The remarks by the secretary-general came after a virtual summit of over a dozen world leaders to discuss planning ahead of the major COP30 climate meeting later this year in Brazil.

In the meeting, major-emitter China vowed to not let up in combating climate change.

"Renewables are the economic opportunity of the century. Dissenters and fossil fuel interests may try to stand in the way. But as we heard today, the world is moving forward. Full-speed ahead," said Guterres after the meeting, co-organized with Brazilian President Luiz Inacio Lula da Silva.

Among the participants were Chinese President Xi Jinping, French President Emmanuel Macron, Turkey's Recep Tayyip Erdogan, Kenya's William Ruto and Chile's Gabriel Boric, as well as European Commission President Ursula von der Leyen and European Council President Antonio Costa.

"It was among the most diverse meetings of heads of state focused exclusively on climate in some time. Yet I heard a unifying message" toward action, Guterres said.

Xi told the meeting that "no matter how the international situation changes, China's efforts to combat climate change will not slow down," according to state broadcaster CCTV.

Xi also said China would announce its 2035 greenhouse gas reduction commitments, known as Nationally Determined Contributions (NDCs), before COP30 in November, and that it would cover all greenhouse gases, not just carbon dioxide.

At a separate Greenpeace news conference Wednesday, American actress and climate activist Jane Fonda accused Trump of making a "bargain with the devil" by embracing fossil fuels.

The US president has moved to slash environmental regulations since taking office this year, and has sought to withdraw the United States from the Paris climate accord.

"So we know whose side he's on. He's on the side of death, he's killing us and the nature that we depend on for our lives," Fonda said of Trump.