News World Tropics face ‘deadly’ rise in heat, humidity: study
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Tropics face ‘deadly’ rise in heat, humidity: study

Tropics temperatures
People in the tropics could face 350 days of "deadly conditions" if emissions are not reduced. Photo: Getty
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Popular tropical holiday destinations are facing a rise in deadly temperatures and humidity if greenhouse gas emissions are not aggressively mitigated, an international study has found.

The Nature Climate Change Journal research has concluded the world’s tropics – including Indonesia, South America and the north of Australia – will become increasingly unliveable, with a possible 350 days of “deadly conditions” by 2100.

The research stated that about 30 per cent of the world’s population lives in conditions currently exceeding “deadly threshold levels” for up to 20 days a year.

If greenhouse gas emissions continue at their current rate, the tropics will be exposed to temperature and humidity conditions “near the deadly threshold year-round”, the report found.

The grim assessment would also expose 73.9 per cent of the world’s population to climates beyond what the human body can withstand by the end of the century.

Tropics temperatures
By 2100, the tropics could see 350 days a year of life-threatening temperatures. Photo: NCCJ

“By 2100, mid-latitudes will be exposed to 60 days per year compared to almost the entire year in humid tropical areas,” lead author and University of Hawaii department of geography professor Camilo Mora wrote.

“While it is understood that higher latitudes will undergo more warming than tropic regions, our results suggest that tropical humid areas will be disproportionately exposed to more days with deadly climatic conditions.”

Tropics temperatures
As of 2000, 30.6 per cent of the world’s population are exposed to severe conditions. Photo: NCCJ

Even under the most aggressive mitigation of climate change, the study found that 48 per cent of the planet would rise beyond acceptable limits.

It states high temperatures and humidity become life-threatening to humans as a result of the body’s inability to acclimatise to such extreme heat.

“The combination of an optimum body core temperature (that is, 37 degrees Celsius) and that an object cannot dissipate heat to an environment with equal or higher temperature,” Professor Mora said.

“[This] dictates that any ambient temperature above 37C (degrees Celsius) should result in body heat accumulation and a dangerous exceedance of the optimum body core temperature.”

He wrote that sweating, the main process by which the body dissipates heat, becomes ineffective in high humidity, with air saturated with water vapour prevents evaporation of sweat.

The study also states the consequences of exposure to dangerous conditions could be further aggravated by an ageing population – who are highly vulnerable to heat – and increasing urbanisation to accelerate its effects.

Professor Mora wrote immediate action on greenhouse emissions must be taken to prevent the earth’s killer heat becoming a reality.

“Our paper emphasises the importance of aggressive mitigation to minimise exposure to deadly climates and highlights areas of the planet where adaptation will be most needed,” he said.