ROME — Holding the official launch of Pope Francis’ eco-encyclical in the Vatican’s Synod Hall, where Pope Benedict XVI installed a battery of more than 1,000 solar panels in 2008, was intended to drive home the core message of the document: Combatting climate change and other ecological maladies is “one of the principal challenges facing humanity in our day.”

A leading climate researcher and member of the UN panel on climate change gave the pontiff an “A” for command of the subject.

“The science of Laudato Si is watertight,” said Hans Joachim Schellnhuber, founding director of the Potsdam Institute for Climate Impact Research.

Also on hand to present the encyclical were a Catholic cardinal, an Orthodox metropolitan, and an American Catholic expert in business ethics.

The four underscored one of the hot-button issues addressed by the encyclical: climate change is happening, humans are partly responsible, and the time to act is now.

Orthodox Metropolitan John Zizioulas described Laudato Si as “food for thought for scientists, economists, the faithful of the Church, and all people of goodwill.”

“In the perspective of the encyclical – and of the Church – it is sufficient to say that human activity is one of the factors that explains climate change,” said Cardinal Peter Turkson of Ghana, president of the Vatican’s Pontifical Council for Justice and Peace.

“We therefore have a serious moral responsibility to do everything in our power to reduce our impact and avoid the negative effects on the environment and on the poor,” Turkson said.

At the request of Francis, Turkson was involved in the drafting process of Laudato Si. He called for an honest and open debate, so that “particular interests or ideologies don’t prejudice the common good.”

The Rev. Federico Lombardi, Vatican spokesman, said that the intense and prolonged interest in the papal document demonstrated its relevance.

Trying to put an end to the rumors circulating in Rome over how many ghostwriters were involved in compiling the encyclical, Lombardi said the document was personally written by Pope Francis, yet “not in solitude, but with the collaboration of many people.”

Lombardi said that Catholic bishops around the world have been receiving supplementary materials for the past month to aid in a proper understanding of Laudato Si and the pastoral task of explaining it to the faithful.

Thursday marked the first time in recent memory that an Orthodox cleric was asked to present a high-level papal document. Lombardi described Zizioulas’ presence as a “sign of common Christian commitment to safeguarding creation.”

Zizioulas thanked Pope Francis for “raising his authoritative voice to draw the world’s attention to the urgent need to protect God’s creation from the damage we humans inflict on it.” He said that in his opinion, the significance of Laudato Si’ is not limited to the subject of ecology.

“I see in it an important ecumenical dimension in that it brings the divided Christians before a common task which they must face together,” he said.

Zizioulas called for an ecumenical day of prayer for the environment to be held every Sept. 1. He explained that the Orthodox Church has been doing so since 1989, and said it could mark a step towards further closeness among the various Christian denominations.

Agreeing with Turkson, Zizioulas said a change in attitude must be achieved because “ecological sin is not only against each other, but against the future generations.”

With graphics and charts to back up his pitch, Schellnhuber said that if humanity fails to strongly reduce gas emissions and to curb global warming, “we, our neighbors, and children will be exposed to intolerable risks.”

Much in tune with Francis’ Laudato Si’, the scientist also said that the large-scale production of fossil fuel has led to great human development – but for only a minority: “On the other side of this development stand the poor and the poorest of the poor.”

Brandishing Francis’ text, Schellnhuber said he wanted to bring down “two myths” that surround climate change.

The first is that 85 of the richest individuals in the world own the same amount of wealth as 3.5 billion of the planet’s poorest people.

“It’s actually 60,” he deadpanned.

Schellnhuber said that the second myth he wanted to explode is that population control is required to address climate change.

“Contrary to what some have claimed, it is not the mass of poor people that destroys the planet, but the consumption of the rich,” he said.

Carolyn Woo, CEO and president of Catholic Relief Services and a former dean of
Notre Dame’s Mendoza College of Business, spoke from the perspective of the business world.

She said Laudato Si “can’t be dismissed because you don’t like the message,” adding that it’s based on solid science and that the truth is there for all to see: “We are harming the earth.”

Woo said that the encyclical affirms that business is a noble vocation, geared toward improving the world. Quoting from it, she said that “[the world] can be a source of prosperity …. especially if it sees the creation of jobs as an essential part of its service to the common good.”

Drawing most of her presentation from Francis, Woo underlined the importance of small businesses and diversified production. She also called for a restrain on monopolistic elements that constrain economic freedom, and for good governance and the rule of law.

“There is a positive role for business [described in the encyclical], but business must put the common good first,” Woo said.

Asked about the reaction the encyclical has generated among those who believe the pope shouldn’t talk about science because he’s not an expert, Turkson said he found that reaction “strange” because the environment is a topic of broad public interest.

“The fact is that we all talk about peace and war,” Turkson said. “We do so because we’re concerned by the impact they have on our lives. The fact that we’re not experts doesn’t mean we can’t talk about them.

“Every day we talk about things we’re not experts on!” he said.

Asked about US Catholic presidential hopefuls who have vowed not to listen to Francis on issues such as the environment and the economy, Turkson said that “it’s their freedom of choice that they can exercise.”

He joked that if the pope can’t talk about science because he’s not an expert, perhaps politicians shouldn’t do so either.