July is set to become the world’s hottest month on record, as fossil fuel emissions drive climate change and the increasing intensity of heat waves across the Northern Hemisphere.

The first 21 days of the month were the hottest three-week period on record, with July 6 seeing the highest ever global average temperature, according to the European Union’s Earth observation agency Copernicus.

Following the hottest ever June, that puts 2023 on course to be the warmest year. Heat waves have baked North America, Asia and Europe this summer, with a record temperature for China recorded last week and California’s Death Valley approaching the global high of 56.7C set 110 years ago. That’s threatening the health of millions, while triggering thousands of wildfires from Greece to Canada.

“Climate-wise, the last few weeks have been rather remarkable,” Carlo Buontempo, director of the Copernicus Climate Change, Service told reporters on Thursday. “If we look at the top 21 hottest days, in terms of the global mean temperature, they have all occurred this month.”

Copernicus, which tracks data going back to 1940, said Thursday that average global sea temperatures well above normal have contributed to rising heat since May. The average global mean surface air temperature went above 17C for the first time this month.

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“The extreme weather which has affected many millions of people in July is unfortunately the harsh reality of climate change and a foretaste of the future,” said Petteri Taalas, the World Meteorological Organization’s secretary general. “The need to reduce greenhouse gas emissions is more urgent than ever before. Climate action is not a luxury but a must.”

The extreme weather has also included flooding from Delhi to New York and violent storms with hailstones larger than tennis balls in northern Italy. It’s also contributing to turmoil in global food markets after India banned key rice exports amid drought fears.

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The development of the first El Niño weather pattern in almost four years is expected to intensify the climate crisis into 2024. The warmest year on record is 2016, when there was a strong El Niño event.

“Typically we see increases in global temperatures which peak in the year following the El Niño event,” said Christopher Hewitt, director of WMO climate services. “So in this case we would expect to see a peak in temperatures in 2024.”