Abating industrial nitrous oxide emissions in the United States: legal, economic and scientific dimensions

US and global climate policy continues to largely ignore nitrous oxide (N2O), despite it being responsible for 10% of net global warming since the Industrial Revolution and the largest remaining threat to the stratospheric ozone layer. Though agriculture is the dominant anthropogenic driver, industrial sources – primarily nitric and adipic acid production – are an important opportunity for rapid and cost-effective action. Here we analyse the legal and environmental dimensions of ambitious N2O abatement from nitric and adipic acid production in the United States. With 31 nitric acid and 2 adipic acid production facilities, ambitious abatement could reduce N2O emissions by approximately 330–700 kt N2O over 20 years, avoiding the equivalent of 7–14 kt ODP and 90–190 million tons CO2. This would avoid $12–61 billion in climate damages and $0.7–2.8 billion in stratospheric ozone damages, including 2900–5800 skin cancer cases. Meanwhile, abatement would cost $25–$221 million – 50–2100 times less-than the potential societal benefits. The US Environmental Protection Agency has the legal authority under the Clean Air Act to regulate N2O emissions from nitric and adipic acid production. Most notably, Section 615 provides broad legal authority to the EPA to regulate any substance, process, practice or activity deemed to be a threat to the stratospheric ozone layer. EPA has also historically used Section 111 to regulate greenhouse gas emissions from stationary sources. Both regulatory avenues could potentially provide more comprehensive and durable emissions reductions than currently available voluntary carbon market initiatives, although the future of the Section 111 programme remains uncertain following the repeal of the 2009 GHG endangerment finding. As we approach a variety of environmental tipping points, it is important to assess all regulatory options for delivering cost-effective emissions reductions. Abating N2O emissions from nitric and adipic production using existing regulatory authority would provide significant ozone and climate benefits, while providing a springboard for broader N2O abatement moving forward.Key policy insights The Clean Air Act provides the legal authority for the U.S. Environmental Protection Agency to abate N2O emissions without new legislation.