U.S. climate envoy John Podesta urged governments to keep faith in the country's promise to combat global warming, saying Donald Trump can slow, not stop, the transition from fossil fuels when he returns to office in January.

The annual U.N. climate summit began on Monday in Baku, Azerbaijan, with many country delegations concerned Trump's victory in U.S. presidential elections on Nov. 5 would hinder progress to limit planetary warming.

Trump has promised to again remove the United States, the world's biggest historic greenhouse gas emitter, from international climate cooperation and maximise the country's already record-high fossil fuel production.

"For those of us dedicated to climate action, last week's outcome in the United States is obviously bitterly disappointing," Podesta said at the summit.

"But what I want to tell you today is that while the United States federal government, under Donald Trump, may put climate action on the back burner, the work to contain climate change is going to continue in the United States."

He said the Inflation Reduction Act (IRA), President Joe Biden's landmark climate legislation providing billions of dollars in subsidies for clean energy, would continue to drive investments in solar, wind and other technologies, and that U.S. state governments would also push emissions cuts through regulation.

"I don't think that any of that is reversible. Can it be slowed down? Maybe. But the direction is clear," he said.

Although Trump has promised to rescind the IRA, to do so would require an act of Congress - and that could be elusive due to support from some Republican lawmakers whose districts benefit from IRA-linked investments.

AGENDA WRANGLING

Apart from the election of Trump as president of the world's biggest economy, the talks in Baku are vying for attention with economic concerns and wars in Ukraine and Gaza.

That complicates the summit's ambition to resolve the priority agenda item – a deal for up to $1 trillion in annual climate finance for developing countries, replacing a target of $100 billion.

U.N. climate chief Simon Stiell sought to whip up momentum.

"Let's dispense with the idea that climate finance is charity," he said at the Baku stadium. "An ambitious new climate finance goal is entirely in the self-interest of every nation, including the largest and wealthiest."

This year is on track to be the hottest on record. Rich and poor countries alike have been challenged by extreme weather events, including flooding disasters in Africa, coastal Spain and the U.S. state of North Carolina, drought gripping South America, Mexico and the U.S. West.

But even agreeing one of COP29's first tasks has proved a challenge: setting the the agenda for negotiations has been delayed for several hours.

Three sources with knowledge of the closed-door discussions, asking to remain anonymous, said the European Union and small island counties were demanding nations follow up last year's deal - including how to take forward its agreement to transition away from coal, oil and gas.

The Caspian Sea nation, which is home to the world's first oil wells, faces pressure to make progress on last year's COP28 pledge to transition away from fossil fuels.

But fossil fuel-producing Gulf states want to limit discussions to the elements of last year's COP28 deal related to finance, the sources said.

Countries were also at odds over a proposal from China to include trade on the COP29 agenda.

Trade has gained importance as an issue for China, already facing European Union tariffs, because of Trump's campaign promise to impose 20% tariffs on all foreign goods, and 60% on Chinese goods.

Many also worry U.S. disengagement could lead other countries to backpedal on existing climate pledges or scale back future ambitions.

"People will be saying, well, the U.S. is the second biggest emitter. It's the biggest economy in the world ... If they don't set themselves an ambitious target, why would we?" Marc Vanheukelen, the EU's climate ambassador from 2019 to 2023, told Reuters.

Talks host Azerbaijan has lobbied governments to accelerate their move to clean energy while touting gas as a transition fuel.

Its oil and gas revenues accounted for 35% of its economy in 2023, down from 50% two years earlier. The government says these revenues will decline to 22% by 2028.

President Ilham Aliyev has called Azerbaijan's fossil-fuel bounty "a gift of God," and Baku has proposed creating a Climate Finance Action Fund to collect voluntarily up to $1 billion from extractive companies across 10 countries including Azerbaijan.