New report: Climate change added average of 26 days of extreme heat over last year

These two children, walking beneath a sun umbrella in a drought-affected part of Mozambique, offer an example of the solutions people often resort to protect themselves during extreme heat.  With heatwaves getting more frequent and intense, the IFRC says more must be done to help people adapt.

These two children, walking beneath a sun umbrella in a drought-affected part of Mozambique, offer an example of the solutions people often resort to in order protect themselves during extreme heat. With heatwaves getting more frequent and intense, IFRC says more must be done to help people adapt.

Photo: Aurélie Marrier d’Unienville/IFRC

Heat Action Day (2 June) to focus attention on an unprecedented twelve months

On Tuesday (28 May), Red Cross Red Crescent Climate Centre, World Weather Attribution and Climate Central released a report looking at the role climate change played in increasing the number of extreme heat days around the world over the last twelve months. It was already known that 2023 was the hottest on record. The report confirmed that almost all the world’s population was affected by extreme heat days caused by human-induced climate change. Across all places in the world, an average of 26 days were ‘excess’ extreme heat days which would probably not have occurred without climate change. (Methodology below) 
Heat Action Day – organised by the Red Cross Red Crescent Climate Centre – draws attention to the threat of extreme heat and what can be done to mitigate it. National Red Cross and Red Crescent Societies around the world are sharing ideas via a dedicated website. As part of a ‘Heat Action Sprint’ - organised alongside USAID and launched at a Heat Summit in late March – people are being urged to hold events and share artwork to highlight the danger of extreme heat to lives and livelihoods. Attention is needed this year more than any other. 
  • There is an ongoing extreme heatwave in Asia – across Bangladesh, Myanmar, Nepal, Malaysia and The Philippines. 
  • Across Bangladesh alone, the extreme heat has hit 57 of 64 districts, well over 120 million people. In Myanmar an extreme temperature of 48.2°C was recorded on 28 April – the highest ever in the country. In Nepal, the city of Nepalgunj is in the grip of weeks of temperatures of more than 40°C. 
  • There have been long-lasting recent heatwaves this year across swathes of Africa too.  
  • Extreme heat is known to have killed tens of thousands of people over the last 12 months, but the real number is likely in the hundreds of thousands or even millions. Unlike sudden ‘event’ weather disasters, heatwaves kill more slowly and less obviously; they are often exacerbators of pre-existing medical conditions. 
  • Heatwaves hit the vulnerable the hardest – the young, the old, the poor and those obliged to work outdoors.
National Red Cross and Red Crescent Societies are at the forefront of actions to mitigate extreme heat. In Bangladesh, for example, a first-ever ‘Early Action Protocol’ was launched last month, targeting 123,700 people with early warning messages, safe drinking water and oral saline solution, and cooling stations.  In Nepal, a three-year collaboration (between the IFRC, the Nepal Red Cross Society, city authorities and others) in the city of Nepalgunj has culminated in a detailed Heat Action Plan which is serving as a best-in-class example for cities around the world. Cities are where extreme heat is most dangerous so that’s where efforts are focused. Locally-led plans and adaptation, early warning systems, information campaigns and efforts focused on the most vulnerable are what saves lives.        
Jagan Chapagain, IFRC Secretary-General, said: 
“Flooding and hurricanes may capture the headlines, but the impacts of extreme heat are equally deadly. That’s why Heat Action Day matters so much. We need to focus attention on climate change’s silent killer. The IFRC is making heat - and urban action to reduce its impacts - a priority and remains committed to working with communities that are at risk of extreme heat through our global network of National Societies.” 
Aditya V. Bahadur, Director of the Red Cross Red Crescent Climate Centre said:   
“This report provides overwhelming scientific evidence that extreme heat is a deadly manifestation of the climate crisis.  This wreaks havoc on human health, critical infrastructure, the economy, agriculture and the environment, thereby eroding gains in human development and decreasing wellbeing- especially for poor and marginalized communities in the global South.”   
At 4pm on Tuesday 28 May, authors will hold a webinar briefing on the details of the report.  
For further details or requests for interviews: [email protected] 
Andrew Thomas +41 76 367 6587 
Tommaso Della Longa +41 797 084367 
Please use contacts above for the full report. 
Climate Central looked at the years 1991 to 2020 and worked out what temperatures counted as within the top 10% for each country over that period. 
Then Climate Central looked at the number of days between May 15 2023 and May 15 2024 (‘the recent year’) when peak temperatures were within, or beyond, the previous top 10% range.   
As a next step, they applied their Climate Shift Index (CSI), which uses peer-reviewed methodology to quantify the influence of climate change on daily temperatures. Where the CSI level was 2 or above (meaning climate change made the heat at least twice as likely), they counted the day in question as an excess heat day due to climate change.   
They compared the recent year's temperatures with counterfactual temperatures - the temperatures that would have occurred in a world without human-caused climate change. They counted the number of days with temperatures within or beyond the 'top 10%' band, and where the CSI said climate change made the temperatures at least twice as likely, and subtracted the number of times the counterfactual temperatures reached or exceeded this level.  
The conclusion? Over the last 12 months, human-caused climate change added — on average, across all places in the world — 26 more days of extreme heat than there would have been without it. 
6.8 billion people – 78% of world’s population – experienced at least 31 days (about one month) of extreme heat.   

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