Lancet Countdown puts heat-related deaths at a record 710,000 for 2023

28 October 2026

The Lancet Countdown report, produced with the World Health Organization and led by University College London, estimates a record 710,000 heat-related deaths worldwide in 2023, and for the first time attributes more than 70 per cent of them to human-caused climate change. Heat exposure cost about 573 billion potential work hours in 2025, valued at 1.07 trillion dollars. Extreme drought has widened sharply: 51.8 per cent of land had at least one month of drought in 2025. Conditions suitable for dengue transmission rose 24 per cent for Aedes albopictus and 7 per cent for Aedes aegypti between the early 1980s and the decade to 2025. On the other side, clean energy jobs grew 2.3 per cent in 2024, clean energy investment reached a record 2.1 trillion dollars, and about one in four countries now has a plan to adapt health services to climate change, against 14 WHO member states in 2015. National climate-health laws have risen roughly fiftyfold since 2000, but wealthy nations hold 55 per cent of them.