The emerging syndemic of climate change and non-communicable diseases

Abstract

WHO has identified climate change as the greatest health threat of the 21st century.1WHOWHO calls for urgent action to protect health from climate change – Sign the call.https://www.who.int/news/item/06-10-2015-who-calls-for-urgent-action-to-protect-health-from-climate-change-sign-the-call#:~:text=WHO%20calls%20on%20the%20global,unacceptable%20risks%20to%20global%20healthDate: Oct 6, 2015Date accessed: June 10, 2024Google Scholar The 2015 Rockefeller Foundation–Lancet Commission found that six of nine planetary boundaries had been breached, including land system change, freshwater depletion, and biodiversity loss, with ocean acidification approaching the boundary. These planetary boundaries interact with climate change and will also pose considerable challenges to health.2Whitmee S Haines A Beyrer C et al.Safeguarding human health in the Anthropocene epoch: report of The Rockefeller Foundation–Lancet Commission on planetary health.Lancet. 2015; 386: 1973-2028Summary Full Text Full Text PDF PubMed Scopus (1602) Google Scholar, 3Richardson K Steffen W Lucht W et al.Earth beyond six of nine planetary boundaries.Sci Adv. 2023; 9eadh2458 Crossref Scopus (293) Google Scholar Also, non-communicable diseases (NCDs), are the leading cause of death globally, responsible for approximately 90% of deaths.1WHOWHO calls for urgent action to protect health from climate change – Sign the call.https://www.who.int/news/item/06-10-2015-who-calls-for-urgent-action-to-protect-health-from-climate-change-sign-the-call#:~:text=WHO%20calls%20on%20the%20global,unacceptable%20risks%20to%20global%20healthDate: Oct 6, 2015Date accessed: June 10, 2024Google Scholar Climate change has a range of effects on health, including through exposure to extreme heat, floods, and droughts; air pollution from wildfires; increased risks of a range of infectious diseases and vector-borne diseases; undernutrition; and population displacement. However, the complex relationships between climate change and NCDs are not widely understood. In this Comment, we explore the synergism between climate change and NCDs and also show how climate change mitigation and adaptation actions can also reduce NCD risks. The figure (appendix) shows some of the inter-relationships between climate change and NCDs. This inter-relationship can also be described as a syndemic due to the aggregation of two concurrent, synergistic threats (ie, climate change and NCDs) and the interaction between factors in the complex system that exacerbates both, as described by a 2019 Lancet Commission that pointed to links with both undernutrition and obesity.4Swinburn BA Kraak VI Allender S et al.The global syndemic of obesity, undernutrition, and climate change: the Lancet Commission report.Lancet. 2019; 393: 791-846Summary Full Text Full Text PDF PubMed Scopus (1543) Google Scholar The figure shows some of the many important pathways between greenhouse gas (GHG) emissions and NCDs, including through climatic changes (eg, altered rainfall patterns and changes in mean and extreme temperatures), climate-related disasters (eg, flooding, landslides, and droughts), and indirect factors (eg,migration). These changing conditions affect NCD outcomes (eg, cancer, diabetes, and mental health) and risk factors (eg, stress, air pollution, and physical activity). Fossil fuel combustion is the major driver of climate change, and the resulting ambient air pollution has been estimated to cause about 3·6 million premature deaths annually.5Lelieveld J Klingmüller K Pozzer A Burnett RT Haines A Ramanathan V Effects of fossil fuel and total anthropogenic emission removal on public health and climate.Proc Natl Acad Sci USA. 2019; 116: 7192-7197Crossref PubMed Scopus (487) Google Scholar The figure also shows that human activities that lead to NCDs (eg, tobacco and alcohol production) also produce substantial GHG emissions, thus exacerbating climate change. Policies to mitigate climate change can have major co-benefits for NCDs and vice versa. For example, policies to replace fossil fuel combustion with access to clean renewable energy can reduce NCD risks from ambient air pollution and cut GHG emissions.6Haines A McMichael AJ Smith KR et al.Public health benefits of strategies to reduce greenhouse-gas emissions: overview and implications for policy makers.Lancet. 