image: Accessibility of future climate targets and air quality improvements over China. Estimates of future CO2 emissions and PM2.5 exposure under different mitigation pathways in 2030 (A) and 2060 (B). The circle and triangle markers represent the 90th percentile of PM2.5 exposure and the population-weighted PM2.5 concentration, respectively. Labeled percentage numbers refer to the fossil fuel fraction in the primary energy mix. The horizontal red dashed lines represent the National Ambient Air Quality Standards (i.e. 35 μg/m3) and WHO Air Quality Guideline (i.e. 10 μg/m3). Light blue shaded portions are the ranges of published and simulated results on China's anthropogenic CO2 emission peak under the NDC target (in panel A) and the projected natural carbon sink in 2060 under low radiation forcing scenarios (in panel B), and the dark blue dashed line represents the mean value of collected data.
China's clean air policies have substantially reduced PM2.5 air pollution in recent years. Yet >99% of Chinese population is still exposed to PM2.5 concentrations in excess of the World Health Organization (WHO) Air Quality Guidelines of 10 μg/m3. Climate actions targeting to reduce fossil fuel consumption also have substantial air quality benefits. The announcement of ambitious climate commitment to achieve carbon neutrality by 2060 may fuel the power to long-term air quality improvement in China.
Combining Global/China's climate mitigation pathways (i.e. global 2°C- and 1.5°C-pathways, NDC pledges, and carbon neutrality goals) and local clean air policies, Chinese energy system, anthropogenic emissions and PM2.5 air quality pathways from 2015 to 2060 are assessed. If the government improves the source treatment--promote the renewable energy fraction, push the production peaks of high consumption industries (e.g., iron, steel, cement), accelerate the phasing out of scattered coal; meanwhile continue to promote the in-depth end-of-pipe control in high-polluted industries, diesel-fueled vehicles and engines, and VOC-related industries, China would meet the NDC climate target in 2030, as well as mitigate the national population-weighted PM2.5 concentrations to ~28 μg/m3, achieving the national air quality standards.
However, the benefits of end-of-pipe control reductions are mostly exhausted by 2030, and reducing PM2.5 exposure of the majority of the Chinese population to below 10 μg/m3 by 2060 will likely require more ambitious climate mitigation efforts such as China's carbon neutrality goals and global 1.5°C-pathways. As the solution, by 2060, China will complete the transformation of low-carbon energy, with the dominate role of renewable energy (i.e. the renewable energy power generation would account for more than 70%, the fraction of coal would be less than 15% in industry sector, electricity and hydrogen vehicles would account higher than 60%). Such in-depth energy transition would lower China's carbon emissions by 90%. As a result, the average annual exposure level of PM2.5 will be around 8 μg/m3, lower than the WHO guideline and the air pollution problem has been fundamentally solved.
Cheng et al. proposes practical strategies to address both air pollution and GHGs emissions in the near-term, in which co-control measures focusing on co-emitted sources (i.e. fossil fuel consumption), co-management mechanism on PM2.5 and O3 pollution, and co-development plan on low carbon economy and clean energy transition are prioritized. China's future clean air pathways should transform from end-of-pipe control to energy and economic system optimization. Meanwhile, China should proactively promote the air quality standards to gradually integrate with the relevant WHO standards 10 μg/m3 as a new long-term goal, to accelerate the implementation of carbon neutrality strategy.