UK Heat Extremes and Public Health: Risks, Futures, and Responses

Climate change is intensifying the frequency and severity of heat extremes worldwide, and the UK is no exception. Traditionally considered temperate, the UK has experienced record-breaking heat events in 2019, 2020, and 2022, with the summer of 2022 alone linked to nearly 3,000 excess deaths. The Met Office has warned that “extreme weather is the UK’s new normal.” and these events highlight a growing public health challenge that will intensify under future climate change.

The health impacts of heat extremes are not determined by temperature alone. Instead, they are shaped by compounding characteristics such as multi-day persistence, day-night extremes, interactions with humidity, and differences between indoor and outdoor exposures. These factors influence how heat translates into physiological stress and health risks. For example, hot nights reduce the body’s ability to recover from daytime heat, while high humidity limits evaporative cooling and exacerbates cardiovascular strain. Understanding these compounding features is critical for anticipating future risks and designing effective responses.

This PhD project aims to advance knowledge of how heat extremes impact health in the UK, what measures might mitigate these risks, and how they may evolve under climate change. It will make use of UK Biobank, a world-leading health cohort of 500,000 participants, linked with historical weather observations to generate individual-level evidence on heat-health relationships. By moving beyond population-level studies, the project will provide new insights by capture acute impacts (e.g., mortality, heat-related hospitalisations) chronic physical conditions (e.g., cardiovascular disease, respiratory illness, diabetes, kidney disease) and mental health outcomes (e.g., sleep disruption, stress, psychiatric admissions), capturing a fuller picture of disease burden and quality of life.

The project will combine these relationships with UK Climate Projections (UKCP18) and demographic scenarios to explore future risks. Scenario-based modelling will be used to assess a range of plausible futures, explicitly incorporating uncertainties in climate, demographics, and intervention uptake. This approach will also evaluate how mitigation measures, such as improved housing design, behavioural adaptation, or early warning systems, could reduce risks, while recognising the uncertainties linked to their adoption and effectiveness.

The project’s contributions include:
• Developing approaches to capture the compounding characteristics of heat extremes with direct relevance to health outcomes.
• Conducting individual-level analyses of mortality and morbidity under different types of heat extremes.
• Comparing risks of compounding extremes with isolated heat events.
• Investigating how impacts are distributed across population subgroups (e.g., by age, socioeconomic status, lifestyle, or residential environment) to reveal inequalities.
• Producing national, regional, and local projections of health risks and potential reductions under mitigation scenarios.

This work sits at the interface of climate science, data science, and public health, offering training in large-scale data handling, advanced statistical methods, and scenario-based modelling. It offers the opportunity to apply technical skills to a critical societal issue and to generate evidence that can directly inform public health policy, climate adaptation, and urban planning in the UK.

Extreme heat is one of the most certain and pressing consequences of climate change. By providing robust evidence on its health impacts and exploring possible solutions, this project offers a chance to make a meaningful contribution to protecting public health in a warming world.

This project is suited to students with a background in climate science, statistics, geography, epidemiology, maths, physics, or engineering who are keen to apply quantitative methods to pressing climate – health questions. Experience in statistical modelling, machine learning, or spatial analysis would be valuable, though training will be provided. An interest in working across disciplines – linking climate projections, health data, and policy applications – will be essential.

Supervisor profile:
https://environment.leeds.ac.uk/staff/12888/dr-yuchen-li
https://environment.leeds.ac.uk/see/staff/1162/dr-cathryn-birch
https://environment.leeds.ac.uk/transport/staff/10106/dr-zihao-an

Key readings:
Wu, X., Wang, J., Ge, Y., Lai, S., Zhang, D., Ren, Z., & Wang, J. (2025). Future heat-related mortality in Europe driven by compound day-night heatwaves and demographic shifts. Nature Communications, 16(1), 7420.

Cole, R., Wan, K., Murage, P., Macintyre, H. L., Hajat, S., & Heaviside, C. (2025). Projections of heat related mortality under combined climate and socioeconomic adaptation scenarios for England and Wales. PLoS Climate, 4(7), e0000553.

Jackson, L. S., Birch, C. E., Chagnaud, G., Marsham, J. H., & Taylor, C. M. (2025). Daily rainfall variability controls humid heatwaves in the global tropics and subtropics. Nature Communications, 16(1), 3461.