As the world’s attention turned to Belém, Brazil, in November 2025 for COP30, the United Nations’ annual climate change conference, an unprecedented convergence of faith, law, and diplomacy unfolded. The Catholic Church, more visible and vocal than ever before at a COP summit, joined a chorus of global actors grappling with the fallout from a groundbreaking legal development: the International Court of Justice’s (ICJ) landmark advisory opinion on climate change, released just months prior. Together, these forces shaped a summit marked by hope, tension, and the unmistakable sense that the rules of global climate action are shifting—if not always in ways that everyone agrees on.
The Catholic delegation to COP30 was notably robust, comprising eight members, including Bishops Martin Laliberté of Trois-Rivières and Jon Hansen of Mackenzie Fort-Smith. Their presence, as reported by The Catholic Register, reflected the Church’s deepening commitment to climate advocacy. Cardinals Jamie Spengler, Fridolin Ambongo, and Felipe Neri—presidents of the Continental Episcopal Conferences for Latin America, Africa, and Asia, respectively—were particularly active, building on their joint statement from June 12, 2025, titled “A Call for Climate Justice and the Common Home: Ecological Conversion, Transformation and Resistance to False Solutions.”
Inspired by this document, the delegation helped organize events aiming to foster dialogue between the Church in the global North and South. Bishop Jon Hansen, addressing a panel, remarked, “I’d like to thank the Canadian Conference of Catholic Bishops who sent both myself and Bishop Martin here…perhaps a small token to send two bishops, but it’s still an acknowledgement that we need to begin to talk about these things together, a historical coalition of north and south.” By the summit’s end, this coalition had coalesced into a unified voice—one that issued a statement representing five Cardinals, 23 bishops, and over 80 Catholic organizations from 30 countries present at COP30, with more than 300 organizations from 40 countries standing in solidarity.
The Church’s message, echoed throughout meals, panels, advocacy sessions, the Peoples’ Summit, Masses, and even a procession of the Virgem de Nazaré, was clear: ecological conversion is both a moral and spiritual imperative. Pope Leo XIV, in a message read by Cardinal Pietro Parolin, urged participants to “embrace with courage this ecological conversion in thought and actions, bearing in mind the human face of the climate crisis.” The Church’s call was rooted in the teachings of Pope Francis’s Laudato Si’, which famously urged humanity to heed both “the cry of the earth and the cry of the poor.”
Yet, as Catholic leaders and laypeople rallied for climate justice, another, more technical drama was unfolding in the negotiating rooms. The ICJ’s advisory opinion, released in July 2025, had determined that all states bear obligations to protect the climate system from significant harm. This legal milestone was quickly woven into climate litigation worldwide. According to The Wave, the Mexican community of El Bosque in Tabasco even used the opinion as leverage in negotiations over its national climate plan (NDC).
At COP30, a number of countries—including Monaco, Mexico, the Alliance of Small Island States (AOSIS), and the group of Least Developed Countries (LDCs)—pushed for the ICJ’s opinion to be recognized in official summit documents. However, as Earth Negotiations Bulletin’s Jennifer Bansard noted, these requests were “at very generic levels” and fell short of referencing the court’s actionable findings. The closest the ICJ advisory opinion came to formal acknowledgment was during a review of the Warsaw International Mechanism for Loss and Damage (WIM), a key mechanism for the new loss and damage fund.
The Independent Alliance of Latin American and Caribbean Nations (AILAC) advocated for the ICJ opinion as “an informed legal foundation” for advancing work on loss and damage, highlighting the need for comprehensive assessment, health protection for vulnerable groups, and forms of reparation. Vanuatu, which had led the diplomatic push for the ICJ opinion, supported this stance. But opposition was fierce. Saudi Arabia, representing the Arab Group, rejected the inclusion of the advisory opinion, stressing its non-binding nature and insisting that negotiations are a “party-driven process based on consensus, and not litigation.” The Arab Group reportedly described any mention of the ICJ opinion in the WIM document as a “deep, deep, deep red line,” with a Saudi negotiator warning, “If you insist on discussing it, we might as well just suspend this session to not waste each other’s time.”
Ultimately, the ICJ’s opinion was left out of the final WIM text. Harjeet Singh, founding director of the Satat Sampada Climate Foundation, explained that some countries, particularly major fossil fuel producers, were concerned that formally recognizing the opinion would open the door to “limitless legal liability for fossil fuel production.” The advisory opinion’s assertion that the status of a state as developed or developing “is not static” further fueled these anxieties.
Meanwhile, the opinion’s recognition of a “just and fast transition in line with best available science” was referenced by Fiji (for AOSIS) and others during negotiations on the Just Transition Work Programme. Malawi sought to frame transition finance as a legal necessity based on the opinion. Yet, despite these efforts, the final cover decision drafted by Brazil’s COP presidency omitted any reference to the ICJ’s findings, sticking instead to the familiar Paris Agreement language of “pursuing efforts” to limit warming to 1.5°C, while retaining the original “well below 2°C” target.
Some observers, like barrister Harj Narulla, argued that the COP30 decision “undermined” the ICJ’s conclusions. Insiders suggested that the absence of a coordinated push—particularly from the climate-vulnerable island nations that had championed the advisory opinion—was a key factor. Legal teams and government negotiators, it seemed, were not always on the same page about how to leverage the new legal framework. A briefing by Ed King and Lindsey Smith of the Global Strategic Communications Council characterized AOSIS’s efforts at COP30 as “insipid.”
Still, the advisory opinion’s influence was felt, if not seen in the official texts. Mohamed Adow, director of Power Shift Africa, told The Wave that the opinion was “starting to influence the wider narrative around responsibility and liability.” Harjeet Singh agreed, describing it as “the ‘undercurrent’ beneath many streams of negotiation.” Nikki Reisch of the Center for International Environmental Law said the opinion supports calls to reform the UNFCCC, including limiting fossil fuel industry influence and allowing majority voting to prevent a few countries from blocking action.
Looking ahead, the advisory opinion may loom even larger. In 2026, an international conference on a just transition away from fossil fuels—co-hosted by Colombia and The Netherlands—will align with the opinion’s findings, and experts expect a surge in domestic lawsuits citing the ICJ’s conclusions. As Nikki Reisch put it, “COP30 in Belém is by no means the last word on the ICJ AO or the climate duties it confirms.”
The Church’s call for ecological conversion and the ICJ’s assertion of legal responsibility may not have changed the letter of COP30’s outcome, but together they signal a growing convergence of moral, legal, and political will. In the Amazon’s humid air, the seeds of future climate action—rooted in faith and law alike—were unmistakably sown.