Introduction
Climate change represents one of the most pressing global challenges of the 21st century, transcending national boundaries and necessitating unprecedented international cooperation. The Paris Agreement, adopted on December 12, 2015, at the 21st Conference of the Parties (COP21) to the United Nations Framework Convention on Climate Change (UNFCCC), stands as a landmark international treaty aimed at mitigating greenhouse gas emissions, adapting to the impacts of climate change, and mobilizing financial resources to support vulnerable nations. Signed by 196 parties and currently ratified by 195 UNFCCC member states as of early 2023, the Agreement seeks to limit the global temperature increase to well below 2°C above pre-industrial levels, with an aspirational target of 1.5°C. However, despite its ambitious goals and widespread adoption, the Paris Agreement faces significant challenges in meeting global climate targets. These challenges span legal, political, economic, and implementation dimensions, compounded by the diverse approaches countries take in incorporating international treaties into their national legal frameworks.
This article examines the multifaceted challenges hindering the Paris Agreement’s ability to achieve its climate objectives. It delves into the legal structure of the Agreement, exploring how states enter into treaties and the implications of differing legal traditions—specifically monist and dualist approaches to international law. Additionally, the article addresses the relationship between the Paris Agreement and the Vienna Convention on the Law of Treaties (VCTL) of 1969, assessing how this relationship may guide other nations in engaging with the Agreement. While the focus is on global challenges, a hypothetical country will be used to illustrate legal entry into treaties and the translation of international commitments into domestic law, acknowledging that specific constitutional provisions and practices vary widely across jurisdictions.
The Paris Agreement: Core Objectives and Legal Framework
The Paris Agreement builds on the foundation laid by the UNFCCC and the Kyoto Protocol, introducing a more flexible and inclusive framework for global climate action. Unlike its predecessors, the Paris Agreement adopts a bottom-up approach through Nationally Determined Contributions (NDCs), whereby each party sets its own emission reduction targets and reports progress periodically. The Agreement’s primary objectives, as articulated in Article 2, include:
- Holding the increase in global average temperature to well below 2°C above pre-industrial levels, and pursuing efforts to limit the increase to 1.5°C (Article 2.1(a)).
- Increasing the ability to adapt to the adverse impacts of climate change and foster climate resilience (Article 2.1(b)).
- Making finance flows consistent with a pathway towards low greenhouse gas emissions and climate-resilient development (Article 2.1(c)).
Legally, the Paris Agreement is a binding international treaty under public international law, as recognized by the United Nations. Its provisions create obligations for states to submit and update NDCs every five years (Article 4.9), transparently report on progress (Article 13), and engage in a global stocktake to assess collective progress every five years (Article 14). However, the specific targets within NDCs are not legally binding at the international level, which represents both a strength—encouraging broad participation—and a weakness, as it relies heavily on national goodwill and political commitment.
Challenges in Meeting Global Climate Targets
1. Ambiguity and Flexibility of NDCs
One of the most significant challenges facing the Paris Agreement is the non-binding nature of NDCs. While Article 4.2 mandates that each party “shall prepare, communicate and maintain successive nationally determined contributions,” it does not prescribe specific targets or enforce compliance through punitive measures. This flexibility was crucial in securing participation from major emitters like China and India, but it risks insufficient collective action. According to the UN Environment Programme’s Emissions Gap Report (2022), current NDCs, even if fully implemented, would lead to a temperature increase of 2.4–3.5°C by 2100, far exceeding the Agreement’s targets (UNEP, 2022).
Moreover, the lack of uniformity in NDC formats and timelines complicates global assessment and accountability. Some countries set absolute emission reduction targets, while others focus on intensity-based metrics or conditional pledges contingent on financial or technological support. This inconsistency undermines the Agreement’s ability to ensure equitable burden-sharing, a principle enshrined in Article 2.2, which emphasizes “common but differentiated responsibilities and respective capabilities.”
2. Implementation Gaps and National Capacity
Even where political will exists, many countries lack the institutional, financial, and technical capacity to implement their NDCs effectively. Developing nations, in particular, face significant barriers, as highlighted in Article 9 of the Paris Agreement, which commits developed countries to provide financial assistance and technology transfer. The pledge to mobilize $100 billion annually by 2020 for climate action in developing countries has not been fully met, with the OECD estimating a shortfall of $16.7 billion in 2020 (OECD, 2022). This funding gap exacerbates disparities in adaptation and mitigation efforts, undermining global progress.
Additionally, the transparency framework under Article 13, which requires biennial reporting on emissions and progress, poses challenges for countries with limited data collection and monitoring systems. Without robust reporting, the global stocktake process cannot accurately assess whether the world is on track to meet its climate goals.
