VATICAN CITY — When Pope Francis appeared on the balcony of the Apostolic Palace, where he delivers an address each Sunday, he was met by the usual cheers and by an unusual forest of bright green oversized paper leaves.

Had he been able to read what was written on the leaves — which he could not because he was too far away — the pope would have found quotes from “Laudato Si’,” or “Praise Be to You,” his encyclical on the environment published this month.

The leaves were among the colorful props carried by a hodgepodge of organizations — mostly religious or environmental — that marched to the Vatican on Sunday to thank the pope for his forceful message on climate change, and to demand that world leaders heed his call for environmental justice and climate action.

“We want the pope to know we’re behind him 100 percent,” said Tafara Dandadzi, a student in environmental law and governance at North-West University in South Africa, who came to Rome for the march and to take part in a seminar convened in part to bring together emerging leaders from various religious and geographic backgrounds to coordinate on climate action.

“There are people here from different backgrounds with a common purpose,” Dandadzi added. “I hope the pope knows that, and I hope that the political leaders meeting in Paris later this year know that, too.”

World leaders will meet in Paris in December for a United Nations summit meeting on climate change that aims to arrive at a comprehensive global accord binding nations to limit greenhouse gas emissions. The pope’s encyclical, which links the environmental crisis to economics and poverty, has been widely read as a call for political action in support of an accord.

The encyclical is hardly the first foray of a religious leader in the realm of the environment, but it comes at a time when there is greater consciousness — as well as division and debate — on what to do about climate change.

“Around the world the spirit of humanity is rising to recognize that we have to care for the earth, that there is a deep moral obligation,” said the Rev. Fletcher Harper, a US Episcopal priest and the coordinator of Our Voices, an interreligious campaign for climate action, which organized the march with an Italian Catholic development nonprofit organization, Focsiv.

Dozens of Italian and international organizations also took part in the demonstration, which brought hundreds of people to St. Peter’s Square.

“This pope is giving voice to a sentiment that is growing in all faiths around the world,” Harper said. “We need all people in leadership positions to go decisively on the record about the need for deep change.”

The encyclical is by far the most forceful contribution on the topic by a pope, who has the ear of more than 1 billion Roman Catholics. Francis’ personal warmth has endeared him to many outside his faith.

“It’s an amazing document that brings together environmental science, social justice and religious teaching and asks us to think about economic policies,” said Samantha Smith, the leader of the Global Climate and Energy Initiative at World Wildlife Fund International. At the heart of the encyclical is a powerful message “that the way we are living on the planet is not sustainable or equitable,” she said. “But it is also hopeful because it urges global mobilization.”

Sunday’s march reprised the spirit, albeit on a much smaller scale, of the People’s Climate March that brought 300,000 people to the streets of New York in September. And although Sunday’s march was staged at St. Peter’s Square, its message seemed to resonate beyond the Roman Catholic Church. Alongside nuns and priests and other Catholics were Buddhists and Hindus. Only Rome’s residents were conspicuously absent.

“I encourage the collaboration between people and associations of different religions for the promotion of an integral ecology,” Francis said, acknowledging the marchers and reprising some of his considerations in the paper.

The Rabbi Lawrence Troster, from Teaneck, New Jersey, one of the organizers of the march, also underscored the universality of the pope’s message. “ ‘Laudato Si’ is addressed to everyone,” he said. “It is trying to create a consensus among all people, and not leave such an important issues to a small group of policymakers, leaders or diplomats.”