Countries at the COP29 summit in Baku adopted a $300 billion a year global finance target on Sunday to help poorer nations cope with the impacts of climate change, a deal its intended recipients criticised as woefully insufficient.

The agreement, clinched in overtime at the two-week conference in Azerbaijan’s capital, was meant to provide momentum for international efforts to curb global warming in a year destined to be the hottest on record.

Some delegates gave the deal a standing ovation in the COP29 plenary hall. Others lambasted wealthy nations for not doing more and criticised the Azerbaijan host for hurriedly gavelling through the contentious plan.

“I regret to say that this document is nothing more than an optical illusion,” Indian delegation representative Chandni Raina told the closing session of the summit, minutes after the deal was gavelled in. “This, in our opinion, will not address the enormity of the challenge we all face. Therefore, we oppose the adoption of this document.”

United Nations climate chief Simon Stiell acknowledged the difficult negotiations that led to the agreement but hailed the outcome as an insurance policy for humanity against global warming.

“It has been a difficult journey, but we’ve delivered a deal,” Stiell said. “This deal will keep the clean energy boom growing and protect billions of lives.

“But like any insurance policy, it only works if the premiums are paid in full, and on time.”

The agreement would provide $300 billion annually by 2035, boosting rich countries’ previous commitment to provide $100 billion annually in climate finance by 2020. That earlier goal was met two years late, in 2022, and expires in 2025.

The deal also lays the groundwork for next year’s climate summit, to be held in the Amazon rainforest of Brazil, where countries are meant to map out the next decade of climate action.

The summit cut to the heart of the debate over the financial responsibility of industrialised countries — whose historic use of fossil fuels has caused the bulk of greenhouse gas emissions — to compensate others for worsening damage from climate change.

It also exposed divisions between wealthy governments constrained by tight domestic budgets and developing nations reeling from the costs of storms, floods, and droughts.

Negotiations had been due to finish on Friday but ran into overtime as representatives from nearly 200 countries struggled to reach consensus. Talks were interrupted on Saturday as some developing countries and island nations walked away in frustration.

“We are leaving with a small portion of the funding climate-vulnerable countries urgently need. It isn’t nearly enough, but it’s a start,” said Tina Stege, Marshall Islands climate envoy.

Nations have been seeking financing to deliver on the Paris Agreement goal of limiting global temperature rise to 1.5° Celsius above pre-industrial levels — beyond which catastrophic climate impacts could occur.

The world is currently on track for as much as 3.1°C of warming by the end of this century, according to the 2024 UN Emissions Gap report, with global greenhouse gas emissions and fossil fuel use continuing to rise.

Sunday’s deal failed to set out detailed steps for how countries will act on last year’s U.N. climate summit pledge to transition away from fossil fuels and triple renewable energy capacity this decade. Some negotiators said Saudi Arabia had attempted to block such a plan during the talks.

“There’s definitely a challenge in getting greater ambition when you’re negotiating with the Saudis,” said US climate adviser John Podesta.

A Saudi official did not immediately provide comment.

What counts as a developed nation?

The roster of countries required to contribute — about two dozen industrialised countries, including the US, European nations and Canada — dates back to a list decided during UN climate talks in 1992.

European governments have demanded others pay in, including China, the world’s second-biggest economy, and oil-rich Gulf states. The deal encourages developing countries to make contributions but does not require them.

The agreement includes a broader goal of raising $1.3 trillion in climate finance annually by 2035 — which would include funding from all public and private sources and which economists say matches the sum needed to address global warming.

Countries also agreed on rules for a global market to buy and sell carbon credits that proponents say could mobilise billions more dollars into new projects to fight global warming, from reforestation to deployment of clean energy technologies. Securing the climate finance deal was a challenge from the start.

Donald Trump’s US presidential election victory this month has raised doubts among some negotiators that the world’s largest economy would pay into any climate finance goal agreed in Baku.

Trump, a Republican who takes office in January, has called climate change a hoax and promised to again remove the US from international climate cooperation.

President Joe Biden congratulated the COP29 participants for reaching what he called a historic agreement that would help mobilise needed funds but said more work was needed.

“While there is still substantial work ahead of us to achieve our climate goals, today’s outcome puts us one significant step closer. On behalf of the American people and future generations, we must continue to accelerate our work to keep a cleaner, safer, healthier planet within our grasp,” Biden said in a statement.

Western governments have seen global warming slip down the list of national priorities amid surging geopolitical tensions, including Russia’s war in Ukraine and the expanding conflict in the Middle East, and rising inflation.

The showdown over financing for developing countries comes in a year scientists predict will be the hottest on record. Climate woes are stacking up, with widespread flooding killing thousands across Africa, deadly landslides burying villages in Asia, and drought in South America shrinking rivers.

Developed countries have not been spared. Torrential rain triggered floods in Spain last month that left more than 200 dead, and the US so far this year has registered 24 billion-dollar disasters — just four fewer than last year.