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 Donald 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 and the US has sent 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 in an era of fake news and misrepresentation and rejection of scientific evidence.
Without naming President Trump, President Lula continued, they control the algorithms, sow hatred and spread fear.
It's time to inflict a new defeat on the deniers, he said.
Since President Trump took office in January, he has promised to invest heavily in fossil fuels, saying that this will secure greater economic prosperity for the US.
His administration has cancelled more than $13bn of funding for renewable energy and is taking steps to open up more areas of the US to oil and gas exploration.
This backdrop has put the COP talks in a difficult position as nations aim to make progress on tackling climate change without the participation of the world's biggest economy.
Addressing officials in Belém, UN climate chief Simon Stiell initially struck an optimistic tone. He said significant progress had been made in the last decade to reduce emissions of planet-warming gases.
But then he took aim at squabbling between countries and stated, Not one single nation among you can afford this, as climate disasters rip double-digits off GDP.
Brazil wants to use its presidency of the talks to secure progress on key promises made in previous years, including moving away from fossil fuels, finance for developing countries, and protecting nature.
President Lula's centerpiece is a fund called the Tropical Forest Forever Facility (TFFF) that Brazil hopes will raise $125bn to protect tropical forests globally.
Fund-raising got off to a slow start. Last week UK Prime Minister Keir Starmer said that the UK would not contribute public money.
However, on Monday, UK climate envoy Rachel Kyte stated that the fund was a brilliant idea and that the UK will make the investment at some point.
After lengthy discussions, nations finally agreed on a conference agenda, promising to consider the question of keeping global temperature rise to 1.5C above pre-industrial levels.
In recent weeks, even the UN has acknowledged that overshooting this temperature is inevitable.
UN Secretary-General António Guterres recently referred to the failure to limit global warming as a moral failure and deadly negligence.
