Thousands of Catholics joined in climate strikes on Friday, following the lead of 16-year-old Greta Thunberg, the Swedish climate activist who ignited the global movement, but also that of 82-year-old Pope Francis who has made environmental concerns a centerpiece of his papacy.

Across the globe, an estimated four million individuals - including a sizable number of school kids who skipped classes and took to the streets - banded together to demand that governments and corporations take actions to reduce carbon emissions to stave off a climate disaster.

Christina Leaño, associate director of Global Catholic Climate Movement which helped bring together several hundred Catholic marchers in New York on Friday, told Crux that Catholics were present to give lived witness to Laudato si’, Francis’s 2015 landmark encyclical calling for urgent attention to the environment.

“We are in the middle of a climate emergency, and people of faith need to respect all life, including generations to be born, all living species on the planet, and the children living now,” said Leaño.

She went on to note how Laudato si’ calls for “intergenerational solidarity” between the young and the old and said that Friday’s climate strike was an example of just that.

“There’s no better way to express that intergenerational solidarity than with those who should not have to be out here skipping schools to fight for their lives,” Leaño said.

In the nation’s capital, Father Jacek Orzechowski, who works in parish community organizing and advocacy through Catholic Charities of the Archdiocese of Washington, said that he was marching in hopes that it would inspire more Catholics to follow the pope’s example.

“Overall the Church in the United States has been anemic and inadequate to say the least,” Orzechowski told Crux, in assessing the U.S. Church’s response to Laudato si’.

“We have a heightened responsibility to lead and provide moral leadership on this most pressing, social justice and pro-life issue that we face, yet we have done little to follow in the example of Pope Francis to make this issue a priority.”

Leaño, however, pointed to the work of the Archdiocese of Chicago, the Sisters of Mercy, the Ignatian Solidarity Network, and the Maryknoll Sisters, as examples of U.S. Catholic groups that are “all rising up” to provide leadership in caring for creation.

“We need to scale up,” Orzechowski insisted of U.S. Catholics, while also highlighting the many Catholic school children present on Friday who he said are “evangelizing us” with their presence during the climate strike.

Rafael Visoso, an 8th grade student at St. Francis International in Maryland, just outside of D.C., said that he was marching, along with about 40 other students from his school, who are inspired by their Catholic faith to join in the youth-led movement.

“There are many saints in our Church who have been role models in caring for the environment,” he told Crux. “And when people come together as one to demand action, anything can happen.”

Orzechowski said that given the Church’s recent scandals surrounding the clergy abuse crisis, he believed it was especially important for Catholics to show leadership in fighting climate change, describing this issue as a “litmus test” for the Church in the United States.

“Do we have the moral clarity to protect children of this generation and future generations?” he asked.

Erin Lothes, a theologian at the College of Saint Elizabeth in Morristown, New Jersey, who joined with the Metro NY Catholic Climate Movement, told Crux that she hoped the presence of so many Catholics at Friday’s march would inspire church leaders to “bring environmental concerns into the sanctuary in a more visible way.”

The Catholic tradition has long had a “sacramental reverence for the earth as God’s creation,” Lothes continued, and for Catholics, the climate strike is one more way to “stand in solidarity with all of our brothers and sisters around the world,” adding that she hopes the event prompts an examination of conscience for the ways in which “our communities, our social lives, and our sanctuaries are dependent on fossil fuels.”

Ahead of Friday’s global protests, the 16-year-old Thunberg briefly met with Pope Francis at the Vatican in April where she told him, “Thank you for standing up for the climate, for speaking the truth. It means a lot.”

As she held a sign that read, “join the climate strike,” Francis encouraged her to “Continue, continue. Go on, go ahead.”

On Friday, she did just that, telling an estimated crowd of 250,000 in Manhattan that “right now we are the ones who are making a difference. If no one else will take action, then we will.”

“We demand a safe future,” Thunberg pleaded. “Is that really too much to ask?”