The Science of Survival

Research indicates that even complete cessation of greenhouse gas emissions would not prevent centuries of continued warming as Earth’s systems adjust to find a new equilibrium. This “committed warming” means communities must prepare for unprecedented conditions that will persist for generations (King et al. 2024).

Understanding Wet-Bulb Temperature

The combination of heat and humidity, measured as wet-bulb temperature, determines human survivability outdoors. When wet-bulb temperatures exceed 35°C (95°F), sweating can no longer cool the human body effectively, leading to potentially fatal heat stress within hours. Studies have documented wet-bulb temperatures approaching this threshold in South Asia, the Persian Gulf, and other regions (Raymond et al. 2022).

Climate projections show that by 2040, many populated regions will regularly experience dangerous wet-bulb temperatures. These conditions will occur most frequently in coastal areas where high humidity combines with extreme heat. Urban areas face particular risks due to the heat island effect, which can add 3-5°C to local temperatures (Iles et al. 2024).

Current Impacts and Trends

Recent data shows:

• Maximum wet-bulb temperatures increasing 1.5 times faster than average temperatures
• More regions experiencing previously rare extreme heat events
• Urban areas reaching dangerous heat-humidity combinations more frequently
• Heat-related mortality rising globally, particularly in vulnerable populations

These trends indicate that heat adaptation must become a primary focus of climate resilience planning.

References:

Iles CE, et al. 2024. Strong regional trends in extreme weather over the next two decades under high- and low-emissions pathways. Nature Geoscience 17: 845-850.

King AD, et al. 2024. Exploring climate stabilisation at different global warming levels in ACCESS-ESM-1.5. Earth System Dynamics 15: 1353-1383.

Raymond C, et al. 2022. The emergence of heat and humidity too severe for human tolerance. Science Advances 6(19): eaaw1838.