Air quality co-benefits of ratcheting up the NDCs

Sebastian Rauner,Gunnar Luderer,Jérôme Hilaire,Jessica Strefler,David Klein

doi:10.1007/s10584-020-02699-1

Abstract

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.

Highlights

As acknowledged through the Paris Agreement, climate change will require international collective action to limit the global mean temperature increase to well below 2 ◦C above preindustrial levels
Recent literature on the nexus of climate change and air pollution analyzed the effects of different climate and air pollution policy scenarios in terms of reduced pollution concentration levels (Rao et al 2016), estimated the social costs of air pollution to be comparable with the mitigation cost (West et al 2013; Vandyck et al 2018), analyzed the health co-benefits under different distributions of climate change abatement efforts (Rafaj et al 2012; Markandya et al 2018), and focused on regional characteristics (Xie et al 2018; Li et al 2018)
While Europe is phasing out coal already in the short term under the current Nationally Determined Contributions (NDC), there is only a marginal effect on the primary energy mix of China and India compared with the reference until 2030

Summary

Introduction

As acknowledged through the Paris Agreement, climate change will require international collective action to limit the global mean temperature increase to well below 2 ◦C above preindustrial levels. Air pollution has a multitude of negative impacts on the environment (e.g., acid rain, eutrophication) and the economy (e.g., the decrease of capital value, productivity loss from the workforce, crop yield losses), the most relevant in terms of social cost are effects on human health mainly via cardiovascular disease, and others we are just beginning to understand. In contrast to existing literature, we assess different climate policies in combination with air pollution control scenarios with a special focus on the congruent implementation of the spatially explicit socioeconomic features of the scenarios in all of the modeling steps This is especially important since socioeconomic trends play a crucial role in the development of the Energy-Economy-Climate nexus and for the health impacts of air pollution. We use a common Shared Socioeconomic Pathways (SSP) (O’Neill et al 2017) scenario, corresponding to the SSP2 pathway

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