People cool themselves under a water cooling station at the Smithsonian National Zoo in Washington, D.C., the United States, July 26, 2023. (Photo by Aaron Schwartz/Xinhua)

The dog days of summer are not just barking, they are biting. Our planet has just endured a season of simmering - the hottest summer on record. Climate breakdown has begun.

UNITED NATIONS, Sept. 6 (Xinhua) -- UN Secretary-General Antonio Guterres warned on Wednesday that "climate breakdown has begun."

The UN chief released a strongly worded statement on a record summer of global warming in the Northern Hemisphere, according to the European Union's climate service Copernicus and the World Meteorological Organization (WMO).

"The dog days of summer are not just barking, they are biting," the secretary-general said, adding that "our planet has just endured a season of simmering - the hottest summer on record. Climate breakdown has begun."

The top UN official said that "scientists have long warned what our fossil fuel addiction will unleash."

"Our climate is imploding faster than we can cope with extreme weather events hitting every corner of the planet."

A girl cools herself at a fountain of Three Graces on the Place de Comedie as the highest temperature reaches 38 degrees Celsius in Montpellier, southern France, July 19, 2023. (Xinhua/Gao Jing)

"Surging temperatures demand a surge in action," said the secretary-general.

Guterres called on leaders to "turn up the heat now for climate solutions."

"We can still avoid the worst of climate chaos - and we don't have a moment to lose," he said.

Earth has sweltered through its hottest Northern Hemisphere summer ever measured, with a record warm August capping a season of brutal and deadly temperatures, according to the WMO.

Last month was not only the hottest August scientists ever recorded by far with modern equipment, it was also the second-hottest month measured, behind only July 2023, WMO and Copernicus announced Wednesday.