Major Cities Experience 25% Surge in Extreme Heat Days Since 1990s

Major global cities are experiencing a 25-26% increase in extremely hot days annually compared to the 1990s, with the International Institute for Environment and Development (IIED) reporting a rise from an average of 1,062 days above 35°C between 1994-2003 to 1,335 days between 2015-2024 across 43 populous capitals. This surge is driven by global heating from fossil fuel use, intensifying heatwaves and disproportionately affecting vulnerable populations, especially the elderly and those living in low-income or informal settlements. Cities like Rome, Beijing, Manila, Madrid, London, and many in Africa, Asia, and Latin America have seen significant increases in hot days, with 2024 marking the hottest year on record in the study period. Experts warn that inadequate urban infrastructure and poor housing quality exacerbate risks, underscoring the urgent need for governments to adapt city environments and reduce greenhouse gas emissions to protect residents from escalating heat stress. Anna Walnycki of IIED emphasized that global temperatures are rising faster than anticipated and that failure to act will leave millions exposed to dangerous urban heat island effects. The findings highlight the critical challenge of climate adaptation in the face of accelerating warming and population growth in major cities worldwide.