2009; 374: 2104-2114Summary Full Text Full Text PDF PubMed Scopus (426) Google Scholar Supporting walking, cycling, and public transport can both improve health through increased physical activity and reduce air pollution and carbon emissions by decreasing dependence on travel in private motorised vehicles. Food systems were responsible for approximately 34% of annual GHG emissions in 2015.7Crippa M Solazzo E Guizzardi D Monforti-Ferrario F Tubiello FN Leip A Food systems are responsible for a third of global anthropogenic GHG emissions.Nat Food. 2021; 2: 198-209Crossref PubMed Scopus (1076) Google Scholar Promotion of sustainable, healthy food systems could improve the availability of and access to healthy diets while reducing the environmental impact of food production. Reducing production of alcohol and tobacco products can lower their detrimental impact on the environment and carbon emissions through transport, water use, and packaging. There is growing awareness of and evidence for the large societal benefits that can result from policies to ensure multiple health co-benefits while mitigating climate change. For example, the dietary patterns that contribute to the rising burden of diet-related NCDs are also responsible for a disproportionate share of the environmental impact of the food system. Dietary change can, therefore, reduce the food system's adverse environmental and health impacts.8Nelson ME Hamm MW Hu FB Abrams SA Griffin TS Alignment of healthy dietary patterns and environmental sustainability: a systematic review.Adv Nutr. 2016; 7: 1005-1025Summary Full Text Full Text PDF PubMed Scopus (257) Google Scholar Several international initiatives have defined dietary patterns that are both health-promoting and environmentally sustainable. These diets usually emphasise fresh or minimally processed foods that are predominantly plant-based, with only moderate amounts of animal-sourced and ultraprocessed foods.8Nelson ME Hamm MW Hu FB Abrams SA Griffin TS Alignment of healthy dietary patterns and environmental sustainability: a systematic review.Adv Nutr. 2016; 7: 1005-1025Summary Full Text Full Text PDF PubMed Scopus (257) Google Scholar It has been estimated that worldwide adherence to such a diet would reduce global GHG emissions from the food system by half, even without changes to agricultural production techniques and a reduction of food waste,9Willett W Rockström J Loken B et al.Food in the Anthropocene: the EAT–Lancet Commission on healthy diets from sustainable food systems.Lancet. 2019; 393: 447-492Summary Full Text Full Text PDF PubMed Scopus (5532) Google Scholar and would accrue substantial health benefits.8Nelson ME Hamm MW Hu FB Abrams SA Griffin TS Alignment of healthy dietary patterns and environmental sustainability: a systematic review.Adv Nutr. 2016; 7: 1005-1025Summary Full Text Full Text PDF PubMed Scopus (257) Google Scholar However, not all actions that promote environmental sustainability would also promote health (including a reduction in NCDs) and vice versa, and trade-offs should be considered. For example, fish and dairy products, which can contribute to healthy diets, have substantial environmental footprints.10Béné C Barange M Subasinghe R et al.Feeding 9 billion by 2050—putting fish back on the menu.Food Secur. 2015; 7: 261-274Crossref Scopus (0) Google Scholar Conversely, food processing (which is primarily focused on supporting commercial products rather than protecting the environment) can help to increase environmental sustainability (eg, by extending shelf life and reducing food waste) but does not reduce the prevalence of NCDs and ultraprocessed foods can confer health risks. Yet, fish is one of the most efficient converters of feed into high quality food and its carbon footprint is lower than other animal production systems.10Béné C Barange M Subasinghe R et al.Feeding 9 billion by 2050—putting fish back on the menu.Food Secur. 2015; 7: 261-274Crossref Scopus (0) Google Scholar NCDs are linked to natural resources and the environment. For example, pollutants that bioaccumulate in animals could contribute to the development of NCDs when those animals are consumed by humans.11Natterson-Horowitz B Desmarchelier M Winkler AS Carabin H Beyond zoonoses in One Health: non-communicable diseases across the animal kingdom.Front Public Health. 2022; 9807186 Crossref Scopus (5) Google Scholar Furthermore, climate change is increasing the risks of emergencies and disasters, such as extreme weather events. In summary, as climate change accelerates, NCDs will be exacerbated. Implementing holistic solutions to health and climate change will require multisectoral action. Working group 2 of the Sixth Assessment Report of the IPCC acknowledges the need to care for ecosystems, biodiversity, and human communities in tandem, both globally and regionally. Holistic solutions are required that bring NCD and climate change stakeholders closer together, such as integrating NCDs into Nationally Determined Contributions. The inclusion of NCDs in Nationally Determined Contributions provide an opportunity for all countries to realise their commitment to the Paris Agreement through holistic health-promoting policies and multisectoral actions. The recent adoption of the World Health Assembly 77 Resolution on Climate Change and Health provides a timely and relevant policy tool for countries to integrate climate change in all policies, including NCD prevention, and advocate for mitigation measures that would deliver health co-benefits. SW, KW, FR, GG, and HK are staff members of WHO. The authors alone are responsible for the views expressed in this publication, and they do not necessarily represent the views, decisions, or policies of the institutions with which they are affiliated. All other authors declare no competing interests. Download .pdf (.22 MB) Help with pdf files Supplementary appendix

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