Over the past few years, the lethal humidity crisis has become real. Gone from hypothetical to reality with deaths across the middle East, India and South East Asia. Lethal humidity is not the spoken face of climate crisis. In 2023, the IPCC stated that one of the greatest hazards posed by near-term 1.5°C warming was the impact of “dangerous” humid heatwaves on human mortality. At temperatures as low as 30°C (86°F), under conditions of high humidity, the human body struggles to cool down by sweating.
Death will result.
Scientists are increasingly worried about the death toll caused by humid heatwaves, and how it will escalate in the near-term. This year is now the hottest year on record, overtaking the previous hottest year of 2023, and 2024.
Research and Climate Action
As Dr Andrew Forrest, who is funding research [2] points out
- “Wet-bulb temperatures” (the combination of temperature and humidity) must not rise over 30°C
- Older people are more susceptible than younger people.
- In 2010, scientists said a webbulb temperature of 35°C was survivable. We now know that is more like 30°C
- If you cannot get to air conditioning you will die.
- Humidity switches off your thermoregulation.
- You die in six hours, painful death.
- Death is binary.
- Lethal humidity is binary.
- Lethal humidity happens inside election terms. It’s not 2050 or even 2030.
- Lethal humidity events are happening all over the world right now because of escalating humidity.
- Since 1979, periods of extreme humid heat have more than doubled in frequency globally,
- Humidity rises seven to 10 times quicker than heat.
Lethal Humidity and Temperature
The relationship between humidity and temperature is shown below
1300 Pilgrims Dead
The Conversation reported in 2024 [1] that over 1300 pilgrims died due to lethal humidity in just one incident. Not everyone on the pilgrimage had access to air conditioning. Temperatures will get worse in 25 years time as the timing of Hajj will cycle back to peak summer in August and September. At 2°C of warming, the risk of heatstroke during Hajj would be ten times higher.
References
- More than 1,300 Hajj pilgrims died this year when humidity and heat pushed past survivable limits. It’s just the start 2024 https://theconversation.com/more-than-1-300-hajj-pilgrims-died-this-year-when-humidity-and-heat-pushed-past-survivable-limits-its-just-the-start-245271
- Minderoo Foundation to fund A$6 million worth of new research combatting lethal humidity 2023 https://www.minderoo.org/media/minderoo-foundation-to-fund-au6-million-worth-of-new-reseach-combatting-lethal-humidity/
