WORLD leaders warned on Thursday that time is running short for urgent and decisive action to prevent the worst effects of climate change, and blasted the United States for failing to support the efforts.

This came as the 30th United Nations Conference of the Parties (Cop30) got under way in Belem, Brazil, on the edge of the Amazon rainforest.

UN secretary-general Antonio Guterres opened the conference with harsh words for world powers who “remain captive to the fossil fuel interests, rather than protecting the public interest.”

Allowing global warming to exceed the key benchmark of 1.5°C, laid out in the Paris Agreement, would represent a “moral failure and deadly negligence,” Mr Guterres said, warning that “even a temporary overshoot will have dramatic consequences, every fraction of a degree higher means more hunger, displacement and loss.”

Brazil President Luiz Inacio Lula da Silva sought to mobilise funds from world powers to halt the destruction of tropical rainforests and advance the many unmet promises made at previous summits.

But there are only half the heads of state in attendance at Cop30 as there were at last year’s summit.

In a rousing speech, Lula warned that the “window of opportunity we have to act is rapidly closing” and said there was “no greater symbol of the environmental cause” than the Amazon rainforest.

Some 17 per cent of the Amazon’s forest cover has vanished in the past 50 years, swallowed up for farmland, logging and mining.

Leaders spoke in Belem as the UN weather agency announced that 2025 was on track to be the second-warmest year ever recorded.

The concentration of greenhouse gases in the atmosphere, which hit a record high last year, continued to rise in 2025, as did ocean heat and sea levels, said the World Meteorological Organisation reported on Thursday.

US President Donald Trump, who calls climate change a hoax and withdrew his country from the Paris climate accords, did not send any senior officials to Belem.

Without naming President Trump, Lula said: “Extremist forces fabricate falsehoods to gain electoral advantage and trap future generations in an outdated model that perpetuates social and economic disparities and environmental degradation.”

Indigenous groups also warned that Mr Trump’s inaction could embolden other countries to ignore the crisis.

“It pushes governments further toward denial and deregulation,” said Nadino Kalapucha, the spokesperson for the Amazonian Kichwa Indigenous group in Ecuador.

“That trickles down to us, to Ecuador, Peru, Argentina, where environmental protection is already under pressure.”