Nascimento Leonardo, Kuramochi Takeshi, Höhne Niklas
NewClimate Institute, Cologne, Germany.
Environmental Systems Analysis Group, Wageningen University & Research, Wageningen, the Netherlands.
Mitig Adapt Strateg Glob Chang. 2022;27(6):39. doi: 10.1007/s11027-022-10018-5. Epub 2022 Jul 14.
Many years passed since the adoption of the Paris Agreement, which invites countries to determine their own contributions to climate change mitigation efforts. The Agreement does not offer a standard to measure progress but relies on a process of periodic stocktakes to inform ambition-raising cycles. To contribute to this process, we compare 2021 greenhouse gas emission projections up to 2030 against equivalent projections prepared back in 2015. Both sets of projections were prepared using the same bottom-up modelling approach that accounts for adopted policies at the time. We find that 2021 projections for the G20 as a group are almost 15% lower (approximately 6 GtCOeq) in 2030 than projected in 2015. Annual emissions grow 1% slower in the coming decade than projected in 2015. This slower growth mostly stems from the adoption of new policies and updated expectations on technology uptake and economic growth. However, around one-quarter of these changes are explained by the effects of the COVID-19 pandemic on short-term emissions and economic forecasts. These factors combined result in substantially lower emission projections for India, the European Union plus the UK (EU27 + UK), the Unites States, Russia, Saudi Arabia, and South Africa. We observe a remarkable change in South African projections that changed from a substantial increase to now a decline, driven in part by the planned phase-out of most of its coal-based power. Emissions in India are projected to grow slower than in 2015 and in Indonesia faster, but emissions per capita in both countries remain below 5 tCOeq in 2030, while those in the EU27 + UK decline faster than expected in 2015 and probably cross the 5 tCOeq threshold before 2030. Projected emissions per capita in Australia, Canada, Saudi Arabia, and the United States are now lower than projected in 2015 but remain above 15 tCOeq in 2030. Although emission projections for the G20 improved since 2015, collectively they still slightly increase until 2030 and remain insufficient to meet the Paris Agreement temperature goals. The G20 must urgently and drastically improve adopted policies and actions to limit the end-of-century warming to 1.5 °C.
The online version contains supplementary material available at 10.1007/s11027-022-10018-5.
自《巴黎协定》通过以来,许多年过去了。该协定邀请各国确定自己对减缓气候变化努力的贡献。该协定没有提供衡量进展的标准,而是依靠定期盘点的过程来为提高目标的周期提供信息。为推动这一进程,我们将2021年至2030年的温室气体排放预测与2015年时编制的同等预测进行了比较。两组预测均采用相同的自下而上建模方法,该方法考虑了当时已采用的政策。我们发现,2021年对二十国集团(G20)整体的预测显示,到2030年其排放量比2015年预测的低近15%(约60亿吨二氧化碳当量)。未来十年的年排放量增长速度比2015年预测的慢1%。这种较慢的增长主要源于新政策的采用以及对技术应用和经济增长的更新预期。然而,这些变化中约四分之一可归因于新冠疫情对短期排放和经济预测的影响。这些因素综合起来导致印度、欧盟加英国(欧盟27国+英国)、美国、俄罗斯、沙特阿拉伯和南非的排放预测大幅降低。我们观察到南非的预测发生了显著变化,从大幅增加变为现在的下降,部分原因是计划逐步淘汰其大部分煤基电力。预计印度的排放量增长速度将比2015年慢,而印度尼西亚的增长速度更快,但到2030年两国的人均排放量仍低于5吨二氧化碳当量,而欧盟27国+英国的人均排放量下降速度比2015年预期的更快,可能在2030年前突破5吨二氧化碳当量的门槛。澳大利亚、加拿大、沙特阿拉伯和美国的预计人均排放量现在低于2015年的预测,但到2030年仍高于15吨二氧化碳当量。尽管自2015年以来G20的排放预测有所改善,但总体上到本世纪末排放量仍会略有增加,仍不足以实现《巴黎协定》的温度目标。G20必须紧急且大幅改进已采用的政策和行动,以将本世纪末的升温限制在1.5摄氏度以内。
在线版本包含可在10.1007/s11027-022-10018-5获取的补充材料。