Climate Crisis: Half the Planet Experienced an Extra Month of Extreme Heat Last Year

New findings have sparked significant concern, revealing that half of the global population endured an additional month of extreme heat last year compared to the average from 1991-2020 due to human-induced global warming. The research, published on Friday (30.05.25), underscores the detrimental impact of continued fossil fuel use on health and prosperity worldwide, with developing countries facing particularly unknown consequences, according to scientists. “With every barrel of oil burned, every ton of carbon dioxide released, and every fraction of a degree temperature increase, heatwaves will affect more people,” noted Friederike Otto, a climatologist at Imperial College London and co-author of the report. Conducted by scientists from World Weather Attribution, Climate Central, and the Climate Centre of the Red Cross Red Crescent, the analysis was released ahead of World Heat Action Day on June 2, dedicated this year to the exhaustion risks caused by heatwaves. Researchers assessed the period from May 1, 2024, to May 1, 2025, defining ‘extreme heat days’ as those exceeding 90% of the average temperatures recorded in a specific location during 1991–2020. By comparing these figures to a hypothetical world without human-induced warming, results showed nearly four billion people—49% of the global population—experienced at least 30 extra days of extreme heat over the past year. The study documented 67 extreme heat episodes within the year, all bearing the fingerprint of climate change. Aruba in the Caribbean was most affected, experiencing 187 extreme heat days—45 more than expected in a world without climate change. The year 2024 marked the hottest year ever recorded, surpassing 2023, while January 2025 was the warmest on record. Globally, temperatures over the last five years have been 1.3°C higher than pre-industrial levels, with 2024 crossing the symbolic 1.5°C limit set by the Paris Climate Agreement. The report also highlights the alarming lack of data on heat’s health impacts in poorer regions. While Europe recorded over 61,000 heat-related deaths in the summer of 2022, minimal data exists for other areas, with many heat-related fatalities misattributed to heart or respiratory conditions.