21 November 2013: Increases in nitrous oxide emissions could exacerbate climate change and undermine ozone layer recovery, according to a report by the UN Environment Programme (UNEP). The report also stresses it is possible to decrease nitrous oxide emissions, resulting in climate, economic, environmental and human benefits of approximately US$160 billon annually.

Nitrous oxide, commonly known as ‘laughing gas’, is the most important ozone depleting substance (ODS) and the third most potent greenhouse gas (GHG), according to UNEP. Nitrous oxide’s radiative properties and 120-year atmospheric lifetime mean that it has a disproportionate impact on global warming. Further, unlike chlorofluorocarbons (CFCs) and other ODS, nitrous oxide is not controlled by the Montreal Protocol on Substances that Deplete the Ozone Layer and its emissions are expected to almost double by 2050.

Achim Steiner, UNEP Executive Director, said addressing nitrous oxide emissions offers an “opportunity to keep the world under a two degree Celsius temperature rise” and achieve co-benefits. Drawing down nitrous oxide can help, inter alia: secure gains in ozone layer recovery made by the Montreal Protocol; narrow the emissions gap by approximately 8%; and increase well-being through the green economy.

The UNEP report, titled ‘Drawing Down N2O to Protect Climate and the Ozone Layer,’ analyzes mitigation scenarios, ranging from business as usual, where levels of nitrous oxide could increase 83% between 2005 and 2050, to concerted mitigation, where nitrous oxide levels could be 22% lower in 2050 than in 2005.

It provides mitigation options in the agriculture, aquaculture, biomass, industry and wastewater sectors. To reduce agricultural emissions, which account for two-thirds of anthropogenic nitrous oxide emissions, the report recommends: boosting nitrogen use efficiency during animal production and crop cultivation; reducing meat consumption; and reducing food loss and waste. It also recommends, inter alia: installing emissions control equipment in facilities that produce adipic acid and nitric acid, which account for 5% of nitrous oxide emissions; implementing prescribed burning; improving the combustion and fuel efficiency of stoves; and recycling nutrients in wastewater as fertilizer.

The report identifies capacity building, cost, lack of training and knowledge and technology transfer as barriers to reducing nitrous oxide. It recommends financial, regulatory and voluntary approaches to overcome these barriers, including: setting targets for nitrous oxide emissions reduction and nitrogen use efficiency and tracking progress; putting a price tag on nitrogen pollution; removing subsidies; and providing incentives for good nutrient management practices, especially for farmers in developing countries. [UNEP Press Release] [Publication: Drawing Down N2O to Protect Climate and the Ozone Layer]