Researchers warn that more than a fifth of the human population will face extreme heat by 2100

A warning issued by researchers on Monday states that if current global warming policies continue, more than 20% of the global population will face extreme and potentially life-threatening heat by 2100. The report, published in the journal Nature Sustainability and reported by AFP, highlights the countries with the highest population at risk, including India, Nigeria, Indonesia, the Philippines, and Pakistan.

Lead author Tim Lenton, director of the Global Systems Institute at the University of Exeter, describes this potential scenario as a significant transformation in the habitability of the planet’s surface and suggests it could lead to large-scale relocations of populations.

The report emphasizes the urgent need to take action to limit global warming to 1.5 degrees Celsius. By doing so, the number of people at risk would be reduced to around half a billion, which is approximately 5% of the projected global population of 9.5 billion.

The study highlights the human cost of failing to address the climate emergency, noting that for every 0.1-degree Celsius of warming above present levels, approximately 140 million more people will be exposed to dangerous levels of heat.

The report identifies a threshold for “dangerous heat” at a mean annual temperature of 29 degrees Celsius (MAT). Human settlements historically have been concentrated around two MATs, 13 degrees Celsius in temperate zones and 27 degrees Celsius in tropical regions. However, global warming is pushing temperatures higher, increasing the risk of surpassing the 29 degrees Celsius threshold in regions already close to it.

Research has shown that sustained high temperatures beyond this threshold are strongly linked to higher mortality rates, reduced productivity, and crop yields, as well as increased likelihoods of conflict and infectious diseases.

The study reveals that the number of people exposed to such extreme heat has significantly increased over the past 40 years, from 12 million to five times that number, and this trend is expected to continue steeply in the coming decades.