Why Climate Change is a Public Health Crisis

Across the UK and Europe, climate change is increasingly reflected in headlines and daily life. Reports of record temperatures, winter flooding and prolonged dry spells have become more familiar, alongside coverage of severe floods in Spain and Germany and sustained heatwaves in France and Italy. These events are often discussed in terms of infrastructure damage, economic cost and environmental impact.

While the health implications are increasingly recognised, they are often less visible in public debate. The same conditions driving floods and heatwaves are also shaping patterns of illness and mortality. In the UK, higher temperatures, air pollution and the consequences of flooding are contributing to increased hospital admissions, worsening long-term conditions and placing additional pressure on health services.

Climate change is not only an environmental or economic issue. It is also a public health issue, and one that is already unfolding.

Climate Change as a Public Health Threat

Public health experts increasingly describe climate change as one of the greatest threats to human health in the twenty-first century. The World Health Organization estimates that between 2030 and 2050, climate change will result in approximately 250,000 additional deaths each year globally from heat exposure, malnutrition, malaria, and diarrhoeal disease alone. This figure does not include wider impacts on cardiovascular disease, respiratory illness, mental health, or health system disruption.

In the UK, rising temperatures, shifting rainfall patterns and more frequent extreme weather events are already influencing health outcomes. Analysis from the UK Health Security Agency and national climate risk assessments indicates that, without adaptation, heat-related mortality, flood-associated illness, respiratory disease linked to air pollution and pressure on health services are all expected to increase.

How Climate Risks Translate into Health Impacts

Climate change affects health through several interconnected pathways. Some are direct, such as heat stress. Others operate through the environments and systems that shape everyday health.

In the UK, the most significant impacts include:

• Extreme heat, driving excess deaths and emergency admissions during increasingly frequent heatwaves, including more than 3,000 excess deaths recorded in England and Wales during the summer of 2022
• Flooding and severe weather, damaging homes and disrupting services, with around 6.1 million people in the UK currently living in flood-prone areas
• Worsening air quality, exacerbating respiratory and cardiovascular disease in major urban centres, with air pollution estimated to cost the NHS and social care £1.6 billion (2017–2025)
• Changing infectious disease risks, as warmer conditions shift food-borne illness patterns and expand suitability for vectors such as ticks
• Impacts on food security, water quality and wider wellbeing, particularly for vulnerable communities facing climate-related disruption

Among these pathways, heat provides one of the most immediate and measurable examples of climate-related risk.

How Rising Temperatures are Reshaping UK Summers

Climate change in the UK is visible in long-term temperature records. Recent decades show a clear shift away from the historical averages that shaped how our homes, infrastructure and health services were designed.

The graph above compares average summer temperatures over the past century against a baseline from 1884 to 1920. This baseline reflects the climate conditions that informed much of the UK’s built environment and public health planning. Comparing temperatures across this period shows when the UK began consistently exceeding its historical summer averages.

What was once considered an exceptionally hot summer is increasingly becoming typical. Rising averages are altering the baseline conditions in which people live and work, increasing the scale and frequency of heat-related health risks.

When Heat Becomes a Health Risk

When temperatures exceed typical seasonal levels, the body can struggle to regulate heat. This increases the risk of dehydration, heat exhaustion, cardiovascular strain and worsening respiratory conditions, particularly among older adults and people living with chronic illness.

Extreme heat also affects the health system directly. During major heat events, the NHS records measurable increases in:

• Emergency department attendances
• Hospital admissions for cardiovascular and respiratory conditions
• Excess mortality, particularly among vulnerable groups

Analysis from the Office for National Statistics shows that mortality risk rises once temperatures exceed expected norms. This pattern is commonly measured using Relative Risk, which compares mortality at higher temperatures to the rate observed at the most favourable temperature.

Why This Matters for the Future of Health Services

The interaction between climate trends and healthcare demand is becoming increasingly clear. Changes in temperature, flooding patterns and air quality are already influencing illness patterns, seasonal pressures and long-term service planning across the UK.

Adaptation measures, including heat-health alert systems, climate-resilient buildings and targeted support for vulnerable communities, can reduce the impact of extreme weather on health. Strengthening data and analytics will also be essential to identify emerging risks, allocate resources effectively and plan services for a changing climate.

References

1. World Health Organization. Climate change and health. WHO; 2023.
   https://www.who.int/health-topics/climate-change
2. UK Health Security Agency. Health Effects of Climate Change (HECC) in the UK: State of the evidence 2023. UKHSA; 2023.
   https://www.gov.uk/government/publications/health-effects-of-climate-change-hecc-report
3. Office for National Statistics. Excess mortality during heat-periods: England and Wales, 1 June to 31 August 2022. ONS; 2022.
   https://www.ons.gov.uk/peoplepopulationandcommunity/birthsdeathsandmarriages/deaths/articles/excessmortalityduringheatperiods/englandandwales1juneto31august2022
4. Met Office. UK Climate Projections (UKCP18). Met Office; 2018.
   https://www.metoffice.gov.uk/research/approach/collaboration/ukcp
5. UK Health Security Agency. Heat mortality monitoring report: 2023. UKHSA; 2023.
   https://www.gov.uk/government/publications/heat-mortality-monitoring-reports/heat-mortality-monitoring-report-2023
6. Department for Environment, Food and Rural Affairs. Air quality and emissions statistics. DEFRA; 2023.
   https://www.gov.uk/government/collections/air-quality-and-emissions-statistics
7. Office for Health Improvement and Disparities. Air pollution: Applying All Our Health. UK Government; 2022.
   https://www.gov.uk/government/publications/air-pollution-applying-all-our-health/air-pollution-applying-all-our-health
8. Royal College of Physicians. Every breath we take: The lifelong impact of air pollution. RCP; 2016.
   https://www.rcp.ac.uk/improving-care/resources/every-breath-we-take-the-lifelong-impact-of-air-pollution/
9. UK Health Security Agency. Climate change and infectious diseases in the UK (HECC Chapter 7). UKHSA; 2023.
   https://www.gov.uk/government/publications/health-effects-of-climate-change-hecc-report/chapter-7-infectious-diseases
10. Committee on Climate Change. Independent assessment of UK climate risk (CCRA3). CCC; 2021.
    https://www.theccc.org.uk/publication/independent-assessment-of-uk-climate-risk/
11. NHS England. Fourth Health and Climate Adaptation Report. NHS England; 2024.
    https://www.england.nhs.uk/long-read/4th-health-and-climate-adaptation-report/
12. The Health Foundation. Health and climate change: Complex problems with co-benefits. Health Foundation; 2022.
    https://www.health.org.uk/publications/long-reads/health-and-climate-change-complex-problems-with-co-benefits