空气污染-气候相互作用:IPCC AR6的结论解读

Assessment of air quality-climate interactions in IPCC AR6

摘要:

本文解读最近发布的政府间气候变化专门委员会（Intergovernmental Panel on Climate Change，IPCC）第六次气候变化评估报告（Sixth Assessment Report，AR6）关于空气污染-气候相互作用的主要新结论。在大气污染物的气候效应方面，AR6估算了大气污染物或其前体物排放变化导致的有效辐射强迫值（Effective Radiative Forcing，ERF），对评估大气污染治理可能产生的气候效应具有启示性意义。AR6也估算出1750—2019年间人为强迫导致的全球平均地表温度（Global mean Surface Air Temperature，GSAT）变化为1.29（0.99～1.65）℃，其中，均匀混合温室气体、臭氧、气溶胶导致的温度变化分别为1.58（1.17～2.17）℃、0.23（0.11～0.39）℃、-0.50（-0.22～-0.96）℃。气溶胶历史变化的气候效应中，起决定性作用的是由SO₂排放变化通过气溶胶-云相互作用所产生的ERF （高信度），从而部分抵消了人为排放温室气体所引起的变暖（高信度）。在气候变化影响大气污染物方面，AR6首次评估获得了地表臭氧浓度对温度的敏感性，在偏远地区为-0.2 ～-2 nL·L^-1·℃^-1、在污染区为0.2 ～2 nL·L^-1·℃^-1。在大多数陆地区域，关于气候变化是增加还是减少PM_2.5，目前模式结果结论的一致性较低。

Abstract:

This article introduces the new advances in air quality-climate interactions in the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC).AR6 presented emission-based estimates of the effective radiative forcing (ERF) of major air pollutants or their precursors, which have important implications for understanding the climatic effects of air pollution control measures.AR6 quantified the changes in global mean surface air temperature (GSAT) by anthropogenic emissions.Over 1750-2019, anthropogenic ERF was estimated to lead to change in GSAT by 1.29 (0.99-1.65)℃, in which changes in well-mixed greenhouse gases, O₃, and aerosols contributed 1.58 (1.17-2.17)℃、0.23 (0.11-0.39)℃、-0.50 (-0.22——0.96)℃, respectively.Changes in emissions of SO₂ since 1750 have made a dominant contribution to the effective radiation forcing (ERF) of aerosols through aerosol-cloud interactions (high confidence), which partially offset the warming caused by anthropogenic emissions of greenhouse gases (high confidence).AR6 assessed for the first time the sensitivity of surface ozone concentration to temperature, which is -0.2——2 nL·L^-1·℃^-1 in remote areas and 0.2-2 nL·L^-1·℃^-1 in polluted regions.With respect to the impact of climate change on PM_2.5, model results show low consistency about wheather climate change increases or decreases PM_2.5.