全球气候变化已成为人类社会所面临的严峻挑战.控制化石燃料排放、发挥陆地生态系统碳汇(下简称陆地碳汇)功能,是人类社会应对气候变化、实现碳中和的基本路径.我国是世界上最大的碳排放国,从全国及省域尺度上系统评估碳排放和陆地碳汇状况,对于我国及各省市制定合理的减排规划、实现碳中和具有重要意义.本研究基于翔实数据,对全国和省域尺度1980～2020年间碳排放量、清洁能源减排量、陆地碳汇进行系统概算,并评估清洁能源和生态系统碳汇在缓解碳排放、实现相对减排中的贡献(简称减排贡献,是表征碳中和水平的测度).在全国尺度上,碳排放量、人均碳排放量均表现出显著增长趋势,但单位GDP碳排放强度显著下降;省域尺度上,多数省份表现出与全国类似的变化趋势,但省际间差异明显.过去40年间我国清洁能源的总体减排贡献不大,但近年减排贡献显著上升,已接近当前碳排放量的20％;省域尺度上,各省的清洁能源开发状况相差悬殊,大多数省份的减排贡献都较为有限.基于实测数据的估算结果表明,1980年代～2010年代间,我国陆地碳汇总量抵消了同期总碳排放的15.1％;虽然陆地碳汇呈显著增长趋势,但由于排放增长更快,导致碳汇抵消比例由1980年代的30.5％下降至2010年代的12.9％.在省域尺度上,各地碳汇大小差异较大:碳汇总量最大的为内蒙古,是碳汇最小的上海的81倍;各省单位面积碳汇变动于0.04～0.68 t C/(公顷年)之间,其中福建最大(0.68 tC/(公顷年)),青海最小(0.04 tC/(公顷年)),全国平均为0.22 tC/(公顷年).本研究建议在未来减排增汇工作中,要重点关注能源利用效率提升,采取分省份、分区域、分批次地实现碳达峰的策略;要进一步发掘各省清洁能源开发潜力;要充分发挥陆地生态系统的碳汇功能,采取"最优生态系统布局、最优物种配置、最优生态系统管理"的"三优"生态系统管理原则,实现碳汇最大化的目的.
Estimation of national and provincial carbon emissions,terrestrial carbon sinks and their relative contribution to emission reductions during 1980～2020
Global climate change,largely caused by anthropogenic carbon(C)emissions,has been one of the most critical challenges for human society.Reducing fossil fuel C emissions,enhancing the production and utilization of clean energy,as well as strengthening the terrestrial C sinks,are basic pathways for climate change mitigation and C neutrality target.To better support the formulation and the achievement of long-term mitigation pathway for China,this study conducted a systematic assessment of fossil fuel C emissions,emission reductions from clean energy usage,and terrestrial ecosystem C sinks at both national and provincial levels during the past four decades(1980～2020).Additionally,it evaluated the contributions of clean energy and terrestrial C sinks in mitigating C emissions and achieving relative emission reductions(referred to as"emission reduction contribution",which can be considered a measure of C neutrality status).The results showed that at the national level,both total and per capita C emission increased significantly from 1980 to 2020,while C intensity per unit of GDP witnessed a notable decrease.Similar temporal trends were found in most provinces,though variations in the patterns of emission and relevant characteristics were evident among regions.Following the rapid deployment of clean energy,it has contributed to an emission reduction by approximately to～20％of national total C emissions in 2020,while the contribution differed substantially by province due to differences in clean energy availability.China's terrestrial ecosystems functioned as a sizable and increasing C sink,offsetting 15.1％of anthropogenic C emissions during 1980s～2010s.However,the emission reduction contribution of terrestrial ecosystem C sinks(i.e.,the ratio of C sinks to C emissions)declined from 30.5％in the 1980s to 12.9％in the 2010s,mainly due to faster growth of C emission compared to the enhancement of C sinks.The size of terrestrial ecosystem C sinks varied substantially among provinces,with the largest sink in Inner Mongolia and the smallest in Shanghai.The average C sink per unit area is 0.22 t C/(ha yr)during 1980～2020 at national level,with provincial values ranging between 0.04(Qinghai)～0.68(Fujian)t C/(ha yr).Our results highlight the following strategic focus areas for formulating long-term mitigation efforts.Improving energy efficiency should be prioritized across the country.Meanwhile,efforts to further explore clean energy potential and sustainable deployment should be strengthened in all provinces to achieve energy system decarbonization.Provincial strategies should also accommodate differing peak C emission timelines.Furthermore,the"three-optimal principles"for ecosystems management—optimizing vegetation goals by region,optimizing species combinations for a given site,and optimizing management for ecosystems based on their characteristics—are crucial to realizing the full potential in China's terrestrial C sequestration.
万方数据