3. Political Instability and Withdrawal Risks
Political shifts within key member states pose a recurring threat to the Paris Agreement’s efficacy. The United States, historically the second-largest greenhouse gas emitter, withdrew from the Agreement in 2020 under the Trump administration before rejoining in 2021 under President Biden. Reports indicate a potential second withdrawal announced in 2025, highlighting the fragility of international commitments in the face of domestic political changes (Wikipedia, 2025). Such fluctuations disrupt long-term planning and erode trust among parties, particularly when major economies fail to lead by example.
Article 28 of the Paris Agreement allows parties to withdraw after three years from the date of entry into force, with a one-year notice period. While this provision respects state sovereignty, it creates uncertainty about sustained global cooperation, especially as geopolitical tensions and economic priorities often overshadow climate commitments.
4. Economic and Social Trade-offs
Transitioning to a low-carbon economy entails significant economic and social costs, particularly for countries reliant on fossil fuel industries. The Paris Agreement acknowledges the need for a “just transition” in Article 4.15, urging parties to consider the impacts on workers and communities. However, balancing climate goals with economic stability remains a formidable challenge. For instance, coal-dependent nations like India and South Africa face resistance from domestic stakeholders when attempting to phase out fossil fuels, as such transitions threaten jobs and energy security.
Moreover, the costs of adaptation—building resilient infrastructure, relocating vulnerable populations, and protecting ecosystems—are astronomical. Small island developing states, which contribute negligibly to global emissions yet face existential threats from sea-level rise, exemplify the inequities embedded in the climate crisis. Without adequate financial and technological support, as mandated by Articles 9 and 10, these nations cannot meet their adaptation needs.
Legal Entry into Treaties: A Hypothetical Case Study
To understand the legal mechanisms through which countries engage with the Paris Agreement, this section explores how a hypothetical country—referred to as “Country X”—enters into international treaties. The process of treaty-making is governed by both international law and domestic constitutional provisions, and Country X’s approach illustrates broader challenges in aligning international commitments with national legal systems.
Under international law, the process of entering treaties is guided by the Vienna Convention on the Law of Treaties (VCTL) of 1969, specifically Articles 11–16, which outline methods of expressing consent to be bound, including signature, ratification, acceptance, or accession. For the Paris Agreement, most states expressed consent through ratification, a process involving formal approval by domestic authorities after signature at COP21 in 2015. In Country X, let us assume the constitution stipulates that international treaties must be signed by the head of state or government, as is common in many jurisdictions, and subsequently ratified by the national legislature to become binding.
Article 46 of the VCTL further clarifies that a state’s consent to a treaty is binding under international law, even if domestic procedures were not fully followed, unless the violation of internal law was manifest and concerned a rule of fundamental importance. For Country X, this means that once ratification is completed and instruments are deposited with the UN Secretary-General (as per Article 20 of the Paris Agreement), the state is legally obligated to pursue the Agreement’s objectives, regardless of internal political opposition or procedural delays.
Monist vs. Dualist Approaches to Treaties
Countries adopt either a monist or dualist approach to incorporating international treaties into national law, which significantly influences how the Paris Agreement’s provisions are implemented domestically. In a monist system, international treaties automatically become part of domestic law upon ratification, without requiring additional legislative action. In contrast, a dualist system treats international and domestic law as separate spheres, necessitating specific domestic legislation to give effect to treaty obligations.
Assuming Country X follows a dualist approach, common in countries with a British legal tradition, the Paris Agreement would not have direct effect in national courts unless translated into domestic law through an act of parliament. For instance, Country X’s legislature would need to enact climate-specific legislation to operationalize NDCs, establish carbon pricing mechanisms, or enforce emission reduction targets. This process can be delayed by political gridlock or competing national priorities, posing a challenge to timely implementation of the Agreement’s goals. If Country X were monist, as seen in some civil law traditions, ratification alone would render the Agreement enforceable domestically, potentially streamlining compliance but raising concerns about sovereignty and democratic oversight.
The dualist approach in Country X underscores a broader challenge for the Paris Agreement: the disconnect between international commitments and enforceable national policies. Even with international obligations under Article 4 to pursue domestic mitigation measures, dualist states may lag in creating the necessary legal frameworks, contributing to the global implementation gap.
The Paris Agreement and the Vienna Convention on the Law of Treaties (1969)
The Vienna Convention on the Law of Treaties (VCTL), adopted on May 23, 1969, is the cornerstone of international treaty law, codifying rules on the formation, interpretation, and termination of treaties. While the Paris Agreement itself is not a “party” to the VCTL—since only states can be parties to treaties—its legal framework operates within the norms and principles established by the VCTL. Specifically, the VCTL applies to the Paris Agreement as a treaty between states, governing aspects such as entry into force (Article 24), interpretation (Articles 31–33), and reservations (Articles 19–23).
