GLASGOW, Scotland — The U.N. climate summit in Glasgow opened Sunday with appeals for action and prayers, kicking off two weeks of intense diplomatic negotiations by almost 200 countries on how to tackle the common challenge of intensifying global warming.

Following the opening gavel Sunday, leaders from around the world will gather in Scotland’s biggest city Monday to lay out their countries’ efforts to curb greenhouse gas emissions and deal with the effects of climate change. At the Vatican Sunday, Pope Francis appealed to the world’s people to pray that world leaders’ realize the suffering of the Earth and the poor as the climate warms.

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 newly opened summit remains “our last, best hope to keep 1.5 in reach,” said Alok Sharma, the British government minister chairing the Glasgow talks, known as COP26.

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 at the opening ceremony. “We can seize the enormous opportunities for green growth for good green jobs, the cheaper, cleaner power.”

He 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.

In Italy, the pope noted that it was the first day of the crucial gathering in Glasgow. He told the crowd gathered at 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.

“May this encounter yield efficient answers offering concrete hope to future generations,” the pope said. Francis has made care for the planet’s fragile environment a key plank of his papacy.

In Rome on Sunday, leaders of the G-20 nations accounting for 75% of greenhouse emissions were negotiating on what commitments they’re willing to make to contain rising global temperatures.

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. The United States is currently the world’s second biggest climate polluter, though historically it is responsible for the biggest amount of carbon dioxide in the atmosphere.

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.

“We need all of the G20 to come forward,” said Sharma. “The G20 represents 80% of global emissions and that’s why every country matters, but the G20 matters particularly.”

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.

Also speaking in Rome Sunday, Prince Charles urged world leaders to heed the “despairing voices” of young people who will bear the brunt of climate change.

The heir to the British throne described the talks in Glasgow as “literally the last-chance saloon” for the Earth.

Charles told Group of 20 leaders that they have an “overwhelming responsibility to generations yet unborn.”

“It is impossible not to hear the despairing voices of young people who see you as the stewards of the planet, holding the viability of their future in your hands,” he said.

On Monday, Charles is due to welcome leaders in Glasgow. His 95-year-old mother Queen Elizabeth II was due to attend but has been advised to rest by her doctors.

The opening day of the talks is expected to focus on procedural issues. One big worry 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.

The outgoing president of the meeting, Chile’s Carolina Schmidt, started the talks by asking officials to observe a minute’s silence for those who have died due to the coronavirus pandemic since the last U.N. climate conference was held in Madrid in late 2019, shortly before the outbreak began.

Jill Lawless in Rome, Ellen Knickmeyer in Glasgow and Silvia Hui in London contributed to this report.