Climate Change, Heatwaves, and the Menace of Wet-Bulb Temperatures

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Climate adaptation Too hot and humid to live, know the dangers of Wet bulb temperatures

Increasing temperatures due to climate change are bringing more heatwaves that are already stretching our body’s limit to cope.

Previous heatwaves have shown that these events can cause fatalities or severe medical conditions like heatstroke. Prolonged and intense heat also severely impacts the economy – through reduced human productivity, while heat and drought pose a significant threat to food security and agricultural production.

Another threat lurking from the combined high heat and humidity could be potentially fatal due to rising temperatures. Researchers termed this condition a wet-bulb temperature (TW), a temperature threshold that limits our body’s ability to cool itself through sweating.

See our blog posts Climate change and Heatwaves are increasing Incidents of Wet-bulb Temperatures

The study, “The emergence of heat and humidity too severe for human tolerance”, says that we have a sophisticated cooling system consisting of our locomotion, naked skin, and sweat glands. This allows us to thermoregulate, which is our body’s ability to dissipate heat or gain and reduce heat loss.

But when temperatures reach a wet-bulb temperature because of high heat and humidity, our body loses the ability to thermoregulate through sweating, which gradually increases our core body, and things could turn bad quickly, resulting in heat stroke, organ failure or even death in just a matter of hours.

As temperatures rise due to climate change, combining heat, humidity, geography, and meteorology can make wet-bulb incidents more common.

A paper in 2010 theorized that a 35°C wet bulb was the upper limit where humans could survive heat stress, and only after six hours our body’s temperature could reach 40°C before things become lethal.

However, experiments and studies have shown that the body’s upper limit is lower than 35°C for things to get deadly. What is this new wet-bulb temperature threshold?

The video below explains what the wet-bulb temperature is, what regions in the world are more prone to wet bulb temperature, the conditions that it will take to create wet-bulb temperature, what is the highest wet-bulb temperature recorded and in what location, and how we can be safe from wet-bulb temperatures.


Raymond, C., Matthews, T., & Horton, R. (2020, May 8). The emergence of heat and humidity too severe for human tolerance. Science Advances. Retrieved from

Too HOT and HUMID to Live: Extreme Wet Bulb Events Are on the Rise. (10 May 2023). PBS Terra [Video]. Retrieved from

Sherwood, S. C., & Huber, M. (2010). An adaptability limit to climate change due to heat stress. Proceedings of the National Academy of Sciences107(21), 9552-9555.

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