More than 2,700 people died from heat-related causes during the record-breaking heatwaves in May and June, according to a rapid analysis by researchers from Imperial College London, the Met Office, and the London School of Hygiene and Tropical Medicine (LSHTM). The study estimated 2,700 excess deaths in England and Wales over the two heatwave periods, with 42% of those deaths attributed to the extra heat caused by human activity, primarily burning fossil fuels.
May and June Heatwave Death Toll
The analysis examined the periods around the extreme heat events: May, when temperatures peaked at 35.1°C, and June, which set new monthly highs above 37°C with high humidity. Using weather data, climate models, and heat-related mortality research, the team estimated about 550 deaths occurred during the nine-day May heatwave, and approximately 2,200 deaths during the 11-day June heatwave in England and Wales. Of these, around 59% (327 people) in May and 38% (825 people) in June were attributable to climate change.
Climate Change Amplifies Heat Risk
The researchers warn that maximum daytime temperatures are now 3°C to 4°C hotter than they would be without climate change, significantly increasing health risks. High temperatures are linked to heat exhaustion, heat stroke, cardiovascular and kidney stress, and exacerbation of chronic conditions such as heart disease, lung disease, and diabetes. Heat also worsens mental health, increases violence, and raises drowning risk. Dr. Mark McCarthy of the Met Office described the heatwaves as “exceptional,” noting that May daytime temperatures were widely 15°C above average, and the June heatwave featured consecutive red warnings for extreme heat with notable humidity. “This combination of extreme daytime heat, high humidity, and hot nights all act to really contribute and increase the impact these heatwaves have on our infrastructure, transport, agriculture, and particularly on our health and wellbeing,” he said.
Urgent Adaptation Needed
Dr. Clair Barnes from Imperial College London stressed that heatwaves are the “most dangerous kind of extreme weather,” urging authorities to treat extreme heat with the same seriousness as winter flu. “People need to be aware that we are now seeing dangerous climate-change fuelled heat that is claiming lives, disrupting schools and hospitals, and shutting down transport and infrastructure. It’s time we woke up to the fact that we now live in a country with dangerously hot summers,” she said, calling for urgent adaptation and net-zero emissions efforts. The independent Climate Change Committee has warned that the UK is unprepared, with 92% of homes at risk of overheating by mid-century, and has recommended maximum temperature rules in workplaces and air conditioning in hospitals, care homes, and schools.
Official Responses and Next Steps
Professor Lea Berrang Ford of the UK Health Security Agency (UKHSA) said the modelled estimates “provide an important indication of the potential health impacts of sustained hot weather” and help illustrate the scale of risk and the growing threat of climate change. The UKHSA is due to publish its official interim analysis of heat-death impacts based on mortality data in the coming weeks. Secretary of State for Energy Security and Net Zero, Ed Miliband, stated: “The Government will not leave our children and grandchildren to face the costs of climate breakdown and nature loss… we are working with others to drive action bringing energy security and lower bills, backing British businesses and creating good jobs, and protecting our home and countryside for future generations.” Zack Polanski, leader of the Green Party of England and Wales, said: “These deaths are on the hands of politicians who have failed to act over the years… without action to protect people from extreme heat, we will see thousands more deaths in the years to come.” The London Ambulance Service reported its busiest week ever during the June heatwave, with a record number of life-threatening emergencies. Deputy Chief Paramedic Alison Blakely urged Londoners to “take the heat seriously, stay hydrated, and avoid strenuous activity during the hottest parts of the day.”
