Macroeconomics

Climatology

Ecology

Biology

Materials science

Range (aeronautics)

Economics

Humidity

Heat stress

Environmental health

Geology

Climate change

Geography

Productivity

Environmental science

Composite material

Extreme weather

Medicine

Meteorology

Atmospheric sciences

Extreme heat

Subtropics

Human health

Science Advances

Humans' ability to efficiently shed heat has enabled us to range over every continent, but a wet-bulb temperature (TW) of 35°C marks our upper physiological limit, and much lower values have serious health and productivity impacts. Climate models project the first 35°C TW occurrences by the mid-21st century. However, a comprehensive evaluation of weather station data shows that some coastal subtropical locations have already reported a TW of 35°C and that extreme humid heat overall has more than doubled in frequency since 1979. Recent exceedances of 35°C in global maximum sea surface temperature provide further support for the validity of these dangerously high TW values. We find the most extreme humid heat is highly localized in both space and time and is correspondingly substantially underestimated in reanalysis products. Our findings thus underscore the serious challenge posed by humid heat that is more intense than previously reported and increasingly severe.

The emergence of heat and humidity too severe for human tolerance