Short-term health co-benefits of existing climate policies: the need for more ambitious and integrated policy action

Abstract

Climate change and air pollution are two interconnected major risks for human health.1Romanello M Di Napoli C Drummond P et al.The 2022 report of the Lancet Countdown on health and climate change: health at the mercy of fossil fuels.Lancet. 2022; 400: 1619-1654Summary Full Text Full Text PDF PubMed Scopus (116) Google Scholar The sources of greenhouse gases—namely, the combustion of fossil fuels—are the main sources of harmful air pollution. The literature has extensively analysed the health co-benefits of lowered air pollution associated with alternative decarbonisation strategies.2Markandya A Sampedro J Smith SJ et al.Health co-benefits from air pollution and mitigation costs of the Paris Agreement: a modelling study.Lancet Planet Health. 2018; 2: e126-e133Summary Full Text Full Text PDF PubMed Scopus (327) Google Scholar, 3Reis LA Drouet L Tavoni M Internalising health-economic impacts of air pollution into climate policy: a global modelling study.Lancet Planet Health. 2022; 6: e40-e48Summary Full Text Full Text PDF PubMed Scopus (17) Google Scholar However, these studies have been focused on stylised or cost-optimal scenarios with long-term optimistic and uncertain assumptions about future mitigation efforts. The 2021 United Nations Climate Change Conference in Glasgow increased the ambition for the 2030 emission reduction targets compared with the 2015 pledges, and several countries presented their commitment to achieve net zero emissions by the second half of the century. Nevertheless, there are several alternative strategies to achieve net zero economies, which would result in very different emission pathways.4Iyer G Ou Y Edmonds J et al.Ratcheting of climate pledges needed to limit peak global warming.Nat Clim Change. 2022; 12: 1129-1135Crossref Scopus (5) Google Scholar Considering the uncertainty in the beyond 2030 decarbonisation plans and given that emission reduction policies are mainly defined up to 2030, we estimated the health co-benefits up to 2030 attributable to ambient air pollution reductions associated with existing climate policies and pledges (ie, nationally determined contributions) for the world at a regional level. We first calculated the health co-benefits of the implementation of the current portfolio of emission reduction policies, such as renewable energy shares, vehicle fuel standards, and energy efficiency targets, for all G20 countries. We then estimated the co-benefits for a second scenario, in which the post-Glasgow emission reduction targets are implemented on top of existing policies. The scenarios include all the climate policies and emissions targets submitted or announced by June, 2022. If, in any region, current policies already achieve the nationally determined contributions target, no additional emission constraint is applied. On the other hand, in regions where the existing climate policies are not sufficient to achieve the mitigation target in the nationally determined contributions, the model endogenously estimates a regional carbon tax to achieve the nationally determined contributions based on the least cost approach. Van de Ven and colleagues provide a full description of these scenarios, with a complete list of the implemented polices and emission targets.5van de Ven D-J Mittal S Gambhir A et al.A multi-model analysis of post-Glasgow climate action and feasibility gap.Nat Clim Change. 2023; 13: 570-578Crossref Scopus (1) Google Scholar For calculations of the health co-benefits, we combine the Global Change Analysis Model (GCAM)6Calvin K Patel P Clarke L et al.GCAM v5.1: representing the linkages between energy, water, land, climate, and economic systems.Geosci Model Dev. 2019; 12: 677-698Crossref Scopus (155) Google Scholar with rfasst,7Sampedro J Khan Z Vernon C Smith S Waldhoff S Van Dingenen R rfasst: an R tool to estimate air pollution impacts on health and agriculture.J Open Source Softw. 2022; 73820 Crossref Google Scholar a tool designed to calculate a range of adverse health and agricultural effects attributable to air pollution for alternative scenarios. Greenhouse gases and air pollutant emission pathways are projected by GCAM and fed into rfasst, which calculates a range of health impacts attributable to both fine particulate matter (ie, PM2·5) and ozone exposure. In contrast to other studies that use a single health impact function, we used a combination of existing risk functions, including integrated exposure–response functions from the Global Burden of Diseases, Injuries, and Risk Factors Study,8Forouzanfar MH Afshin A Alexander LT et al.Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015.Lancet. 