Integrating Biodiversity and Desertification into Climate Law – Indian Blog of International Law

Tejas Rao

The International Court of Justice’s (ICJ/Court) Advisory Opinion (Opinion) on climate change obligations marks a shift in how international law conceptualizes the relationship between climate, biodiversity, and land degradation. For the first time at this level of international jurisprudence, the Court explicitly recognized that obligations under the Convention on Biological Diversity (CBD) and the United Nations Convention to Combat Desertification (UNCCD) are “relevant to the protection of the climate system” and “contribute to ensuring the protection of the climate system as a whole” (paras 330, 334). This contributes to the growing call for Rio Synergies, the integrated implementation of the three Rio Conventions – the UNFCCC, CBD, and UNCCD, emerging out of the Earth Summit in 1992. This concept recognizes that climate change, biodiversity loss, and land degradation are interconnected challenges requiring coordinated solutions rather than the fragmented, sector-specific approaches that have dominated international environmental governance 

As Judge Tladi observes in his declaration, the climate change crisis addressed in this Opinion concerns “one of the most consequential issues in the history of the Court,” potentially affecting “the future of humanity as a whole.” This framing underscores why the Court’s recognition of Rio Synergies as a legal imperative, not merely a policy preference, represents a shift in international law.

This  arrives at a critical juncture. As we emerge from 2024’s “triple COP” year, where all three Rio Conventions held their conferences within three months, the world witnessed both the promise and frustration of fragmented environmental governance. While the Presidents of the three COPs called for “a united approach to climate change, desertification and biodiversity loss,” actual progress remained siloed.

The Court’s approach starts from an understanding and appreciation of Earth system science. By adopting the definition that the climate system comprises “the totality of the atmosphere, hydrosphere, biosphere and geosphere and their interactions” (para 75), the ICJ establishes that protecting biodiversity and combating desertification are not merely complementary to climate action but integral components of climate system protection itself. Although this framing has long been understood by the scientific community, it allows for a departure from the siloed approach that has characterized much of international environmental law since 1992.

The CBD’s Dual Climate Function

The Court’s treatment of the CBD reveals how biodiversity conservation serves climate objectives. As the Court notes, “ecosystem protection measures may simultaneously operate as climate change mitigation or adaptation measures” (para 127). This simultaneity is given legal texture through three specific pathways.

First, under Article 6 of the CBD, States must develop national strategies that “may encompass measures for mitigation of and/or adaptation to climate change” (para 328). The Court transforms this “may” into something more substantial by linking it to the Kunming-Montreal Global Biodiversity Framework’s call to “[m]inimize the impact of climate change and ocean acidification on biodiversity.” Second, the monitoring obligations under Article 7(c) extend to activities “which contribute to anthropogenic GHG emissions” (para 329). Third, and perhaps most significantly, the Court establishes that the biosphere, as a component of the climate system, includes “all ecosystems and living organisms” (para 325), creating a legal basis for treating ecosystem degradation as climate harm.

Judge Cleveland’s declaration provides crucial elaboration on this point. She emphasizes that “(f)orests, oceans, mangroves, wetlands and other ecosystems are the lungs of the earth. They play a crucial role in climate mitigation by removing or storing greenhouse gases (GHGs) from the atmosphere” (para 4). The Court also acknowledged various States’ obligations regarding carbon sinks, with Article 4 of the UNFCCC requiring parties to take the lead in mitigating climate change “by limiting their GHG emissions and enhancing their GHG sinks and reservoirs” (para 199). This creates binding obligations for States to protect forests and other carbon reservoirs as an integral part of their climate commitments.

Land as the Operational Link

The Court’s analysis of the UNCCD provides perhaps the most innovative contribution to Rio Synergies jurisprudence.

