The US will be “central” to solving the climate crisis despite Donald Trump’s withdrawal of government support and cash, the president of the next UN climate summit has said.

André Corrêa do Lago, president-designate of the Cop30 summit for the host country, Brazil, hinted that businesses and other organisations in the US could play a constructive role without the White House.

“We have no idea of ignoring the US,” he told journalists on a call on Friday. “The US is a key country in this exercise. There is the US government, which will limit its participation [but] the US is a country with such amazing technology, amazing innovation – this is the US that can contribute. The US is a central country for these discussions and solutions.”

Brazil has also vowed to hold an “ethical stocktake” aimed at examining climate justice issues, for poor and vulnerable people, and to give Indigenous people a key role at the talks.

Corrêa do Lago wrote to all UN countries on Monday, setting out Brazil’s expectations that all governments will draw up national plans for steep cuts in greenhouse gas emissions before the conference starts in Belém, a rainforest city at the mouth of the Amazon, in November.

“Cop30 will be the first [summit] to take place at the epicentre of the climate crisis, and the first to be hosted in the Amazon, one of the world’s most vital ecosystems, now at risk of reaching an irreversible tipping point, according to scientists,” the letter said. “Change is inevitable, either by choice or catastrophe.”

As well as the formal negotiations at the summit in which only national governments can take part, there will be forums for regional and local governments – including those from the US – and for businesses and investors. Corrêa do Lago said these would be essential for progress because the Cop should involve an ongoing process of implementing climate action, rather than simply a focus on two weeks of technical negotiations.

“There is a perception these Cops are just about negotiation,” he said. “But we believe that accelerating implementation [of previously agreed actions] is very important. Let’s see how we can accelerate what we have already agreed.”

Brazil faces one of the worst geopolitical situations of any “conference of the parties” (Cop) since the UN framework convention on climate change, parent treaty to the 2015 Paris agreement, was signed in 1992. Trump has not only begun the process of withdrawing the US from the Paris accord, but is also rescinding climate finance pledged to the developing world, and dismantling federal support for climate science.

Trump’s response to Russia’s invasion of Ukraine, and the resulting rearmament of Europe which is under way, have left the developed world in turmoil. Many developing countries are concerned that they will be left further behind, amid the wrangling of the biggest economies.

Ana Toni, chief executive of Cop30, pointed to the outcome of the recently reconvened conference of the parties to the UN convention on biological diversity, which produced agreement on a plan to finance nature protection. “It was a really challenging moment, but we did see agreement,” she pointed out.

Many investors and businesses were expressing an interest in Cop30, she added. “We need to ensure [country’s emission-cutting] plans are investable and implementable,” she said. “We have had some very, very positive engagement with investors so far. They know the transition [to a low-carbon economy] is inevitable, and are looking for places where investments can be made.”

As well as setting out why stiff emissions cuts are needed, and urging governments to take drastic action to avoid climate catastrophe, Brazil’s letter to all governments pointedly referred to the spirit that defeated the Nazis in the second world war. Quoting Hannah Arendt, the philosopher who studied Hitler and his associates, it said: “Arendt denounced the ‘banality of evil’ as the acceptance of what was unacceptable. Now, we face the ‘banality of inaction’, an irresponsible and unacceptable inaction.”

The letter also invoked the Brazilian concepts of “mutirão”, which comes from the Tupi-Guarani language, and refers to a community coming together to work on shared task, and “virada”, which means fighting back in a game when defeat seems almost certain.