Overview

• Researchers attribute at least 30 additional extreme heat days between May 2024 and May 2025 to human-caused warming, affecting roughly half the global population.
• The World Meteorological Organization and Met Office predict an 86 percent likelihood of one year exceeding 1.5°C above pre-industrial levels and an 80 percent chance of surpassing 2024’s temperature record before 2030.
• Tropical and small island regions saw the sharpest rises in heat, with Caribbean territories logging up to 187 extra hot days and Southeast Asian cities recording nearly 100 additional extreme heat days.
• Extended heatwaves have driven increases in heat-related illnesses and deaths, strained energy and healthcare systems, disrupted agriculture and amplified economic costs.
• Experts warn that only rapid fossil fuel phase-out paired with expanded early warning systems, urban heat action plans and long-term planning can curb escalating heat risks.