Human-Caused Climate Change Amplifies UK Heatwaves, Study Finds

A recent study revealed that human-induced climate change will accelerate the occurrence and intensity of heatwaves in the UK beyond previous predictions. The heatwave that took place on July 18 and 19, 2022, shattered temperature records as it surpassed 40°C. With limited experience in dealing with extreme heat, the UK faced widespread suffering. The strain on care services supporting the elderly and vulnerable was immense—emergency calls surged, hospitalisations increased, and early estimates indicate that nearly 1,000 heat-related deaths sadly occurred.

Conducted by a global team of renowned climate scientists from the World Weather Attribution group, the study determined that the heatwave was at least ten times more likely due to human influence on climate change. Despite this finding, such an intense heatwave remains rare in today's climate.

Dr. Mariam Zachariah, Research Associate at the Grantham Institute - Climate Change and Environment at Imperial College London, who led the study, stated, ‘The maximum day-time temperature on July 19 was so extreme that it was a rare 1-in-1,000-year event, even in the current climate. The likelihood of the average temperature over the two days was also rare, with a 1 in 100 chance. However, these temperatures would have been statistically impossible in a world before the Industrial Revolution.’

To quantify the impact of climate change on that heatwave, researchers employed observed data from weather stations across the UK and computer-based climate simulations. By comparing today's climate—warmed by 1.2ºC, due to human influence—with a natural climate, they found that greenhouse gas emissions caused the recent heatwave to increase by 2ºC. However, historical weather records suggest that, without human-caused climate change, the heatwave would have been 4ºC cooler.

This disparity suggests that current climate models underestimate the true impact of human-induced climate change on high temperatures in the UK and Western Europe. Moreover, the study's findings are likely conservative, indicating that climate change may have increased the event's frequency by more than the estimated factor of ten.

Dr. Friederike (Fredi) Otto, co-author and Senior Lecturer at the Grantham Institute and lead of the World Weather Attribution project, highlighted the concerning trend: ‘In Europe and other parts of the world, we are seeing more and more record-breaking heatwaves causing extreme temperatures that have become hotter faster than in most climate models. It's a worrying finding that suggests that, if carbon emissions are not rapidly reduced, the consequences of climate change on extreme heat in Europe could be even worse than we previously thought.’

Heatwaves pose a significant risk to the UK, a nation unaccustomed to very high temperatures. Dr. Zachariah explained that ‘our lifestyle and infrastructure are not designed for prolonged exposure to such temperatures’. For instance, extreme heat causes railway tracks to buckle. The impact of heatwaves becomes increasingly profound even with seemingly small increases in temperature.

The UK's infrastructure is ill-equipped to handle heatwaves, with over 570,000 homes unsuitable for high temperatures, rendering them uninhabitable during extreme heat events. Larger structures, such as prisons and hospitals, also struggle to cope. During heatwaves, green spaces, shade, and water are lifelines.

Certain demographics in the UK experienced more severe impacts from the heatwave. Urban infrastructure contributed to higher temperatures in London compared to surrounding areas, affecting poorer communities with limited access to water and fewer available green spaces, making it difficult to escape the intense heat.

Additionally, the following groups are particularly vulnerable during heatwaves:

• Homeless individuals, who face heightened exposure to extreme heat

• Elderly individuals or those with chronic health conditions like diabetes, who have a higher likelihood of succumbing to heat-related complications

• Ethnically diverse communities, who already face health inequalities exacerbated during the Covid-19 pandemic, will continue to be affected by extreme temperatures

As heatwaves become more frequent, researchers emphasise the need for the government to consider the diverse impacts on different groups when devising strategies to mitigate the effects. Roop Singh, co-author and Climate Risk Adviser at the Red Cross Red Crescent Climate Centre, remarked, ‘Heatwaves are the deadliest type of extreme weather event in Europe, killing thousands each year. But they don't have to be. Many of these deaths are preventable if adequate adaptation plans are in place. Without rapid and comprehensive adaptation and emissions cuts, the situation will only get worse.’