绿色创新发展研究院Policy Brief SeriesNitrous OxideReduction Efforts andProspects in ChinaNov/20241.Nitrous Oxide:The Third Largest Greenhouse Gas inThe WorldEmissions of nitrous oxide (N2O),a major GHG,are gaining increased attention.Datafrom the Global Atmospheric Research Emissions Database (EDGAR)indicates thatglobal N2O emissions in 2023 reached approximately 2.5 billion tons of carbondioxide equivalent (CO2e),accounting for 5%of global GHG emissions.This makesN2O the third largest GHG after carbon dioxide and methane.1 Although N2Oemissions are relatively lower compared to carbon dioxide,it has a strong warmingeffect,with a warming potential of about 273 times greater than carbon dioxide overa 100-year period-and long atmospheric lifespan of around 120 years.2 The 2024global N2o budget also reveals that N2O emissions from human activities haveincreased by 40%between 1980 and 2020.3 In addition,research shows that,withoutadditional measures.N2O emissions are expected to rise by approximately 30%by2050 compared to 2020.4 Therefore,taking early action to reduce N2O emissions isessential to mitigate climate change.In addition to contributing to global warming.N2O emissions significantly depletethe ozone layer,increasing human exposure to harmful radiation.While the MontrealProtocol has made substantial progress in restoring the ozone layer by regulatingmajor ozone-depleting substances,N2O emissions remain outside its scope.As aresult,N2O has become the primary gases depleting the ozone layer.5 The UnitedNations Environment Programme(UNEP)highlighted this issue in its 2022 scientificassessment of ozone depletion.The report found that N2O emissions (using CFC-11equivalent)from human activities between 2016 and 2020 were twice as high asglobal emissions of CFCs in 2020.6 Furthermore,these N2O emissions are expectedto delay the ozone layer's recovery,underscoring the need for targeted mitigationefforts.1Crippa,M.,Guizzardi,D.,Pagani,F.,Banja,M..Muntean,M..Schaaf,E.,Monforti-Ferrario,F.,Becker,W.E..Quadrelli,R..Risquez Martin.A..Taghavi-Moharamli,P.,Koykka,J.,Grassi,G.,Rossi,S.,Melo,J.,Oom,D.,Branco,A.,San-Miguel,J.,MancaG.,Pisoni,E.,Vignati,E.,Pekar,F.(2024).GHG emissions of all world countries.Publications Office of the European Un ion.https:/dol.org/10.2760/40028972 The GWP values used in the IPCC Sixth Assessment Report are used here3 Tian,H.,Pan,N.,Thompson,R.L.,Canadell,J.G.,Suntharalingam,P.,Regnier,P.,..&Zhu,Q.(2023).Global nitrous oxidebudget 1980-2020.Earth System Science Data Discussions,2023.1-98.Valerie Volcovici.(October 31,2024).World will miss Paris climate target as nitrous oxide rises,report says.Reutershttps://www.reuters.com/business/environment/world-will-miss-paris-climate-target-nitrous-oxide-rises-report-says-2024-10-31/5 Alcamo,J.,Bouwman,L.(2013).Drawing down NaO to protect climate and the ozone layer.United Nations EnvironmentUNEP.(2023.Scientific Assessment of theOzoneLayerDepletion:2022https://ozone.unep.org/system/files/documents/Scie ntific-Assessment-of-Ozone-Depletion-2022.pdf