NAIROBI, KENYA – Just days before the opening of a UN climate change summit in Paris, Pope Francis on Thursday warned it would be “catastrophic” if global leaders taking part in the meeting fail to ratify significant reductions in the use of fossil fuels.

“Particular interests,” the pontiff insisted, should not be allowed to prevail over the common good in the fight against global warming and climate change. He also took an indirect shot at global warming skeptics, warning against “manipulating information” to serve someone’s “plans and projects.”

Francis was speaking at a United Nations campus in Nairobi, Kenya, on the second day of a Nov. 25-30 visit to Africa. Nairobi is the global headquarters for UN programs on both the environment and housing.

Also on Thursday, Francis called for deeper dialogue among religions, defended the Catholic concept of family and delivered a strong note of thanks to clergy and religious, including missionaries serving in Africa.

In his remarks to the United Nations, Pope Francis said the global leaders who will meet in Paris beginning next Monday are “confronted with a choice which cannot be ignored: either to improve or to destroy the environment.”

The 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (COP21), will take place Nov. 30-Dec. 11 in the French capital, with representatives from 194 countries.

US President Barak Obama is among the 147 heads of state and government scheduled to participate.

Francis called on the COP21 meeting to develop “a new energy system which depends on a minimal use of fossil fuels, aims at energy efficiency, and makes use of energy sources with little or no carbon content.”

“It would be sad, and I dare say even catastrophic, were particular interests to prevail over the common good and lead to manipulating information in order to protect their own plans and projects,” Francis said.

According to Francis, who in May published the first-ever papal encyclical dedicated to the environment, Laudato Si’, climate change represents one of the principal challenges facing humanity because it has environmental, social, economic, political implications.

Quoting his own document, Francis said that the response to the challenge needs to take into account the “fundamental rights of the poor and the underprivileged.”

“I express my hope that COP21 will achieve a global and ‘transformational’ agreement based on the principles of solidarity, justice, equality, and participation,” targeting three goals: “lessening the impact of climate change, fighting poverty, and ensuring respect for human dignity.”

Francis also called for education and training programs to foster a “culture of care” for both the poor and creation in place of “a culture of waste, a throw-away culture where people use and discard themselves, others and the environment.”

In a nod to a keen local concern, Francis also denounced ivory trafficking and the killing of elephants, saying it’s related to “political instability, organized crime, and terrorism.” According to Conservation International, one elephant is killed illegally in Africa every 15 minutes, which has brought the continent’s elephant population down from 10 million at the dawn of the 20th century to an estimated 400,000 today.

On Thursday morning, Francis met with 40 local Christian, Muslim, Buddhist, Jews, and Sikh leaders in an interreligious and ecumenical encounter, saying that inter-faith dialogue “is not a luxury.”

God’s “holy name,” he said, “must never be used to justify hatred and violence.”

The pope also said that religions need to work together in friendship to defend the God-given dignity of individuals and their right to live in freedom and happiness.

Mid-morning, Francis celebrated a Mass at the campus of the University of Nairobi, where a crowd estimated at 300,000 people turned up despite strong rain, braving both mud up to their ankles and disorganized security controls that made it difficult for many to reach the site.

Dismes Bukhala from Mombasa, for instance, told Crux he needed 48 hours to reach the capital, but nevertheless was in good spirits.

“How could I not come?” he said. “The pope is here!”

“I want for [the pope] to ask us to learn to coexist in peace, to have the promise of his prayer for us and his blessing,” Bukhala said. “But he brought us rain, so we have this already!”

Kenya’s economy is partially rooted in rain-fed agriculture, and according to Bukhala, global warming has made rain season unpredictable. “We need to eat, and for this, we need water.”

During his homily, the pontiff made a plea for traditional values, saying “the health of any society depends on the health of its families.”

“Our faith in God’s word calls us to support families in their mission in society, to accept children as a blessing of our world, and to defend the dignity of each man and woman,” Francis said.

In an indirect reference to abortion, he added, “we are also called to resist practices which foster arrogance in men, hurt or demean women, and threaten the life of the innocent unborn.”

As Americans celebrated Thanksgiving, Francis delivered a strong note of thanks to clergy and religious in a session at a Catholic school in Nairobi.

Speaking as he often does in such settings in improvised Spanish, the pope urged religious “to serve and not to be served,” quoting one elderly cardinal to the effect that all the missionaries and religious who give their lives in service “should be canonized tomorrow.”

“Thank you for following Jesus … for every caress of tenderness that you show those who need it,” he said. “Thank you for all the times you helped a person die in peace, thank you for giving hope in life, and for allowing yourselves to be forgiven, helped, and corrected every day.”

On Friday, Francis will visit a slum in the outskirts of Nairobi and meet with local youths before heading to Uganda, where he’ll address local leaders, a group of catechists and teachers, religious men and women, celebrate a Mass honoring the Ugandan Martyrs, and visit the House of Charity of Nalukolongo.

The last leg of the trip, scheduled to begin Sunday, will be the conflict-torn Central African Republic, where the pontiff is determined to travel despite a volatile situation result of clashings between Muslim and Christian militias.

According to L’Osservatore Romano, the Vatican’s newspaper, when he greeted the pilot that took him to Kenya, he said “I really want to go to the Central African Republic.”

“If you can’t take me there,” Francis added jokingly, “give me a parachute!”