World leaders and delegates gathered Thursday in the Amazonian city of Belem for the opening of COP30, where U.N. Secretary-General António Guterres warned that the world has “failed to ensure we remain below 1.5 degrees” of global warming.

He called the moment a “moral failure and deadly negligence,” urging nations to act quickly to curb emissions and avoid irreversible climate tipping points.

Brazilian President Luiz Inácio Lula da Silva stressed on Thursday it was time world leaders "take scientific warnings seriously" as he opened the COP30 conference in the Amazon city of Belem.

"It's time to face reality and decide whether we have the courage and determination needed to change it," he told those gathered for the start of the climate summit.

Those descending on the United Nations annual climate summit in Brazil this week will not need to see much more than the view from their airplane window to sense the unfathomable stakes.

Surrounding the coastal city of Belem is an emerald green carpet festooned with winding rivers.

But the view also reveals barren plains: some 17% of the Amazon's forest cover has vanished in the past 50 years, swallowed up for farmland, logging and mining.