French president Emmanuel Macron was the first to admit the contrast between the festive atmosphere at the One Planet Summit he convened on Tuesday and the gravity of the situation it was addressing.

“We’re having a good time,” the French leader said when he opened the final session of the one-day conference. “But we are losing the battle.”

The summit occurred two years to the day after the conclusion of the Paris accord to fight global warming. Its chief goal was to secure financing for the transition to renewable energy.

Referring to a recent report by 15,000 scientists, Mr Macron said: “We are not going fast enough, and that is the tragedy. We committed to limiting the increase in temperature to 1.5 degrees. If we continue as we are it will be 3 or 3.5 degrees.”

He invited 164 guests, including heads of state and government, US billionaires and film stars, to lunch at the Élysée Palace, then took them on a boat ride down the river to the Seine Musicale concert hall, on the island west of Paris that long housed the Renault car factory. The boat, called Mirage, was supposed to illustrate possible alternatives to road haulage. The summit helped create a record-breaking 552km traffic jam leading into Paris.

Mr Macron said the summit was different from repeated conferences that burn up huge amounts of air fuel but never seem to tackle global warming. “We will not make a classic declaration, but a declaration of action,” he said.

Twelve international commitments or “Clim’acts” agreed at the summit included strategies for responding to extreme climate events, plans to protect natural resources, measures to encourage the use of clean electric cars and incitements to the financial sector to “decarbonise”.

Fossil fuels

Some 85 per cent of greenhouse gas emissions come from fossil fuels. Mr Macron called for an end to their use worldwide, and promised France would vote this year to cease all exploitation of petroleum and gas resources by 2040.

A “coalition of philanthropists” comprising 10 foundations, including those of Bill Gates and Richard Branson, promised to step up its commitment to fighting climate change. Mr Gates is to contribute an additional €600 million to help developing countries transition to renewable energy technologies. Mr Macron said France would provide another €400 million, to bring the sum to €1 billion .

Another coalition, of sovereign funds, comprising Norway, the United Arab Emerites, Kuwait and New Zealand, pledged to spend thousands of billions of dollars to finance the energy transition.

The conference did not agree on a financial transactions tax, which is favoured by Mr Macron to help finance the energy transition. The French leader said he would pursue the idea, already in practice in France, with his European partners next year.

Mr Macron also defended the idea of a European carbon tax that would be high enough to be dissuasive of at least €30 per tonne.

“We say, ‘put a big, fat price on carbon’,” Angel Gurria, the head of the Organisation of Economic Co-operation and Development, said to applause.

Way to hell

The conference brought together doomsayers and do-gooders, victims and hangers-on.

“The world is not on the way to heaven. It’s on its way to hell,” governor Jerry Brown of California said. The fires that have ravaged his state were a mere hint of “lethal heat waves” to come. “The migration problems in Europe are nothing to what they will be when the Mediterranean burns up,” he said.

Roosevelt Skerrit, the prime minister of the tiny Caribbean island of Dominica, said he had heard enough talk. “We have to operationalise the Paris agreement now. Otherwise countries like Dominica will disappear.”

The private sector has woken up to the fact that fighting climate change is good business, but governments are lagging, said Laurent Fabius, a former French foreign minister, who fathered the Paris accord. “If France, the World Bank and the UN are organising this meeting, it’s so we can see who is truly committed and who is taking a back seat.”

Haunt the summit

Though absent, US president Donald Trump seemed to haunt the summit. Mr Macron said: “We’re here today in part because many decided not to accept the decision of the federal American government to leave the Paris accord.”

He told CBS News: “The US did sign the Paris agreement. It’s extremely aggressive to decide on its own just to leave.”

Tuesday’s summit was Mr Macron’s follow-up to his “make our planet great again” speech on the night that Trump withdrew from the agreement. In the run-up to the conference Libération newspaper called Mr Macron an “ecolopportunist”, and Le Figaro asked snidely: “Is Emmanuel Macron the saviour of the planet?”

By rallying billions in financial support for the fight against global warming, Mr Macron proved the summit was more than a vanity project.