The Paris Agreement was drafted and negotiated in accordance with VCTL rules, and its depositary, the UN Secretary-General, manages ratifications and withdrawals as per VCTL guidelines. For instance, Article 28 of the Paris Agreement on withdrawal mirrors the provisions of Article 56 of the VCTL, which addresses denunciation of treaties. This alignment ensures that the Paris Agreement adheres to widely accepted standards of international law, providing clarity and predictability for participating states.
For other countries seeking to enter into treaties like the Paris Agreement, the VCTL offers critical guidance on procedural and substantive matters. First, it emphasizes the importance of formal consent through ratification or accession (Article 14, VCTL), ensuring that states are fully aware of their obligations. Second, the VCTL’s principles of good faith (Article 26) and pacta sunt servanda (“agreements must be kept”) obligate states to honor their commitments, which is particularly relevant for the Paris Agreement given its reliance on voluntary NDCs. Third, the VCTL allows for reservations unless prohibited by the treaty (Article 19), although the Paris Agreement does not explicitly permit reservations, reflecting its aim for universal applicability.
The relationship between the Paris Agreement and the VCTL also highlights the importance of capacity-building for states with limited legal expertise in treaty-making. Developing countries, in particular, may benefit from technical assistance to navigate VCTL procedures, ensuring effective participation in global climate governance. This insight is vital as the Paris Agreement evolves through future COPs and amendments, requiring ongoing state engagement under VCTL norms.
Implications for Global Climate Governance
The legal and practical challenges facing the Paris Agreement have profound implications for global climate governance. At the international level, the lack of binding enforcement mechanisms under the Agreement necessitates alternative strategies to encourage compliance. The “naming and shaming” approach embedded in the transparency framework (Article 13) and global stocktake (Article 14) aims to leverage peer pressure and public scrutiny, but its effectiveness remains uncertain in the absence of sanctions.
Domestically, the monist-dualist divide and varying constitutional approaches to treaty incorporation underscore the need for tailored support to align national laws with international commitments. The UNFCCC and associated bodies could prioritize capacity-building initiatives, particularly for dualist states like Country X, to facilitate the translation of NDCs into enforceable policies. Moreover, strengthening financial mechanisms under Article 9 is critical to bridge the resource gap, enabling all parties to contribute to global targets equitably.
The interplay between the Paris Agreement and the VCTL also offers a blueprint for future climate treaties. By adhering to established norms of treaty law, the Agreement provides a model for balancing state sovereignty with collective action. However, the political volatility exemplified by withdrawals and funding shortfalls suggests that legal frameworks alone are insufficient. Building resilient international cooperation requires addressing underlying economic and social drivers of non-compliance, ensuring that climate action aligns with national development priorities.
Conclusion
The Paris Agreement represents a historic milestone in the fight against climate change, uniting nearly all nations under a shared commitment to limit global warming. However, challenges in meeting its ambitious targets—ranging from the flexibility of NDCs to implementation gaps, political instability, and economic trade-offs—threaten to undermine its effectiveness. Legally, the Agreement operates within the framework of international treaty law as codified by the VCTL, providing a structured process for state engagement while highlighting the complexities of translating international obligations into national action, particularly in dualist systems.
Using the hypothetical case of Country X, this article has illustrated how constitutional provisions and legal traditions shape a state’s ability to enter and implement treaties like the Paris Agreement. For global climate governance to succeed, these legal nuances must be addressed alongside political and economic barriers. The Paris Agreement’s alignment with VCTL principles offers valuable lessons for other countries and future treaties, emphasizing the importance of formal consent, good faith, and capacity-building in fostering international cooperation.
As the world approaches critical deadlines for emission reductions, the Paris Agreement stands at a crossroads. Strengthening its mechanisms—through enhanced funding, standardized reporting, and robust domestic legal integration—will be essential to bridge the gap between aspiration and achievement. Only through sustained, collective effort can the global community hope to avert the catastrophic consequences of unchecked climate change.
References
- OECD (2022). Climate Finance Provided and Mobilised by Developed Countries in 2016-2020. Organisation for Economic Co-operation and Development.
- UNEP (2022). Emissions Gap Report 2022: The Closing Window. United Nations Environment Programme.
- United Nations (1969). Vienna Convention on the Law of Treaties. Treaty Series, vol. 1155, p. 331.
- United Nations (2015). Paris Agreement. Adopted at the 21st Conference of the Parties to the UNFCCC. Available at: https://unfccc.int/process-and-meetings/the-paris-agreement.
- Wikipedia (2025). Paris Agreement. Retrieved from https://en.wikipedia.org/wiki/Paris_Agreement.
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