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Heatwave days per person, observed and attributable to climate change, world

Heatwave days that people were exposed to on average each year, 2020–2024, as observed, as expected in a modelled climate without human-caused warming, and the difference attributable to climate change, from the Lancet Countdown (indicator 1.1.1).

Latest value

30.8days

World, 2024. Version 2025 report.

Heatwave days per person, observed and attributable to climate change, world (days per person)

15 values from 2020 to 2024. Lines: Observed, Expected without human-caused climate change, Attributable to climate change.
Show as a table
Heatwave days per person, observed and attributable to climate change, world, every value
PeriodScenarioValue (days)Status
2020Observed16.1final
2021Observed14.9final
2022Observed12.3final
2023Observed22.5final
2024Observed30.8final
2020Expected without human-caused climate change1.9final
2021Expected without human-caused climate change2.3final
2022Expected without human-caused climate change2.3final
2023Expected without human-caused climate change3.8final
2024Expected without human-caused climate change5.0final
2020Attributable to climate change14.2final
2021Attributable to climate change12.6final
2022Attributable to climate change10.0final
2023Attributable to climate change18.8final
2024Attributable to climate change25.8final
Lancet Countdown on Health and Climate Change, 2025 report data: indicator 1.1.1 by A. J. Pershing and J. Giguere (attributable heatwave days) and by F. Tartarini and O. Jay (vulnerable populations); indicator 1.1.3 by C. Freyberg, B. Lemke and M. Otto; indicator 1.1.5 by J. Ballester, X. Basagaña and J. Ruiz-Cabrejos. Romanello et al., The Lancet, 2025, doi:10.1016/S0140-6736(25)01919-1. CC BY-NC-SA 4.0. CC BY-NC-SA 4.0.

Where it comes from

Producer
Lancet Countdown on Health and Climate Change (led by University College London) · Lancet Countdown 2025: heat-related deaths, work hours lost to heat and heatwave exposure
Version
2025 report
File
https://lancetcountdown.org/wp-content/uploads/2025/10/Indicator-1.1.1_Attributable_Data-Download_2025-Lancet-Countdown-Report-1.xlsx
Fetched
2026-10-04 (automatically), 205,138 bytes
Fingerprint
sha256 53a22362f5b35c8cf91aa9d6c9f8ce0e7c97ce36f198f0b793ad70437989f632ETag "32152-6425ae06a502f" · Last-Modified Thu, 30 Oct 2025 07:05:39 GMT
Copies
No Wayback copy recorded yet.Our copy of the exact file
Cite the producer
Romanello M, Walawender M, Hsu S-C, et al. The 2025 report of the Lancet Countdown on health and climate change. Lancet 2025; published online Oct 29. https://doi.org/10.1016/S0140-6736(25)01919-1.

What was done to it

  1. Read the sheet '2025_Report _Data_Global' of the indicator 1.1.1 (attributable heatwave days) workbook of the Lancet Countdown 2025 report, 2020–2024: heatwave days observed, expected without climate change (Counterfactual) and attributable to climate change (Attributable_to_CC), published as in the workbook.

    Code: pipeline/src/envdash/transforms/impacts/lancet_countdown.py · code sha256 fd77ef680e809205… · inputs 53a22362f5b3…

  2. Checked that observed days equal expected days plus attributable days in every year.

    Code: pipeline/src/envdash/transforms/impacts/lancet_countdown.py · code sha256 fd77ef680e809205… · inputs 53a22362f5b3…

What it covers

Geography
World
Basis
A heatwave is at least two consecutive days when both minimum and maximum temperature exceed the local 1986–2005 95th percentile. Observed days from ERA5; days expected without human-caused warming from 24 paired CMIP6 climate model simulations.
Unit
days per person (days)