Heat Action Day Report: Climate change and the escalation of global extreme heat

Researchers from World Weather Attribution assessed the influence of human-caused climate change on dangerous heat waves over the past 12 months, in collaboration with Climate Central and the Red Cross Red Crescent Climate Centre.

Published ahead of Heat Action Day on June 2, using World Weather Attribution criteria, the study identified 76 extreme heat waves that span 90 different countries. These events put billions of people at risk, including in densely populated areas of South and East Asia, the Sahel, and South America.

Over the 12-month period, 6.3 billion people (about 78% of the global population) experienced at least 31 days of extreme heat (hotter than 90% of temperatures observed in their local area over the 1991-2020 period) that was made at least two times more likely due to human-caused climate change.

Over the last 12 months, human-caused climate change added an average of 26 days of extreme heat (on average, across all places in the world) than there would have been without a warmed planet.