Extreme heat days surge as temperature records tumble

A report published by Climate Central, World Weather Attribution, and the Red Cross Red Crescent Climate Centre has found a dramatic increase in extreme heat days around the world over the past year (from May 15, 2023 to May 15, 2024). This comes on the back of May 2024 being the 12th consecutive month of record high global temperatures.

More extreme, more often

The report defined a day of extreme heat as one in which temperatures met or exceeded the 90th percentile for average maximums between 1991 and 2020. That means that, for each location and time of year, a day of extreme heat would have been in the top 10 hottest days during the previous three decades.

The study found climate change has added an average of 26 more extreme heat days across all locations around the world. This hasn’t affected all countries equally: Suriname leads the way, with almost exactly half of its days (182) meeting the threshold for extreme heat, while Australia emerged relatively unscathed, with “only” 35 days of extreme heat on average across all parts of the country during 2023.

The human effects

According to the report, about 6.3 billion people globally – around 78 per cent of the population – have experienced 31 days or more of extreme heat over the past year. The researchers say these days have become at least twice as common due to human-driven climate change.

The study also identified 76 heatwaves across 90 countries during the one-year period. These events put billions of people at risk, including those in densely populated areas of South and East Asia and South America.

To meet the World Weather Attribution’s criteria, a heatwave must consist of three or more consecutive days of extreme heat or cause 10 or more people to die from heat-related illnesses in a certain location.

You can read the full report here.