King Charles III told world leaders Friday that the UN's COP28 talks in Dubai must be a turning point in the fight against climate change, as tough negotiations on fossil fuels began.
King Charles kicked off two days of speeches by heads of state and government in the oil-rich United Arab Emirates, with a stark warning.
"We are carrying out a vast, frightening experiment... all at once, at a pace that far outstrips nature's ability to cope," he said.
"I pray with all my heart that COP28 will be another critical turning point towards genuine transformational action," added the king, a lifelong environmentalist.
The sense of urgency was heightened by a UN warning Thursday that 2023 is on track to become the hottest year on record, raising fears the world will not meet the goal of limiting warming to 1.5 degrees Celsius.
Brazilian President Luiz Inacio Lula da Silva hammered home the point, saying: "The planet is fed up with unfulfilled climate agreements."
More than 170 world leaders are due at COP28, but Chinese President Xi Jinping and US President Joe Biden -- whose countries are the world's biggest polluters -- are absent.
One by one, leaders acknowledged the threat posed by climate change, but most repeated existing pledges.
Developing nations spoke of the disproportionate impact of global warming on their people and urged wealthier nations to honour unfulfilled promises to deliver climate funding.
"Despite the fact that India is home to 17 percent of the world's population, our share of global carbon emissions is even less than four percent," Indian Prime Minister Narendra Modi said.
Chinese Vice Premier Ding Xuexiang said developed nations "should substantially scale up their support for developing countries in finance, technology and capacity-building."
The COP28 conference opened on Thursday with an early victory, the launch of a "loss and damage" fund for vulnerable countries devastated by natural disasters.
Observers hailed another breakthrough on Friday as more than 130 countries agreed to prioritise food and agriculture -- a big contributor to emissions -- in their climate plans.
More than 110 nations have also joined a call for tripling renewable energy and doubling energy efficiency by 2030, said European Commission President Ursula von der Leyen.
The Israel-Hamas war also cast a shadow over the conference, with the Iranian delegation walking out in protest over the presence of Israeli representatives.
- Phase down vs phase out -
Delegates face two weeks of tough negotiations on an array of issues that have long bedevilled climate talks, starting with the future of oil, gas and coal.
A first draft of a COP28 agreement being negotiated by nearly 200 countries includes language on a "phasedown/out" of fossil fuels, which account for the bulk of greenhouse gas emissions.
"The science is clear: the 1.5-degree limit is only possible if we ultimately stop burning all fossil fuels," UN Secretary-General Antonio Guterres said.
Activists have raised concerns about the influence of the energy industry lobby at COP28 as the conference is chaired by Sultan Al Jaber, who is also head of the UAE's national oil company.
Jaber, who is also chairman of a renewable energy firm, said Thursday the "role of fossil fuels" must be included in a final COP28 deal.
The draft text sets up a fight between those calling for a "phaseout" and those in favour of a less drastic "phasedown" of fossil fuels. But observers said the inclusion of such language was significant.
"It is more ambitious than anything ever tabled at COP27 (talks in Egypt last year), so even having it among the options is a big step up," said Lola Vallejo, an expert from French climate think tank IDDRI.
But Polish President Andrzej Duda, whose country relies on coal, warned that "people cannot bear additional costs for energy transition".
French President Emmanuel Macron said G7 rich nations "must set an example" for emerging countries by committing to exiting coal by the end of the decade.
- Gaza war -
But the climate crisis shared the spotlight with the Israel-Hamas conflict as a week-long truce ended, with the presidents of Cuba and Colombia calling the Gaza war "genocide".
"The incidents taking place in Gaza are a humanitarian crime, a war crime," Turkish President Recep Tayyip Erdogan said.
Israeli President Isaac Herzog met his UAE counterpart Sheikh Mohamed bin Zayed Al Nahyan on Thursday as part of a diplomatic push to release hostages held by Hamas since the conflict erupted on October 7.
Herzog left without addressing COP28.
