BELEM, Brazil >> A litany of recent weather disasters rang long Monday at the opening of U.N. climate negotiations: Hurricane Melissa in Jamaica, a deadly tornado in Brazil, droughts and fire in Africa. Against that backdrop, activists used an empty chair to drive home the absence from these talks of the United States, the world’s richest nation and second-biggest carbon polluter.

World leaders highlighted the devastation wrought on some of the world’s poorest places to show the need to work collectively to fight global warming, which is fueling extreme weather. But any united front will be without the U.S., one of only four nations missing the talks, along with tiny San Marino and strife-torn Afghanistan and Myanmar.

The 195 nations who did come to Belem, a weathered city on the edge of the Brazilian Amazon, for the talks known as COP30 were told that only together can they swiftly reduce the emissions from coal, oil and gas that cause climate change.

While the activists’ empty chair primarily illustrated the U.S. absence, it was also intended to be a call-out for other nations “to step in and step up,” Danni Taaffe with Climate Action Network International said.

Those leading the talks sounded a similar note.

“Humanity is still in this fight. We have some tough opponents, no doubt, but we also have some heavyweights on our side. One is the brute power of the market forces as renewables get cheaper,” United Nations climate secretary Simon Stiell said.

Brazil President Luiz Inácio Lula da Silva, whose nation is hosting these talks, urged negotiators not to forget that “the climate emergency is an increase of inequality.”

“It deepens the perverse logic that defines who is worthy of living and who should die,” Lula said.

This year’s talks are not expected to produce an ambitious new deal. Instead, organizers and analysts frame this year’s conference as the “implementation COP.” Countries had a clear mandate: arrive with their updated national plans to fight climate change.

On Monday, the United Nations released updated calculations showing that those national pledges promise to reduce projected 2035 global greenhouse gas emissions 12% below 2019 levels. That’s 2 points better than last month, before new pledges rolled in.

Attendees on Monday stressed cooperation, with Stiell saying that individual nations simply cannot cut heat-trapping gas emissions fast enough on their own.

André Corrêa do Lago, president of this year’s conference, emphasized that negotiators must engage in “mutirão” — a local Indigenous term that refers to a group uniting to complete a task.

Complicating those calls is the absence of the United States, where U.S. President Donald Trump has long denied the existence of climate change.