基于各国NDC/INDC目标的全球减排不确定性研究

基于各国提交的165份国家自主贡献文件,以其中提出的减排目标为基准,尽可能充分地考虑了减排目标的范围不确定性、不同经济情景带来的碳强度减排目标不确定性、减排气体种类边界差异、碳排放达峰约束等因素,并通过蒙特卡洛模拟的方法对全球、各区域和主要经济体的温室气体排放总量、不确定度及其来源进行了定量分析。结果表明,到2030年全球温室气体排放总量将达到62.69 Gt CO₂当量,其90%信度的置信区间为53.17~74.26 Gt CO₂当量;由于未来经济总量预期不确定对排放量的影响最显著,因此,不同地区之间不确定性来源差异较大。同时,基于到2050年排放总量比2010年下降40%~70%的2℃目标排放情景,2030—2050年全球温室气体排放年均需要下降5.0% %。为了尽可能减小全球温室气体排放预期目标的不确定性和继续实现2℃目标,各国在进行自主贡献文件更新时进一步提出统计边界更为明确和统一且更有雄心的减排目标将是第一次全球盘点继续解决的重点问题。

Estimation of uncertainty based on emission reduction targets in NDC/INDCs

Based on the 165 Nationally Determined Contributions/Intended Nationally Determined Contributions (NDC/INDCs) submitted by countries, the emission reduction targets proposed in NDC/INDCs were taken as the benchmark in this paper. Some factors were considered including the uncertainty of the scope of the emission reduction target, the uncertainty of the carbon intensity reduction target derived from economic scenarios, boundary differences of emission reduction gas type and carbon emission peak constraints, and Monte Carlo simulation were used to quantitatively analyze GHG emissions, uncertainties and their sources of global, regional, and major economies. The results show that by 2030, the total global GHG emissions will reach 62.69 Gt CO₂e, with a 90% confidence interval of 53.17-74.26 Gt CO₂e; since the uncertainty of expected future economy has the most significant impact on emissions, the sources of uncertainty vary greatly among regions. Meanwhile, based on the 2℃ target emission scenario where total emissions by 2050 are 40%-70% lower than in 2010, global GHG emissions need to be reduced by 5.0% % annually from 2030 to 2050. In order to minimize the uncertainty of the global GHG emissions target and continue to work towards the completion of the 2℃ target, countries have to further propose clearer and unified statistical boundaries and more ambitious emission reduction targets when updating their NDCs during the first global stock take.