Article 4(2)(a) of the UNCCD requires an “integrated approach addressing the physical, biological and socio-economic aspects of the processes of desertification and drought,” with the Court clarifying that physical aspects include “climate variability and climate change” (para 333). Moreover, Article 8’s mandate for coordination with both the UNFCCC and CBD becomes, in the Court’s reading, a legal obligation for integrated implementation. By establishing that desertification affects “interrelated parts of the climate system” (para 332), the Court transformed land degradation from a discrete environmental problem into a climate change issue as a matter of law.

The Architecture of Integration

It is possible to argue that the Court makes suggestions for integration based on four principles.

First, the principle of mutual reinforcement holds that “environmental treaties, climate change treaties and relevant obligations under customary international law inform each other” (para 335). This creates an interpretive basis to read the conventions together rather than in isolation.

Second, the principle of non-exclusivity rejects arguments that climate treaties constitute lex specialis, finding “no indication that the climate change treaties are meant to apply while simultaneously excluding general customary international law or other treaty rules on the protection of the environment” (para 170). This keeps the door open for biodiversity and desertification obligations to inform climate duties.

Third, the Court applies a “stringent” due diligence standard that extends across convention boundaries, noting that “adaptation and mitigation measures available to States—and their ability to contribute to the prevention of significant harm—depend on the sharing of information” (para 285).

Finally, the Court’s recognition that States must account for ecosystem interactions when conducting environmental impact assessments (para 298) requires integrated assessment methodologies that cannot stop at convention boundaries. The ITLOS Advisory Opinion reinforced this approach, holding that “Any planned activity, either public or private, which may cause substantial pollution to the marine environment or significant and harmful changes thereto through anthropogenic GHG emissions, including cumulative effects, shall be subjected to an environmental impact assessment”.

A Critical Assessment

While groundbreaking in its recognition of interconnected obligations, the Court’s approach has limitations. Judge Yusuf’s separate opinion criticizes the “excessively formalistic approach” that fails to address the material realities of climate injustice. Judge Xue argues that the Court should have provided clearer guidance on how the principle of sustainable development shapes these integrated obligations, noting that “mitigation is not solely about temperature control” but concerns “human activities and the capabilities of States to manage such activities.” 

Judge Bhandari’s observation that the Court gives only passing treatment to the polluter pays principle (two brief paragraphs) highlights a missed opportunity to strengthen the accountability architecture for integrated climate action. These critiques suggest that while the Court has established the legal foundation for Rio Synergies, much work remains in developing its practical implications.

The Path Forward

The ICJ’s recognition of CBD and UNCCD obligations as integral to climate protection creates new legal possibilities for States seeking comprehensive responses to the planetary crisis. No longer can States claim compliance with climate obligations while ignoring biodiversity loss or land degradation.

As we approach UNEA-7 in December 2025 with its theme “Advancing sustainable solutions for a resilient planet”, the ICJ’s opinion provides the juridical foundation for institutional reforms that have long been discussed but rarely implemented. The Assembly’s focus on “coherent policies to implement environmental mandates and commitments, improve access and use of scientific data and knowledge sharing, and strengthen collaboration” directly echoes the Court’s integrated approach. The forthcoming Global Environment Outlook (GEO-7) will undoubtedly need to reflect this new legal reality of interconnected environmental obligations.

Looking ahead to 2026’s triple COP convergence, the ICJ’s opinion demands more than rhetorical commitments to synergy. It requires concrete institutional mechanisms that reflect the legal reality that protecting the climate system necessarily involves protecting biodiversity and combating land degradation. The challenge now lies in translating this legal clarity into the integrated governance structures our planet urgently needs. As States prepare for another intense year of environmental negotiations, the ICJ’s opinion stands as a legal beacon for Rio Synergies, providing the juridical foundation for the integrated environmental governance that can deliver a truly resilient planet for present and future generations.

(Tejas Rao is PhD Researcher at the University of Cambridge and Senior Manager at the Centre for International Sustainable Development Law. Alongside, he consults for various IGOs and NGOs and supports the LDC Group/HCVCs on issues of international law, environment and development.)