Climate crisis, cities, and health

More than ever, the climate crisis is becoming a health crisis. An estimated 5 million people globally die each year because of suboptimal temperatures, with a large proportion of heat-related mortality (37%) attributable to human-induced climate change. The last few years have been the hottest on record and high temperatures claimed over 60 000 lives in Europe alone in 2022, with cities the most affected and temperatures in cities projected to increase. Urban heat islands that result from excessive asphalt and concrete in cities contribute to an increase in temperature and premature mortality. Just over half of the world’s population (56%) now lives in cities and that percentage is expected to reach nearly 70% by 2050.

The Conference of the Parties (COP) had its first health day at COP28 and over 120 countries have endorsed the COP28 UAE Declaration on Climate and Health. This historic and important event recognises and provides evidence that the climate crisis is also a health crisis and that people’s health can benefit from climate action. The Declaration promotes the health arguments for climate action and health co-benefits of mitigation and discusses the strengthening climate resilience of health systems. Currently, the impacts of the climate crisis already lead to large health burdens and health-care costs. Therefore, climate action is also about preventing premature deaths and disease and reducing health-care costs.

Seven of eight globally quantified safe and just Earth system boundaries have already been exceeded. Cities, and particularly a high-income urban lifestyle, have a large impact on the planet, but are probably also the most sustainable way to house large populations. The ecological footprints of cities far exceed the surface area that they occupy, and urban areas cannot be decoupled from the peri-urban and rural areas on which they depend for resources. Urban areas cover only 3% of the Earth’s land surface, but accounted for 67–72% of combined global CO2 and CH4 emissions in 2020, and are a major contributor to biodiversity loss. However, cities can also provide key solutions to the climate crisis because of their proximity to everyday destinations and greater access to financial and human resources, knowledge, and innovation. In Europe, initiatives that aim to reduce greenhouse gas emissions and achieve carbon neutrality include the EU’s Green Deal, which is a response to the Paris Climate Agreement and provides a roadmap for cities.

A recent review of large-scale multiple city studies showed a clear relationship between urban and transport planning and environmental quality, greenhouse gas emissions, and health. Therefore, better urban planning could be a solution to reduce climate change impacts and improve health. The health co-benefits of climate action are well recognised and documented, but the urgency to implement them is still missing. Climate mitigation strategies targeting land use, transport, buildings, and waste management have shown multiple quantified health co-benefits, such as reduced premature mortality and rates of disease.

In this Lecture, I provide an overview of potential climate action measures at the nexus of urban planning, environment, climate, and health to achieve climate neutral, liveable, and healthy cities. This Lecture is not a comprehensive or systematic review, but provides a brief overview of possible climate actions that cities can implement and that can improve the health of citizens.

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IUMS Congress 2026


International Union of Microbiological Societies