U.N. Secretary-General Antonio Guterres is calling on countries to address the urgency of the extreme heat epidemic, fueled by climate change — days after the world registered its hottest day on record.

"Extreme heat is the new abnormal," Guterres said on Thursday. "The world must rise to the challenge of rising temperatures," he said.

Climate change is making heat waves more frequent, more intense and longer lasting across the world.

Already this year, scorching conditions have killed 1,300 Hajj pilgrims, closed schools for some 80 million children in Africa and Asia, and led to a spike in hospitalizations and deaths in the Sahel.

Every month since June 2023 has now ranked as the planet's warmest since records began in 1940, compared with the corresponding month in previous years, according the European Union's Copernicus Climate Change Service.

The U.N. called on governments to not only tamp down fossil fuel emissions — the driver of climate change — but to bolster protections for the most vulnerable, including the elderly, pregnant women and children, and step up safeguards for workers.

Over 70% of the global workforce — 2.4 billion people — are now at high risk of extreme heat, according to a report from the International Labour Organization (ILO) published Thursday.

In Africa, nearly 93% of the workforce is exposed to excessive heat, and 84% of the Arab States' workforce, the ILO report found.

Excessive heat has been blamed for causing almost 23 million workplace injuries worldwide, and some 19,000 deaths annually.

"We need measures to protect workers, grounded in human rights," Guterres said.

He also called for governments to "heatproof" their economies, critical sectors such as health care, and the built environment.

Cities are warming at twice the worldwide average rate due to rapid urbanization and the urban heat island effect.

By 2050, some researchers estimate a 700% global increase in the number of urban poor living in extreme heat conditions.

This is the first time the U.N. has put out a global call for action on extreme heat.

"We need a policy signal and this is it," said Kathy Baughman Mcleod, CEO of Climate Resilience for All, a nonprofit focused on extreme heat.

"It's recognition of how big it is and how urgent it is. It's also recognition that everybody doesn't feel in the same way and pay the same price for it."