中国减少一氧化二氮的努力与前景

1.NitrousOxide: The Third Largest Greenhouse Gas inThe World Emissions of nitrous oxide (N₂O), a major GHG,aregaining increasedattention.Datafrom the Global Atmospheric Research EmissionsDatabase (EDGAR)indicates thatglobalN₂Oemissions in 2023reached approximately2.5 billion tons of carbondioxide equivalent (CO2e), accounting for5% of globalGHGemissions. ThismakesN₂O the third largest GHG after carbon dioxide and methane.1Although N₂Oemissionsarerelativelylowercompared to carbon dioxide, it has a strong warmingeffect, with a warming potential of about 273 timesgreater thancarbon dioxideovera100-yearperiod—and long atmospheric lifespan of around 120 years.2The2024globalN₂Obudgetalso reveals thatN₂Oemissions from human activities haveincreased by40% between 1980 and 2020.3In addition, research shows that, withoutadditionalmeasures, N₂O emissions are expected to rise by approximately 30% by2050 compared to 2020.4Therefore, taking early action to reduce N₂O emissions isessential to mitigate climate change. In addition to contributing to global warming,N₂Oemissions 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,N₂Oemissions remain outside its scope. As aresult,N₂Ohas become the primary gases depleting the ozone layer.5The UnitedNations Environment Programme (UNEP) highlighted this issue in its 2022 scientificassessment of ozone depletion.The report found thatN₂Oemissions (using CFC-11equivalent) from human activities between 2016 and 2020 were twice as high asglobal emissions of CFCs in 2020.6Furthermore, theseN₂Oemissions are expectedto delay the ozone layer’s recovery, underscoring the need for targeted mitigationefforts. ReducingN₂O emissions can also offer additional environmental benefits,asnitrogen oxides (NOx), a common air pollutant from stationary sources, contain smallamounts ofN₂O. LoweringN₂Oemissions not only helps with climate mitigation butalso contributes to improving air quality by reducing photochemical smog andminimizing soil acidification. 2.CurrentStatus and Trends ofN₂OEmissions 2.1.GlobalN₂OEmissions:HumanActivitiesDrive theIncrease While natural sources such as soil, oceans, and the atmosphere contribute to globalN₂Oemissions,thesedo not result in significant atmospheric accumulation, asnatural systems can gradually balance them over time.7The current rise inN₂Oemissions is primarily driven by human activities. In2019,agriculture was the largest contributor,responsible for 76%ofanthropogenicN₂O emissions,followed by energy-related activities(10%),industrial processes (8%), and waste management (5%).8 Agriculture N₂Oemissionsprimarilyarisefromagriculturallandandmanuremanagement.Whenfarmers use nitrogen-based fertilizers,N₂O is released into the soil.Additionally,manure from livestock and poultry stored or treated can alsoproduceN₂Othroughnaturalchemicalprocesses. Energy activities Emissions are mainly from the combustion of fossil fuels and biomass. Industrial process Major sources include the production of adipic and nitric acid. Adipic acidis primarily used in nylon and polyurethane. Nitric acid is essential for themanufacture of synthetic fertilizers, pesticides, and rubber. Waste management N₂O emissions mainly come from domestic sewage and industrial wastewatertreatment. 2.2.China’sN₂OEmissions: Agricultureand Industry Are KeyContributors According to the Third Biennial Update Report on Climate Change of the People'sRepublic of China (Figure 2), China'sN₂Oemissions in 2018reached1.915 milliontons, accounting for 5% of thenation'stotal GHG emissions(excluding LULUCF).The largest source wasagriculture(943,000 tonsor49.2%),followed by industrialprocesses (441,000 tons or23%),energy activities (411,000 tons or 21.5%), andwaste management (119,000 tons or 6.2%). Historical data from China’s national greenhouse gas inventory reveals thatN₂Oemissions rose sharply by 36% from 2005 to 2014 but stabilized between 2014 and2018(Figure 1).However,projections indicate that without stronger policyintervention, emissions could continue to rise, potentially reaching between 620and 790 million tons of CO2e by 2050(Figure 3). Source:Teng et al, (2019),9WRI data from Song, R. (2019),10EPA data from USEPA. (2019),11iGDP data is based onEPS model analysis. 3.Progress onN₂OEmissionReductionPolicies 3.1.Progress inGlobalN₂OEmissionsReduction Countries and regions are increasingly taking proactive steps to reduceN₂Oemissions. In theEuropean Union (EU), the Farm to Fork Strategy aims to enhancesoil health and cut nitrogen fertilizer use by 20% by 2030,as part of the Green NewDeal.12Australia is providing financial incentives through the Emissions ReductionFund to encourage businesses and individuals to decreaseN₂O emissions inagriculture .13Since 2013, the EU has included the regulation ofN₂Oemissions fromnitric acid and