‘Dangerous’ heatwaves expected to sweep the tropics daily through 2100: study

Many millions of people in the tropics could be exposed to dangerous heat for half a year by 2100, even if humanity manages to meet climate targets, researchers warned on Thursday.

In the most likely scenario, the world would miss those targets — leaving people in the tropics exposed to harmful temperatures on most days of a typical year by the end of the century, the study found.

If emissions are not controlled, many people in these regions could potentially experience “nightmare” periods of extreme heat.

“Unless we pull ourselves together, there is a possibility that billions of people could be really, really overexposed to these extremely dangerous temperatures in ways that we haven’t really seen before,” said lead author Lucas Vargas Zeppetello of the Harvard University University.

Severe heat waves – made even hotter and more frequent by climate change – are already being felt around the world, threatening human health, wildlife and crop yields.

Most climate projections predict temperature increases under different policy scenarios, but do not say which of these paths is more likely.

In this study, published in the journal Communications Earth and Environment, researchers estimated potential exposure to dangerous heat and humidity.

They used statistical projections to predict the level of carbon emissions from human activity and the resulting global warming.

They found that many people in tropical regions could be exposed to dangerous heat levels for half a year by the end of the century, even if the global temperature limit falls to the Paris Climate Agreement target of less than two degrees Celsius (35.6 degrees Fahrenheit) above pre-industrial levels increases levels.

Outside the tropics, they said deadly heat waves are likely to occur annually.

The researchers used a heat index that puts “dangerous” levels at 39.4C, while temperatures above 51C are considered “extremely dangerous” and completely unsafe for humans.

The extreme measure was originally developed for people working in scorching indoor environments like a ship’s boiler room and has rarely been observed outdoors, Zeppetello said.

But by the end of the century, the researcher said it was “virtually guaranteed” that people in some parts of the tropics would experience this level of heat every year unless emissions were severely curtailed, particularly in parts of sub-Saharan Africa and India at risk .

“It’s pretty scary,” he told AFP, adding that even walking outdoors in these conditions would be dangerous.

The earth has warmed by nearly 1.2°C so far, and current projections, based on countries’ pledges to reduce carbon emissions, would see the world meet the Paris Agreement’s 2°C target for 2100 far exceeds, let alone the more ambitious target of 1.5°C.

In their research, Zeppetello and colleagues analyzed predictions from global climate models, population projections, and examined the relationship between economic growth and carbon emissions.

They estimated that there is only a 0.1 percent chance of limiting global average warming to 1.5°C by 2100 and project that the world will likely reach 1.8°C by 2050.

The researchers found that in 2100 the most likely global average temperature increase would be 3°C, which Zeppetello said would mean “nightmarish” conditions for many people.

In a worst-case scenario, where emissions continue unabated, extreme temperatures in parts of the tropics could last for up to two months each year.

But he said it depends on how quickly humanity can reduce emissions.

“We don’t have to go into this world. At the moment there’s nothing to say it’s a certainty, but people need to be aware of how dangerous that would be if it happened,” he said.

The researchers said that under all scenarios, there could be a sharp rise in heat-related illnesses, particularly among the elderly, vulnerable and those who work outdoors.

“I think that’s a very important point that gets way too little attention,” said Kristin Aunan, a research professor at the Center for International Climate Research specializing in emissions and human health, who was not involved in the study.

“Limited outdoor workability could have major economic implications in addition to the human suffering caused by working in extreme temperatures,” she told AFP, adding that crop production and livestock farming can also be affected by extreme temperatures.