The Lancet Planetary Health, March 2025

Are there more cold deaths than heat deaths?

Non-optimal temperatures are now considered among the leading risk factors of mortality worldwide. A global analysis showed that 9·4% of all deaths can be attributed to both cold and hot non-optimal temperatures, corresponding to about 5 million deaths.

In most epidemiological studies, excess cold deaths far outnumber heat deaths. In that same global analysis, of the 9·4% attributable temperature-related deaths, 8·5% (range 6·2–10·5%) were cold-related and only 0·9% (range 0·6–1·4%) were heat-related, which corresponds to approximately 4·6 million deaths from cold and about 489 000 from heat, a ratio of roughly 9:1 of cold versus heat. This pattern is also consistent in regional studies. In this Comment we summarise why this pattern emerges and address what this implies for future temperatures and related mortality under climate change.