The world must defeat climate denialism and fight fake news, Brazil's President Luiz Inácio Lula da Silva has told the opening meeting of the UN climate talks.

In a rallying cry to COP30, President Lula again made thinly veiled references to President Trump, who branded climate change a con job in September.

The two weeks of talks kicked off on Monday in the lush Brazilian city of Belém on the edge of the Amazon rainforest.

They take place against a fraught political backdrop, with the US sending no senior officials.

On Monday, thousands of delegates poured into the COP venue in a heavily air-conditioned former aerodrome, some coming from accommodation in shipping containers and cruise ships moored on the riverside.

Members of the Guajajara indigenous group, in traditional dress, performed a welcome song and dance for assembled diplomats.

Addressing the conference, President Lula said COP30 will be the COP of truth during an era of fake news and misrepresentation and the rejection of scientific evidence.

Without naming President Trump, Lula stated, they control the algorithms, sow hatred, and spread fear. He added, It's time to inflict a new defeat on the deniers.

Since President Trump took office in January, he has promised heavy investments in fossil fuels, which he claims will generate greater economic prosperity for the US. His administration has cancelled significant funding for renewable energy and aims to increase oil and gas exploration.

This position places the United States at odds with the majority of nations endeavoring to reduce greenhouse gas emissions and shift towards sustainable energy sources.

The absence of senior US officials complicates the COP talks, with fears that the US could still send representatives to disrupt proceedings, following an atmosphere of tension in previous environmental discussions.

Amidst the political difficulties, UN climate chief Simon Stiell balanced optimism regarding emissions reductions over the past decade with concerns about ongoing infighting among nations.

Brazil seeks to use its presidency of the talks to push for key commitments, including phasing out fossil fuels and securing financing for climate-affected developing countries. A prominent initiative of this summit is the Tropical Forest Forever Facility (TFFF), which aims to raise $125 billion for the protection of tropical forests worldwide.

While fundraising efforts began slowly, enthusiasm from international leaders appears to be increasing—UK climate envoy Rachel Kyte even endorsed the TFFF, indicating potential investment soon.

The conference agenda was approved on Monday, sparked particularly by calls from affected nations advocating for limits on global temperature rise, while recognizing that exceeding 1.5C may become unavoidable.