Lancet: Record 710,000 Heat Deaths in 2023, Calls for Global Health Emergency

The 2026 Lancet Countdown reports a record 710,000 heat-related deaths in 2023, with average annual heat mortality in the post-Paris decade nearly 36% higher than in the previous one. Over 70% of those deaths are attributed to human-caused climate change, and researchers urge formal recognition of climate change as a global health emergency ahead of COP31.

• 710,000 heat deaths in 2023 is the highest single-year figure in the Lancet Countdown series
• Average annual heat deaths post-Paris are nearly 36% higher than the prior decade
• More than 70% of 2023 heat deaths are attributed to human-caused climate change
• The report involved 146 researchers from 71 institutions across over 30 countries