PARIS: Extreme heat will reach dangerous levels — even for younger people — across an area equivalent to the size of the United States if Earth´s global warming hits two degrees Celsius, scientists warned on Tuesday.

Climate change is driving an increasing number of deadly heatwaves across the world, exposing a growing number of people to conditions that test the limits of human endurance.

Last year, more than 1,300 people died at the hajj pilgrimage in Saudi Arabia where temperatures hit 51.8C.For this study, published in the journal Nature Reviews Earth and Environment, researchers looked at global warming and the effects of searing heat on the human body.

They found a significant increase in the area of the world potentially exposed to unsafe temperatures, with people in North Africa and South Asia most at risk.

They considered both dangerous and unsurvivable heat levels — where the body´s core temperature increases to 42C within six hours.

The study concluded that between 1994 and 2023, heat and humidity reached unsafe levels for people aged under 60 in areas equivalent to about two percent of global land area.

For more vulnerable older people, that rose to about 20 percent of land area.

Lead author Tom Matthews said the research highlights the “potentially deadly consequences” of the Earth´s average temperature rising 2C above pre-industrial levels.

The Paris climate agreement, an internationally binding treaty, aims to limit warming to “well below” 2C and preferably to 1.5C. Last year was the first to exceed 1.5C on average.