Global heating pushes tropical regions towards limits of human livability

(The Guardian, 8 Mar 2021) Rising heat and humidity threatening to plunge much of the world’s population into potentially lethal conditions, study finds.

The climate crisis is pushing the planet’s tropical regions towards the limits of human livability, with rising heat and humidity threatening to plunge much of the world’s population into potentially lethal conditions, new research has found.

Should governments fail to curb global heating to 1.5C above the pre-industrial era, areas in the tropical band that stretches either side of the equator risk changing into a new environment that will hit “the limit of human adaptation”, the study warns.

Humans’ ability to regulate their body heat is dependent upon the temperature and humidity of the surrounding air. We have a core body temperature that stays relatively stable at 37C (98.6F), while our skin is cooler to allow heat to flow away from the inner body. But should the wet-bulb temperature – a measure of air temperature and humidity – pass 35C, high skin temperature means the body is unable to cool itself, with potentially deadly consequences.

“If it is too humid our bodies can’t cool off by evaporating sweat – this is why humidity is important when we consider livability in a hot place,” said Yi Zhang, a Princeton University researcher who led the new study, published in Nature Geoscience. “High body core temperatures are dangerous or even lethal.”

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The Guardian, 8 Mar 2021: Global heating pushes tropical regions towards limits of human livability