Already, at roughly 1.1C (2F) of warming, people experienced about 86 days of health-threatening high temperatures on average in 2022, the report from the Lancet medical journal found.

People over 65 have been the most vulnerable to soaring temperatures, with deaths in this age group attributed to rising temperatures up 47% in the past decade compared with how many people died during the period from 1991 to 2000.

The findings, assembled by more than 100 experts from 52 different research institutions and United Nations agencies including the World Health Organization, deepen concerns over the health impacts posed by heat.

A study earlier this year indicated that some 61,000 people were likely to have died during European heatwaves in the summer of 2022.

“We are paying in lives,” report executive director Marina Romanello said of the world’s inaction on climate change.

The Lancet report, the eighth of its kind to assess how climate change is affecting health outcomes globally, also found that heat exposure may have led to 490 billion lost labour hours in 2022, up nearly 42% from the 1991 to 2000 period.

More frequent heatwaves could also cause food insecurity for an additional 525 million people by mid-century.

The United Nations’ annual climate change conference, COP28, in Dubai later this month will focus in part on health impacts for the first time.

Some 46 million health professionals have called on the COP28 presidency to push for a phaseout of fossil fuels.

(Reporting by Gloria Dickie in London; editing by Mark Heinrich)