GLASGOW, Scotland (AP) -- A crucial U.N. climate summit opened Sunday amid papal appeals for prayers and activists' demands for action, kicking off two weeks of intense diplomatic negotiations by almost 200 countries aimed at speeding up the global response to global warming.
As U.N. officials gaveled the climate summit to its formal opening in Glasgow, the heads of the world's leading economies at the close of their own separate talks in Italy made a commitment to cut pollution from burning coal and other fossil fuels. But the agreement was vague and not the major push some had been hoping for to give momentum to the climate summit.
Government leaders face two choices at the climate summit, Patricia Espinosa, head of the U.N. climate office, declared at the summit's opening: They can sharply cut greenhouse gas emissions and help communities and countries survive what is becoming a hotter, harsher world, Espinosa said. "Or we accept that humanity faces a bleak future on this planet."
"It is for these reasons and more that we must make progress here in Glasgow," Espinosa said. "We must make it a success."
India Logan-Riley, an Indigenous climate activist from New Zealand, had a blunt message for negotiators and world leaders at the summit's opening ceremony.
"Get in line, or get out of the way," Logan-Riley said.
In Rome at the end of the two-day G-20 summit, leaders of the world's biggest economies made a vague pledge saying they would to seek carbon neutrality "by or around mid-century." Shortly afterward, Russia made clear that it was sticking to its target of 2060 -- a decade later than the United States, the European Union and many others.
The Group of 20 leaders also agreed to end public financing for coal-fired power generation abroad, but set no target for phasing out coal domestically -- a clear nod to China and India.
The G-20 countries represent more than three-quarters of the world's greenhouse gas emissions and G-20 host Italy and Britain, which is hosting the Glasgow conference, had looked for more ambitious targets coming out of Rome.
Some climate activists said the pledges from the G-20 countries were far from enough.
"I don't think the G-20 provided the kind of leadership the world needs right now at this moment of climate crisis," Greenpeace Executive Director Jennifer Morgan told The Associated Press in Glasgow. "I think it was a betrayal to young people around the world."
While the opening ceremony in Glasgow formally kicked off the talks, known as COP26, the more anticipated launch comes Monday, when leaders from around the world will gather to lay out their countries' efforts to curb greenhouse gas emissions and deal with the mounting damage from climate change.
The leaders of three of the world's biggest climate polluters - China, Russia and Brazil -- were not expected to attend the summit, though seniors officials from those countries planned to participate. For U.S. President Joe Biden, whose country is the world's worst current climate polluter after China, the summit comes at a time when division within his own Democratic party is forcing him to scale back ambitious climate efforts.
At the Vatican Sunday, Pope Francis urged the crowds gathered in St. Peter's Square: "Let us pray so that the cry of the Earth and the cry of the poor" is heard by summit participants.
Negotiators will push nations to ratchet up their efforts to keep global temperatures from rising by more than 1.5 degrees Celsius (2.7 Fahrenheit) this century compared with pre-industrial times.
The climate summit remains "our last, best hope to keep 1.5 in reach," said Alok Sharma, the British government minister chairing climate talks.
Scientists say the chances of meeting that goal, agreed to in the landmark deal closed at the 2015 Paris climate accord, are slowly slipping away. The world has already warmed by more than 1.1C and current projections based on planned emissions cuts over the next decade are for it to hit 2.7C by the year 2100.
The amount of energy unleashed by such planetary warming would melt much of the planet's ice, raise global sea levels and greatly increase the likelihood and intensity of extreme weather, experts warn.
"We can move the negotiations forward and we can launch a decade of ever increasing ambition and action," Sharma said. "We can seize the enormous opportunities for green growth for good green jobs, the cheaper, cleaner power."
U.S. climate envoy John Kerry warned last week of the dramatic impacts that exceeding the 2015 Paris accord's goal will have on nature and people, but expressed optimism that the world is heading in the right direction.
Sharma noted that China, the world's biggest emitter of greenhouse gases, had just raised its climate targets somewhat.
"But of course we expected more," Sharma told the BBC earlier Sunday.
India, the world's third biggest emitter, has yet to follow China, the U.S. and the European Union in setting a target for reaching 'net zero' emissions. Negotiators are hoping India's Prime Minister Narendra Modi will announce such a goal in Glasgow.
Some of the issues being discussed during the talks have been on the agenda for decades, including how rich countries can help poor nations tackle emissions and adapt to a hotter world. The slow pace of action has angered many environmental campaigners, who are expected to stage loud and creative protests during the summit.
One big worry at the talks is that not all the delegates will be able to meet in person, as the venue and room capacities have been limited due to COVID concerns.
Meanwhile, hundreds of passengers hoping to reach the summit in a climate-friendly way were stuck in London after a fallen tree halted train services to Scotland. Train operator Avanti West Coast said it was advising customers not to travel.