ROME— Insisting that environmental damage such as global warming amounts to a sin against creation, Pope Francis on Thursday once again called on Christians to join forces to protect the earth on what’s ecumenically designated as the “World Day of Prayer for Creation.”

“To commit a crime against the natural world is a sin against ourselves and a sin against God,” the pope writes, quoting an address the Ecumenical Patriarch Bartholomew gave in Santa Barbara, California, back in 1997.

Francis has long shared the interest for protecting the planet with Bartholomew.

In a message released by the Vatican on Thursday, Francis pointed out the “sins” against creation, which include humans destroying the ecosystem and degrading the integrity of the earth by causing changes in its climate, and the contamination of the earth’s waters, land, air, and life.

Keeping in mind both the Holy Year of Mercy and prayer day for creation, celebrated on Sept. 1, Francis on Thursday called for Catholics to add a new work of mercy to the traditional 14: “Care for our common home.”

The works of mercy, as taught by the Catholic Church, are divided into corporal and spiritual. The first seven, which include feeding the hungry, giving drink to the thirsty and clothes to the naked, were directly taken from the New Testament.

Yet in Thursday’s message, the pontiff proposes “a complement to the two traditional sets of seven.”

As a spiritual work of mercy, the care for our common home, Francis wrote, “calls for a ‘grateful contemplation of God’s world.” As a corporeal one, instead, it requires “simple daily gestures which break with the logic of violence, exploitation and selfishness” and “makes itself felt in every action that seeks to build a better world.”

The “World Day of Prayer for the Care of Creation” is a global ecumenical stewardship initiative, which began in 1989 under the leadership of the Orthodox Church. Yet it wasn’t until last year that the Catholic Church formally joined the initiative, with a letter from Francis establishing it.

In that August 2015 letter, the pontiff wrote that an annual commemoration of Creation would offer an opportunity to thank God for the “wonderful handiwork entrusted to our care, and to implore God’s help for the protection of creation,” an idea he reiterated in his latest pro-environment message.

The pope’s message titled “Show Mercy to our Common Home” is divided into five sections, and it’s largely an appeal for “people of faith and goodwill” to come together in “showing mercy to the earth as our common home and cherishing the world in which we live as a place for sharing and communion.”

As he did in his May 2015 environmental manifesto Laudato Si’, Francis once again says that global warming is at least partially man made, underlining that 2015 was the warmest year on record, and that 2016 will be warmer still.

Although some people remain skeptical, the scientific community has largely acknowledged that global warming due to pollution is leading to ever more severe droughts, floods, fires, and extreme weather events.

“Climate change is also contributing to the heart-rending refugee crisis,” Francis writes, adding that the world’s poor, though least responsible for climate change, “are most vulnerable and already suffering its impact.”

Francis also calls for the Jubilee of Mercy to summon in the faithful to a “profound interior conversion,” sustained by the sacrament of Confession, writing that after a “serious examination of conscience” Catholics can confess their sins against God and his creation.

The pope compared the need to make amends with the environment to Saint John Paul II’s 2000 appeal for Catholics to ask for forgiveness for past and present religious intolerance, “as well as for injustice towards Jews, women, indigenous peoples, immigrants, the poor and the unborn.”

“As individuals, we have grown comfortable with certain lifestyles shaped by a distorted culture of prosperity,” with a desire to consume more than what’s necessary, where “we are participants” in a system that has imposed a mentality of profit at any price.

“Let us repent of the harm we are doing to our common home,” Francis writes.

Examining our consciences, repentance and confession, the pope continues, will lead to a firm purpose to make amendments and take an attitude more respectful of creation.

Quoting his own Laudato Si’, something he does often in Thursday’s message, the pontiff gives several suggestions: “Avoiding the use of plastic and paper, reducing water consumption, separating refuse, cooking only what can reasonably be consumed, showing care for other living beings, using public transport or car-pooling, planting trees, turning off unnecessary lights, or any number of other practices.”

Calling on world leaders to uphold the Paris Climate Agreement and the United Nations Development Goals- and society to demand they be applied- the pontiff said that economics and politics, society and culture can’t be dominated by “short-term and immediate financial or electoral gains.”

“Instead, they urgently need to be redirected to the common good, which includes sustainability and care for creation,” Francis’ message says.

Christians of different denominations are marking the day of prayer for creation, although for many it’ll go until October 4th, the feast day of St. Francis of Assisi.

The pontiff is not the only Christian leader to release a message for the occasion. For instance, Orthodox Ecumenical Patriarch Bartholomew stressed the importance of education to highlight the links between the environmental crisis and the spiritual crisis of a world driven by greed, gluttony and selfish desires.

The general secretary of the World Council of Churches, Reverend Olav Fykse Tveit, sent a video message, calling for the world “obsessed by economic growth,” to radically rethink the ways of producing, trading and consuming natural resources.

“In a world where nearly everything has a price tag, it’s time for us to affirm once again that creation is not for sale,” he said.

Cardinal Peter Turkson of Ghana, appointed by Francis on Wednesday as the first head of a new super-department on human development, told a Vatican news conference that Francis’ message on Thursday is the “next logical step” after Laudato Si.

Turkson suggested, among other things, that Christians should use their purchasing power to boycott certain companies or products until they rethink their environmental footprint.

Terrence Ward, an author on hand for Thursday’s news conference, called Laudato Si one of the most important papal documents of modern times, saying it is “a breathtaking moral, social, economic and spiritual commentary on our modern epoch, fundamentally questioning our style of life.”

Ward suggested that the concrete work of mercy called for by the pope is an important contribution to the pope’s Year of Mercy.