Focus at the COP26 summit turned Wednesday to how the world will pay for its ambitions to quit fossil fuels and help vulnerable nations survive climate change, as campaigners expressed scepticism over promises of billions from financiers and governments.

After a world leaders' summit yielded a landmark deal slashing methane emissions, negotiators are now tasked with keeping alive the Paris Agreement goal of limiting warming to 1.5 degrees Celsius.

But a simmering diplomatic spat between the United States, China and Russia over their climate action ambitions showed the fragile nature of talks aimed at averting disastrous global heating.

British Chancellor Rishi Sunak said that COP26 would finally deliver the funds needed by vulnerable nations
British Chancellor Rishi Sunak said that COP26 would finally deliver the funds needed by vulnerable nations AFP / DANIEL LEAL-OLIVAS

With funding crucial for turning climate pledges into reality, a financial coalition representing trillions in private capital made net-zero pledges on Wednesday.

COP26 president Alok Sharma said there was "big momentum" from the private sector.

But he acknowledged that governments of wealthy nations failed to honour a key pledge to help poorer nations green their energy grids and respond to increasingly extreme drought and flooding.

He told the conference it was "regrettable" that the decade-old vow to provide $100 billion annually had not been delivered by 2020 as promised and would likely not be met until 2023.

Atmospheric concentrations of the major greenhouse gases, carbon dixoide, methane and nitrous oxide, are at record levels
Atmospheric concentrations of the major greenhouse gases, carbon dixoide, methane and nitrous oxide, are at record levels AFP / Jonathan WALTER

Delays in the funding have reopened tensions between vulnerable nations, often the least responsible for emissions, and polluting richer countries.

"Climate finance in 2021 is as volatile as the strengthening storms that rip through the fabric of our economy year in year out," Fiji's Economy Minister Aiyaz Sayed-Khaiyum told the conference, adding it was still unclear in what form the money would come in.

"How many years until we wake up and realise that we have built a system that actually destroys the planet by design," he said, slamming continuing subsidies for fossil fuels.

Negotiators are in Glasgow to try to keep the Paris Agreement temperature goal of 1.5C within reach
Negotiators are in Glasgow to try to keep the Paris Agreement temperature goal of 1.5C within reach AFP / ANDY BUCHANAN

But former Bank of England governor Mark Carney told the conference the global financial system "has been transformed to deliver net zero".

With billionaire businessman Michael Bloomberg, he is spearheading an initiative by a group of 450 banks, insurers and pension funds with $130 trillion in assets to help countries achieve carbon neutrality.

Carney said the Glasgow Financial Alliance would help the world reach net-zero emissions by 2050 "at the latest".

A string of protests are planned during COP26 to push leaders to deliver
A string of protests are planned during COP26 to push leaders to deliver AFP / ANDY BUCHANAN

US Treasury Secretary Janet Yellen told the conference mobilising private capital was "essential".

"No amount of public financing alone will be sufficient to meet the demands of the climate crisis," she warned.

But campaign groups reacted with scepticism, pointing out that funds involved were still investing heavily in oil and gas.

"The commitments they have made are so full of loopholes, that there is plenty of space for some of the worst financiers of the worst polluters on the planet," said Kenneth Haar of the Corporate Europe Observatory.

UK finance minister pledges billions at COP26 to achieve net zero
UK finance minister pledges billions at COP26 to achieve net zero International Pool via Bloomberg

And on the streets of Glasgow, Extinction Rebellion and other activists responded to the COP26 finance-themed day with a protest against "Greenwashing".

"There's been too many words, not enough action," said one protester, Janet, dressed in a hard hat and high visibility jacket emblazoned with the slogan "build back greener".

Delegations will spend the coming days thrashing out details of the Paris Agreement rulebook, including rules governing carbon markets and a unified "stock take" on emissions cutting plans.

Although organisers say they want COP26 to keep the 1.5C heating limit within reach, the UN says the most up-to-date climate pledges put Earth on course to warm 2.7C.

British Prime Minister Boris Johnson told parliament on Wednesday that negotiations "have a long way to go".

"Whether we can summon the collective wisdom and will to save ourselves from an avoidable disaster still hangs in the balance," he said.

On Tuesday leaders committed to lower their emissions of methane -- a potent greenhouse gas -- by at least 30 percent this decade.

Experts said the pledge could have a significant impact on short-term heating.

But a two-day world leaders' summit ended with barbed comments from the two largest emitters, the United States and China.

US President Joe Biden criticised counterpart Xi Jinping for skipping the summit, after China declined to sign the methane pledge.

"It just is a gigantic issue and they walked away," Biden said before leaving Glasgow.

He said the same was true of Russian President Vladimir Putin, who is also missing the talks.

But China and Russia pushed back on that assessment.

"If we are to only focus on 1.5C, it means we are destroying this consensus between all parties," Xie said.