Editing IPCC:AR6/WGIII/Chapter-3 (section)

=== 3.7.5 Health ===

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SDG 3 (good health and well-being) aims to ensure healthy lives and promote well-being for all at all ages. Climate change is increasingly causing injuries, illnesses, malnutrition, threats to mental health and well-being, and deaths (AR6 WGII Chapter 7). Mitigation policies and technologies to reduce GHG emissions are often beneficial for human health on a shorter time scale than benefits in terms of slowing climate change ( [[#Limaye--2020|Limaye et al. 2020]] ). The financial value of health benefits from improved air quality alone is projected to exceed the costs of meeting the goals of the Paris Agreement ( [[#Markandya--2018|Markandya et al. 2018]] ).

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==== 3.7.5.1 Benefits of Avoided Climate Impacts Along Mitigation Pathways ====

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The human health chapter of the WGII contribution to the AR6 concluded that climate change is increasingly affecting a growing number of health outcomes, with negative net impacts at the global scale and positive impacts only in a few limited situations. There are few estimates of economic costs of increases in climate-sensitive health outcomes. In the USA in 2012, the financial burden in terms of deaths, hospitalisations, and emergency department visits for ten climate-sensitive events across 11 states were estimated to be 10 (2.7–24.6) billion USD2018 ( [[#Limaye--2019|Limaye et al. 2019]] ).

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==== 3.7.5.2 Implications of Mitigation Efforts Along Pathways ====

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Transitioning toward equitable, low-carbon societies has multiple co-benefits for health and well-being (AR6 WGII Chapter 7). Health benefits can be gained from improvements in air quality through transitioning to renewable energy and active transport (e.g., walking and cycling); shifting to affordable low-meat, plant-rich diets; and green buildings and nature-based solutions, such as green-and-blue urban infrastructure, as shown in Figure 3.40 ( [[#Iacobucci--2016|Iacobucci 2016]] ).

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[[File:c13ea31566f7d629d55da1c5b788aa24 IPCC_AR6_WGIII_Figure_3_40.png]]

'''Figure 3.40 | Diagram showing the co-benefits between health and mitigation.''' Source: with permission from [[#Iacobucci--2016|Iacobucci 2016]] .

The avoided health impacts associated with climate change mitigation can substantially offset mitigation costs at the societal level ( [[#Ščasný--2015|Ščasný et al. 2015]] ; [[#Schucht--2015|Schucht et al. 2015]] ; [[#Chang--2017|Chang et al. 2017]] ; [[#Markandya--2018|Markandya et al. 2018]] ). Models of health co-benefits show that a 1.5°C pathway could result in 152 million ± 43 million fewer premature deaths worldwide between 2020 and 2100 in comparison to a business-as-usual scenario, particularly due to reductions in exposure to PM2.5 ( [[#Shindell--2018|Shindell et al. 2018]] ; [[#Rauner--2020a|Rauner et al. 2020a]] ; [[#Rafaj--2021|Rafaj et al. 2021]] ). Some of the most substantial health, well-being, and equity benefits associated with climate action derive from investing in basic infrastructure: sanitation, clean drinking water, clean energy, affordable healthy diets, clean public transport, and improved air quality from transformative solutions across economic sectors including agriculture, energy, transport and buildings ( [[#Chang--2017|Chang et al. 2017]] ).

The health co-benefits of the NDCs for 2040 were compared for two scenarios, one consistent with the goal of the Paris Agreement and the SDGs and the other also placing health as a central focus of the policies (i.e., health in all climate policies scenario) ( [[#Hamilton--2021|Hamilton et al. 2021]] ), for Brazil, China, Germany, India, Indonesia, Nigeria, South Africa, the UK, and the USA. Modelling of the energy, food and agriculture, and transport sectors, and associated risk factors related to mortality, suggested the sustainable pathways scenario could result in annual reductions of 1.18 million air pollution-related deaths, 5.86 million diet-related deaths, and 1.15 million deaths due to physical inactivity. Adopting the more ambitious health in all climate policies scenario could result in further reductions of 462,000 annual deaths attributable to air pollution, 572,000 annual deaths attributable to diet, and 943,000 annual deaths attributable to physical inactivity. These benefits were attributable to the mitigation of direct GHG emissions and the commensurate actions that reduce exposure to harmful pollutants, as well as improved diets and safe physical activity.

Cost-benefit analyses for climate mitigation in urban settings that do not account for health may underestimate the potential cost savings and benefits ( [[#Hess--2020|Hess et al. 2020]] ). The net health benefits of controlling air pollution as part of climate mitigation efforts could reach trillions of dollars annually, depending on the air quality policies adopted globally ( [[#Markandya--2018|Markandya et al. 2018]] ; [[#Scovronick--2019b|Scovronick et al. 2019b]] ). Air pollution reductions resulting from meeting the Paris Agreement targets were estimated to provide health co-benefits-to-mitigation ratios of between 1.4 and 2.5 ( [[#Markandya--2018|Markandya et al. 2018]] ). In Asia, the benefit of air pollution reduction through mitigation measures was estimated to reduce premature mortality by 0.79 million, with an associated health benefit of USD2.8 trillion versus mitigation costs of USD840 billion, equating to 6% and 2% of GDP, respectively ( [[#Xie--2018|Xie et al. 2018]] ). Similarly, stabilising radiative forcing to 3.4 W m –2 in South Korea could cost USD1.3–8.5 billion in 2050 and could lead to a USD23.5 billion cost reduction from the combined benefits of avoided premature mortality, health expenditures, and lost work hours ( [[#Kim--2020|Kim et al. 2020]] ). The health co-benefits related to physical exercise and reduced air pollution largely offset the costs of implementing low-CO 2 -emitting urban mobility strategies in three Austrian cities ( [[#Wolkinger--2018|Wolkinger et al. 2018]] ).

Just inthe USA, over the next 50 years, a 2°C pathway could prevent roughly 4.5 million premature deaths, about 3.5 million hospitalisations and emergency room visits, and approximately 300 million lost workdays ( [[#Shindell--2020|Shindell 2020]] ). The estimated yearly benefits of USD700 billion were more than the estimated cost of the energy transition.

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