“双碳”目标下气候变化风险的预估:从全球到区域

Projection of climate change risk under carbon peaking and carbon neutrality goals:From global level to regional level

借助国际耦合模式比较计划第6阶段(CMIP6)模式模拟结果,基于信噪比(SNR)方法系统评估了“双碳”目标下和更高排放情景下气候变化风险的差异。根据不同的SNR阈值,将气候变化风险量化为“不寻常”(SNR≥1)、“不熟悉”(SNR≥2)和“不可知”(SNR≥3)3种程度。从全球角度来说,在近期未来,各排放情景下CO_(2)排放差异较小,因此“双碳”目标下将与更高排放情景几乎同时面临“不寻常”程度的气候变化风险;而在由CO_(2)排放主导气温变化的中期和远期未来,“双碳”政策将使“不熟悉”或“不可知”程度的气候变化风险比更高排放情景晚数十年到来甚至不会到来,并且使暴露在“不熟悉”或“不可知”程度的气候变化风险下的地表面积比例相较更高排放情景降低30%~60%。区域上,“双碳”目标下,由于近期未来与更高排放情景下气溶胶(AA)排放区域差异显著,不同区域面临“不寻常”程度的气温变化风险的时间与更高排放情景差异较大。因此,结合区域发展特点制定更为合理的CO_(2)和AA协同减排政策对于应对气候变化风险意义重大。

To mitigate the negative impacts of global warming,international community has issued policies to accomplish carbon emission peak and carbon neutrality by 2030s and mid-21st century,respectively.Using projections from the Coupled Model Intercomparison Project Phase 6,this study compares differences of future climate change risks between under carbon peaking and carbon neutrality goals and under higher scenarios based on the signal-to-noise(SNR)method.By the level of climate change risks,the respective climate conditions can be sorted as"unusual"(SNR≥1),"unfamiliar"(SNR≥2)and"unknown"(SNR≥3).Under the low emission scenario,in the near-term future most regions of the earth will face"unusual"climate conditions,nearly simultaneously comparable with higher scenarios due to minor dfferences in CO_(2),emissions between different scenarios,except in some regions where reductions of aerosol emissions will dominate on the local surface air temperature(SAT)change.However,in the mid-term and long-term future,for the fast decrease in CO_(2),emission under carbon emission peaking and neutrality goals,almost all the globe will be exposed to an"unfamiliar"or"unusual"climate condition several decades later even beyond 2100 than under higher scenarios.In addition,mitigation will make the percentage of surface area exposed to higher climate change risks 30~60%lower than those under higher emission scenarios.Therefore,decision-makers should attach more importance to the climate penalty induced by decreased aerosols and take regional characteristics of climate change into consideration for developing more effective adaptation and mitigation strategies.