2016; 388: 1659-1724Summary Full Text Full Text PDF PubMed Scopus (3046) Google Scholar Burnett and colleagues,9Burnett RT Pope 3rd, CA Ezzati M et al.An integrated risk function for estimating the global burden of disease attributable to ambient fine particulate matter exposure.Environ Health Perspect. 2014; 122: 397-403Crossref PubMed Scopus (1279) Google Scholar and Jerret and colleagues,10Jerrett M Burnett RT Pope 3rd, CA et al.Long-term ozone exposure and mortality.N Engl J Med. 2009; 360: 1085-1095Crossref PubMed Scopus (1050) Google Scholar and the Global Exposure Mortality Model11Burnett R Chen H Szyszkowicz M et al.Global estimates of mortality associated with long-term exposure to outdoor fine particulate matter.Proc Natl Acad Sci USA. 2018; 115: 9592-9597Crossref PubMed Scopus (1133) Google Scholar (including and excluding the Chinese cohort that covers much of the exposure distribution; appendix). We found that global premature mortality associated with ambient air pollution will reduce in the short term (up to 2030), accounting for 166 623 (lower and upper bounds obtained by combining lower and upper parameters within the health impact functions: 72 789–260 347) avoided deaths per year worldwide due to existing climate policies, and 361 744 (151 698–571 779) avoided deaths per year worldwide due to the implementation of updated nationally determined contributions on top of current policies. Thus, the additional contribution of the nationally determined contributions is of the order of 195 121 avoided deaths per year. Although the contribution of both the current policies and climate pledges is a positive co-benefit, we estimate that there will still be 5·5 million (2·77–8·23) premature mortalities attributable to exposure to both PM2·5 and ozone in 2030 globally. Hence, avoided premature mortalities associated with current policies and pledges are relatively small, representing around 2·6–3·2% for climate policies, and 5·2–6·5% with the addition of nationally determined contributions. Regionally, we found that the regions that benefit the most from the implementation of the existing climate policy portfolio are central Europe and China, which have 80 avoided premature deaths per million people and 69 avoided premature deaths per million people, respectively. Health co-benefits in other regions are substantially smaller, and in some regions (eg, South Korea) premature mortalities could even be increased compared with baseline, due to the increase in biomass for electricity generation and the subsequent increase in organic carbon emissions. In the climate policies and national determined contributions scenario, avoided premature mortalities per million people are larger in all regions, and heavily concentrated in Central Asia (148 avoided premature mortalities per million people), China (100 avoided premature mortalities per million people), Central Europe (98 avoided premature mortalities per million people), and India (77 avoided premature mortalities per million people). In summary, health co-benefits associated with current policies and nationally determined contributions are relatively small. The results show that to reduce health impacts attributable to ambient air pollution rapidly, additional policy action that is explicitly designed for tackling air pollutant emissions will be needed. First, emissions per unit of activity should be urgently reduced through technological progress (eg, flue-gas desulphurisation) and more stringent emission controls and regulation. In our projections, emission factors for the alternative pollutants moderately decrease over time in all the scenarios, following the central trends in existing literature. Having faster and more pronounced decreases, particularly in the most affected regions, will produce direct health co-benefits. In addition, disentangling climate action from air pollution can create additional hazards for human health. The large-scale deployment of low-carbon technologies, such as biomass or carbon capture and storage, although effectively reducing greenhouse gas emissions, will not decrease the emissions of harmful air pollutants (eg, nitrogen oxides and organic carbon), which highlights the need to integrate human health considerations into climate policy making.12Vandyck T Rauner S Sampedro J et al.Integrate health into decision-making to foster climate action.Environ Res Lett. 2021; 16041005 Crossref Scopus (4) Google Scholar We declare no competing interests. Editorial note: The Lancet Group takes a neutral position with respect to territorial claims in published text, maps, and institutional affiliations. Download .pdf (.39 MB) Help with pdf files Supplementary appendix

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