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The current nationally determined contributions, pledged by the countries under the Paris Agreement, are far from limiting climate change to below 2 ∘C temperature increase by the end of the century. The necessary ratcheting up of climate policy is projected to come with a wide array of additional benefits, in particular a reduction of today's 4.5 million annual premature deaths due to poor air quality. This paper therefore addresses the question how climate policy and air pollution–related health impacts interplay until 2050 by developing a comprehensive global modeling framework along the cause and effect chain of air pollution–induced social costs. We find that ratcheting up climate policy to a 2 ∘ compliant pathway results in welfare benefits through reduced air pollution that are larger than mitigation costs, even with avoided climate change damages neglected. The regional analysis demonstrates that the 2 ∘C pathway is therefore, from a social cost perspective, a "no-regret option" in the global aggregate, but in particular for China and India due to high air quality benefits, and also for developed regions due to net negative mitigation costs. Energy and resource exporting regions, on the other hand, face higher mitigation cost than benefits. Our analysis further shows that the result of higher health benefits than mitigation costs is robust across various air pollution control scenarios. However, although climate mitigation results in substantial air pollution emission reductions overall, we find significant remaining emissions in the transport and industry sectors even in a 2 ∘C world. We therefore call for further research in how to optimally exploit climate policy and air pollution control, deriving climate change mitigation pathways that maximize co-benefits. [ABSTRACT FROM AUTHOR]

Two emerging policy instruments, carbon pricing and green investments, highlight a complementary relationship between climate mitigation and economic growth. As such, they both advance climate policy differently from command-and-control methods. The central government in China has announced a vision of promoting the two emerging instruments; however, there may be a gap between the central government's vision and local governments' practice. This study measured the application of the three instruments (command-and-control, carbon pricing, and green investments) at the city-level, and described the trends in instrument use from 2011 to 2019. The overall evolution was as follows. Local governments adopted diversified instruments, including rapid but not widely developed carbon pricing, and maintained the command-and-control method. The evolution was different in cities that emphasized the co-benefits of climate and air pollution control; this reflected a binary instrument approach that included the development of both command-and-control and green investment methods. The results identified notable gaps in the application of the green investment method between central and local governments; however, in cities that emphasize co-benefits, the efforts to bridge central–local gaps should mainly focus on the carbon pricing method. [ABSTRACT FROM AUTHOR]