Climate Thoughts with Brian

Public protecting themselves against the direct sun

A new combined report from Imperial College London, the Met Office and the London School of Hygiene & Tropical Medicine estimated that more than 2,700 people died from heat-related causes in the recent May and June heatwaves. The report states that almost half of these (42%) died as ‘a result of the extra heat caused by human-induced warming.’

Researchers estimated that an excess of about 550 people died in the May heatwave, (21-29 May) and about 2,2000 in the June heatwave (18-28 June). The main findings of the report highlight that daytime maximum temperatures are now 3-4°C  hotter than they would have been without human-induced climate change, increasing the health risks associated with heatwaves.

These figures come only a few short years after the plus 40°C heat in England in 2022, where approximately 4,507 deaths were estimated to be linked to the heat. Within five years then, an estimated more than 7,000 people in England and Wales have died from heatwave-related deaths, highlighting the magnitude of this ‘silent killer.’ 

Dr. Clair Barnes, Research Associate in Extreme Weather and Climate Change, Imperial College London, and one of the study authors, said, ‘Every time we have a heatwave, our news is filled with reporters at swimming pools, images of people eating ice cream and sunbathers on beaches. We all love the sun, but 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.’

She continued, ‘It’s time we woke up to the fact that we now live in a country with dangerously hot summers. To protect people during future extremes, we must urgently adapt to the reality of the climate we now have, and double down on global efforts to reach net zero emissions to stop this from getting worse.’

The health-related dangers of heatwaves have not just impacted the UK in recent months.

In France, there has been an estimated 2,700 deaths in the June heatwave, while Germany has recorded an estimated 5,120 heat-related deaths this year, most of them in late June.

How the figures were reached

The authors of the study were at pains to point out that these estimated heatwave deaths were gathered using peer-reviewed methods, using high resolution data on a fine, granular level and would only be confirmed by Government figures in due course. In order to estimate them, they used two scenarios- a factual one of observed records and a ‘counterfactual’ scenario of a 1.4°C cooler world without human-induced climate change. A comparison between these two figures would then give the number of how many more people would have been expected to died in each small area of 1,000 to 3,000 residents.

For the May heatwave, London, the North East, and the East of England had the highest proportion of expected heat-related deaths of 64%, 87% and 70% respectively, while Wales recorded 47% of expected excess heat-related deaths owing to human caused climate change.

For the June heatwave, Wales dropped to 27% of excess heat-related deaths, while London and the North East had 42% and 46% respectively. That is, that almost half of the estimated excess heat-related deaths were owed to human caused climate change.

‘The temperature is the problem’

Recent advice from the World Health Organisation warned that ‘The number of people exposed to extreme heat is growing exponentially due to climate change in all world regions.’ They highlighted the underlying illnesses that can be exacerbated by high temperatures and heat stress, including diabetes, cardiovascular disease and asthma. They stated, ‘Heatstroke is a medical emergency with a high-case fatality rate.’ In recent days, other vulnerable groups have been discussed, as the BBC reported a 2025 study which suggested that women in general are more prone to be adversely impacted by heatwaves, owing to hormones and how women’s bodies respond to heat. Pregnant women are also an at risk group owing to difficulties in regulating their temperature. Other vulnerable groups were also highlighted in today’s report, highlighting the national scale of the pressing issue.. ‘In the UK, women, ethnic minorities, people in older age groups and those living in the most deprived areas have an increased risk of deaths during periods of heat.’

The WHO, however, wanted to focus on solutions, as well as identify at-risk groups, and stated, ‘Mitigating climate change by reducing greenhouse gas emissions is imperative and urgent to limit the magnitude of human costs from extreme heat.’ 

These calls for mitigation and adaption to reduce the number of people at risk, were echoed by the report published today, as Dr. Malcolm Mistry, Assistant Professor in Climate and Geo-spatial Modelling, London School of Hygiene & Tropical Medicine (LSHTM) said, ‘It is vital that action on adapting Britain’s homes, workplaces, and critical infrastructure to extreme heat outpaces these health risks, especially if we are to protect those most vulnerable to its impacts, such as older people, babies, and children.’

 He added ominously that, ‘We are still in the first half of summer in the UK and large parts of England and Wales have already experienced two record-breaking heatwaves, in May and June, triggering extreme heat-health alerts across England. With climate change driven by human activity making summer heatwaves more frequent and more intense, these spikes of extreme hot weather are rapidly evolving into a major health risk for people in the UK.’

Is the UK prepared for extreme temperatures?

In the released statement,  Dr. Mark McCarthy, Manager of Climate Attribution at the Met Office noted that, ‘2026 has been exceptional for the two early season heatwaves in May and June. These have smashed records that had stood from May 1944 and June 1976 respectively. For the time of year these events were extreme, even in our warmer climate.’ 

He highlighted that these exceptional tempeatures are not going away anytime soon and will leading to more frequent and more intense summer heatwaves. ‘However, it is clear that human-caused climate change is leading to more frequent and more intense summer heatwaves. This intensification is driving many impacts, including those affecting human health and mortality and other issues, such as agriculture, effects on transport infrastructure and biodiversity.’

‘Extreme heat is here’

The Mayor of London Sadiq Khan, drew attention to these intense temperatures when he posted on social media to launch a city heat plan, saying, ‘Extreme heat is here – and it’s a fixture of London’s future. That’s why we’ve launched Heat Ready London. It’s London’s first-ever city heat plan to help stop homes overheating, keep communities cool and save lives as we adapt to our new reality.’ 

Professor Lea Berrang Ford, Head of the UK Health Security Agency (UKHSA) Centre for Climate and Health Security (CCHS), warned about future heatwaves in the UK and the risks that would be increased without adaption and preparedness.

‘These modelled estimates are based on past trends in temperature effects on mortality and provide an important indication of the potential health impacts of sustained hot weather, particularly for the most vulnerable among us. While they are not a measure of observed mortality, they help illustrate the scale of risk associated with extreme heat and the growing threat climate change poses to our wellbeing. As set out in our most recent Health Effects of Climate Change report, periods of heat in the UK are likely to become more intense, longer and more frequent as the world continues to warm.’