 2 O emissions from agricultural soil management totaled more than 200 million metric tons of CO 2 e. Other anthropogenic sources of N 2 O are combustion by mobile sources (cars, trucks, etc. Policy Options for Nitrous Oxide Emission Reduction

Congress has begun to investigate the reduction of non-CO 2 greenhouse gas emissions, including N 2 O emissions, as one strategy to mitigate climate change. Congress could approach N 2 O emissions reduction as part of a comprehensive GHG emission strategy offering economically attractive abatement alternatives to discourage actions leading to climate change. With or without ODP substance listing, Congress may find it useful to incorporate the ozone depletion impacts of N 2 O into its climate change policy proposals both to reduce greenhouse gas emissions and to further ozone recovery achievements.
Gases other than carbon dioxide accounted for approximately 17% of total U.S. greenhouse gas emissions in 2009, yet there has been minimal discussion of these other greenhouse gases in climate and energy legislative initiatives. Reducing emissions from non-carbon dioxide greenhouse gases, such as nitrous oxide (N2O), could deliver short-term climate change mitigation results as part of a comprehensive policy approach to combat climate change.
Nitrous oxide is 310 times more potent than carbon dioxide in its ability to affect the climate; and moreover, results of a recent scientific study indicate that nitrous oxide is currently the leading ozone-depleting substance being emitted. Thus, legislation to restrict nitrous oxide emissions could contribute to both climate change protection and ozone recovery.
The primary human source of nitrous oxide is agricultural soil management, which accounted for more than two-thirds of the N2O emissions reported in 2009 (approximately 205 million metric tons CO2 equivalent). One proposed strategy to lower N2O emissions is more efficient application of synthetic fertilizers. However, further analysis is needed to determine the economic feasibility of this approach as well as techniques to measure and monitor the adoption rate and impact of N2O emission reduction practices for agricultural soil management.
As the 112th Congress considers legislation that would limit greenhouse gas emissions, among the issues being discussed is how to address emissions of non-CO2 greenhouse gases. Whether such emissions should be subject to direct regulation, what role EPA should play using its existing Clean Air Act authority, and what role USDA should play in any N2O reduction scheme are among the issues being discussed. How these issues are resolved will have important implications for agriculture, which has taken a keen interest in climate change legislation.