WASHINGTON, May 30 (Alliance News): Nearly half the world’s population experienced an additional month of extreme heat over the past year due to manmade climate change, according to a new global study released ahead of Heat Action Day.
The research, conducted by World Weather Attribution, Climate Central, and the Red Cross Red Crescent Climate Centre, found that around four billion people — or 49% of the global population — endured at least 30 extra days of extreme heat between May 1, 2024, and May 1, 2025.
The scientists defined “extreme heat days” as those hotter than 90% of temperatures recorded at each location between 1991 and 2020. Using peer-reviewed modelling, they compared this data to a world without human-induced climate change — and the contrast was stark.
The Caribbean island of Aruba was the worst affected, with 187 extreme heat days — 45 more than expected in a climate not impacted by human activity. Overall, 67 extreme heat events were recorded, all linked to global warming.
“This study clearly shows that with every tonne of carbon released, more people are exposed to dangerous heat,” said Friederike Otto, climate scientist at Imperial College London and co-author of the report.
The findings follow record-breaking temperatures, with 2024 confirmed as the hottest year on record, surpassing 2023. January 2025 also marked the warmest January ever recorded. On a five-year average, global temperatures now stand at 1.3°C above pre-industrial levels — with 2024 alone exceeding the 1.5°C threshold set by the Paris Agreement.
Researchers also raised alarms about the lack of health data from low-income countries, where many heat-related deaths go unrecorded or are misattributed to other causes.
The report urges urgent action through early warning systems, public awareness campaigns, improved building designs, and behavioural adaptations.
However, the authors stress that only a rapid global phase-out of fossil fuels can halt the intensifying heat crisis.
