British Prime Minister Boris Johnson on Friday appealed to richer countries to place more "cash on the table" to secure a climate breakthrough as the COP26 meeting in Glasgow slipped into overtime.

Poorer countries have balked at demands to do more to curb their own emissions, without promised financial support to transition away from fossil fuels and to adapt to the accelerating impacts of climate change.

The deadlock pushed COP26 past its scheduled end at 1800 GMT, with intense haggling expected through late Friday or even into the weekend.

But Johnson said that the Glasgow summit in itself would not be able to stop global warming.

"We won't clinch it all at COP, but we can start," he told reporters near London.

Delegates are charged with keeping the Paris Agreement temperature goals alive even as climate-driven disasters hit countries the world over
Delegates are charged with keeping the Paris Agreement temperature goals alive even as climate-driven disasters hit countries the world over AFP / Paul ELLIS

"We do need to see the cash on the table to help the developing world to make the necessary changes," he said. "That's what needs to happen in the next few hours."

Delegates from nearly 200 nations are tasked with keeping alive the 2015 Paris goal of limiting temperature rises to 1.5 degrees Celsius, as warming-driven disasters hit home around the world.

New wording to a draft COP26 agreement on Friday called for countries to accelerate "the phase-out of unabated coal power and of inefficient subsidies for fossil fuels".

That was softer than a first version of the text, but observers said the inclusion of the fuels driving the climate crisis was an important step.

"Unabated" coal plants are those that do not deploy carbon capture technology to offset some of their pollution.

The text requests countries to come back next year with updated climate pledges.

Climate Justice activist Vanessa Nakate addressed a plenary session at the COP26 UN Climate Change Conference in Glasgow on November 11, 2021. COP26 President Alok Sharma said there was still an array of unfinished business at the crunch UN climate summi
Climate Justice activist Vanessa Nakate addressed a plenary session at the COP26 UN Climate Change Conference in Glasgow on November 11, 2021. COP26 President Alok Sharma said there was still an array of unfinished business at the crunch UN climate summit AFP / Paul ELLIS

US climate envoy John Kerry said in Glasgow that fossil fuel subsidies -- including America's own -- were "insanity".

"We believe that this is existential," he told delegates.

"For many of you it is not existential in the future, it is existential today. People are dying today. All around the world the impacts are being felt, today."

The draft text also fleshes out a call for developed countries to "at least double" their funding for adaptation -- helping at-risk nations face climate impacts -- by 2025.

But a faultline remains over the failure of wealthy nations to meet their decade-old promise to provide $100 billion annually to help vulnerable nations prepare for the worst.

Kenyan environment minister Keriako Tobiko told delegates that failure to honour the funding pledge had severely hurt confidence.

Climate Justice activist Vanessa Nakate addressed a plenary session at the COP26 UN Climate Change Conference in Glasgow on November 11, 2021. COP26 President Alok Sharma said there was still an array of unfinished business at the crunch UN climate summi
Climate Justice activist Vanessa Nakate addressed a plenary session at the COP26 UN Climate Change Conference in Glasgow on November 11, 2021. COP26 President Alok Sharma said there was still an array of unfinished business at the crunch UN climate summit AFP / Paul ELLIS

"For myself, for Kenya, our trust has been shattered," he said, as more than 100 indigenous and other protesters marched through the summit venue demanding the rich world honour its promises.

The two-week summit began with a bang as world leaders descended on Glasgow armed with a string of headline announcements, from a commitment to slash methane emissions to a plan to save rainforests.

But current national emissions cutting plans, all told, would lead to 2.7C of heating, according to the UN, far in excess of the Paris target.

In a speech to delegates, European Commission Vice President Frans Timmermans held up his mobile phone with a picture of his one-year-old grandson on screen.

"If we fail -- and I mean fail now in the next few years -- he will fight with other human beings for water and food. That's the stark reality we face," he said.

He said the goal of limiting global warming to 1.5C is "about avoiding a future for our children and grandchildren that is unlivable".

Negotiations received a shot in the arm on Wednesday when the United States and China -- the two largest emitters -- unveiled a joint climate action plan, although it was light on detail.

But Johnson's identification of the cash issue cuts to the core, with the rich West accused of creating climate change but now refusing to pay for its consequences.

Developed nations meanwhile favour a greater push on emissions reductions, something countries yet to fully electrify their grids -- and largely blameless for emissions -- feel is unfair.

Countries already battered by climate disasters such as record-breaking drought and flooding are also demanding they be compensated separately for "loss and damage".

"Rich nations treat climate finance as charity or a favour to placate developing countries into signing a compromised package of decisions," Harjeet Singh, senior adviser at Climate Action Network International, told AFP.

"We are talking about saving lives and undoing an injustice to build a safe future for all."