Pope Leo XIV Must Follow in Francis’ Footsteps and Stand up for the Environment and Against Nuclear Weapons

Pope Leo XIV has been elected as the new leader of the Catholic Church. The new Pope will have big shoes to fill. The sheer humanity of Pope Francis—who embraced the poor and downtrodden, comforted the sick, and worked tirelessly to help the victims of wars, from Gaza to Sudan, from Ukraine to the Democratic Republic of the Congo—will be hard to match. By all accounts, Pope Leo XIV will find his own way and his own voice as the new pontiff. At this critical moment, he must also follow in his predecessor’s footsteps to protect our planet from destructive human activities, including the launch of nuclear war.

Pope Francis left a mark on the Church and the world in a way that previous papacies may not have, and not only for the ease of communication and the endless access to his writings, photos, and videos. Images of the Pope embracing Vinicio Riva, who was severely ill with a rare genetic skin condition, in 2013, or crossing St. Peter’s Square alone in the midst of the pandemic in 2020, were shared all across the globe. They became symbols of unconditional love, especially for those least fortunate, and of our joint pain amidst the worldwide upheaval wrought by COVID-19.

War to Pope Francis was always a crime against humanity, a violation of our dignity, and a failure of diplomacy.

His Holiness made the news in other ways. He furthered the conversations about the role of women in the church, LGBTQ belonging, priest celibacy, and more. Caught between those who pushed him to do more on these issues and those who scolded him for even raising them, the pontiff stuck to unity in the church, while keeping the conversations going, rather than shutting them down. He was unapologetic about deploring war, wherever it had taken its ugly roots, and eager to build bridges where connections were tenuous, including between the U.S. and Cuba. He spoke for humanity and for peace, regardless of prevailing narratives, popularity, or politics. War to Pope Francis was always a crime against humanity, a violation of our dignity, and a failure of diplomacy.

Perhaps less widely covered, but arguably with furthest reaching impact, were his stances on the environment and nuclear disarmament. They should be a part of his enduring legacy and must be positions that Pope Leo XIV embraces wholeheartedly. There are many reasons why we humans need to protect the environment and why we need to eliminate nuclear weapons. They range from security to economy to human health. But the moral reasoning is strong, and Pope Francis was a superb messenger of this critical argument. His message must live on and be embraced most forcefully not just by the new pontiff, but also other interfaith leaders.

In his 2015 Encyclical Laudato Si, Pope Francis called for universal responsibility of all members of the human family to care for one another, the Earth and all creatures on it. Covering topics such as pollution, climate change, the issue of water, and the loss of biodiversity, Pope Francis seamlessly alternated between scientific evidence and ethical reasoning. He highlighted the human impact on the environment and other Earth inhabitants from the emissions of greenhouse gases that arise primarily from burning of fossil fuels, and that have warmed the globe by more than one degree Celsius over the past several decades. Speaking of the loss of species and the human role in the destruction of their ecosystems, such as forests and woodlands, the Pope wrote, “Each year sees the disappearance of thousands of plant and animal species which we will never know, which our children will never see, because they have been lost forever. The great majority become extinct for reasons related to human activity. Because of us, thousands of species will no longer give glory to God by their very existence, nor convey their message to us. We have no such right.” Here was not just an argument based on self-preservation, ecosystem services provided to humans by intact nature, or dependence of future discoveries on conservation of existing ecosystems. Here was an argument that reached into the very essence of what it means to be human.

Francis understood that it’s not enough to just talk about these topics, but that action was sorely needed, from activities of well-meaning individuals to negotiations in the halls of the United Nations, and everywhere in between.

Pope Francis condemned nuclear weapons—even their existence, thereby introducing an urgent moral argument into the geopolitical considerations of all states, and most especially those that retain or rely on nuclear weapons for so-called security. He challenged the widespread notion that nuclear weapons keep us safe, arguing instead that the mere possession of these uniquely dangerous arms is immoral. He stated so in a Vatican conference in 2017, and then again in 2019, while visiting Hiroshima. He was a staunch supporter of the Treaty on the Prohibition of Nuclear Weapons (TPNW), a UN treaty that aims to eliminate all nuclear weapons from the face of the Earth. In fact, Holy See was the first States Party to the treaty, having signed and ratified it on September 20, 2017, the very first day that the TPNW was opened for signatures. In his message to the President of the First Meeting of States Parties, in June of 2022, Pope Francis stated that “a world free of nuclear weapons is both necessary and possible,” furthermore referring to existing disarmament treaties as “moral commitments.” He was supportive of not only the treaty’s elimination clauses, but also of its humanitarian provisions for victim assistance and environmental remediation. “Here my thoughts go to the Hibakusha, the survivors of the bombing of Hiroshima and Nagasaki, and to all the victims of nuclear arms testing,” the Pope emphasized, putting on display his seemingly boundless empathy.

Of course, Pope Francis did not bring these topics to the Catholic Church. From other Popes, to major Catholic thinkers, to dedicated clergy, Church leaders and followers have a long history of contributing to discourse on existential threats to planetary life, including from nuclear weapons. But the Pope set these topics ablaze during his time at the helm of the Catholic Church. On nuclear weapons, he did not equivocate or fall under the false spell of nuclear deterrence. He saw nuclear weapons for what they are, and he told us so in no uncertain terms, thus changing the Church’s official stance on nuclear weapons. Francis understood that it’s not enough to just talk about these topics, but that action was sorely needed, from activities of well-meaning individuals to negotiations in the halls of the United Nations, and everywhere in between.

There is much that Pope Leo XIV can do to advance a better world. But on the environment and nuclear weapons, following the path that Pope Francis blazed will be essential. Other religious and spiritual leaders should join him–as should we all.