Introduction
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), represents a historic milestone in global efforts to combat climate change. Signed by 196 parties and ratified by 195 members of the UNFCCC as of early 2023, the treaty aims to limit global temperature rise to well below 2°C above pre-industrial levels, with an aspirational target of 1.5°C. Beyond mitigation, the Agreement also addresses adaptation to climate impacts and provides a framework for financial and technical support to vulnerable nations. Despite its ambitious goals, the Paris Agreement faces significant challenges in meeting global climate targets, ranging from inadequate national commitments to enforcement issues, economic disparities, and legal complexities surrounding treaty implementation. This article examines these challenges in detail, focusing on the legal mechanisms for treaty adoption, the role of monist and dualist approaches in national incorporation of international law, and the relationship between the Paris Agreement and the Vienna Convention on the Law of Treaties (VCTL) of 1969. Additionally, it explores how a hypothetical country—referred to as “this country” for the purposes of this analysis—engages with international treaties like the Paris Agreement under its legal framework.
The Paris Agreement: Objectives and Mechanisms
The Paris Agreement establishes a framework for global climate action through a combination of binding and voluntary commitments. Its core objective, as articulated in Article 2, is to strengthen the global response to climate change by maintaining temperature increases within safe limits, enhancing adaptive capacity, and fostering climate resilience while ensuring financial flows are consistent with low-emission and climate-resilient development pathways. Unlike its predecessor, the Kyoto Protocol, which imposed mandatory emission reduction targets on developed countries, the Paris Agreement relies on Nationally Determined Contributions (NDCs). Under Article 4, each party is required to prepare, communicate, and maintain successive NDCs that reflect their highest possible ambition, with a review mechanism every five years to encourage progressive strengthening of targets.
Other key mechanisms include the transparency framework under Article 13, which mandates regular reporting on emissions and progress toward NDCs, and the global stocktake outlined in Article 14, a periodic assessment to evaluate collective progress toward long-term goals. Additionally, Articles 9, 10, and 11 address financial support, technology transfer, and capacity building, particularly for developing countries. While these provisions create a robust structure for international cooperation, the Agreement’s success hinges on the willingness and capacity of individual states to translate commitments into actionable policies.
Challenges in Meeting Global Climate Targets
Inadequacy of Nationally Determined Contributions (NDCs)
One of the primary challenges facing the Paris Agreement is the inadequacy of current NDCs in meeting the 1.5°C or even the 2°C target. According to the UN Environment Programme’s Emissions Gap Report (2022), the aggregate impact of existing NDCs, even if fully implemented, would lead to a temperature increase of approximately 2.4–3.5°C by the end of the century. This discrepancy arises from several factors, including insufficient ambition in initial commitments, lack of specificity in policy measures, and the voluntary nature of NDCs, which are not legally binding under international law. For many countries, economic reliance on fossil fuels and competing developmental priorities hinder the adoption of more aggressive targets. Furthermore, the five-year review cycle, while intended to encourage progressive ambition, lacks a mechanism to penalize non-compliance, allowing some nations to delay meaningful action.
Enforcement and Accountability Issues
The Paris Agreement’s reliance on a bottom-up approach, where countries self-determine their contributions, contrasts with a top-down enforcement model. While Article 15 establishes a compliance committee to facilitate implementation, this body is non-punitive and focuses on support rather than sanction. The absence of a robust enforcement mechanism raises questions about accountability, particularly for major emitters who fail to meet their targets. Historical examples, such as the United States’ withdrawal from the Agreement in 2020 (reversed in 2021 and threatened again in 2025), illustrate the fragility of political commitment to climate goals. Such fluctuations undermine global trust and collective momentum, as other nations may perceive reduced obligations when key players disengage.
Economic and Social Disparities
Economic disparities between developed and developing nations pose another significant barrier. Under Article 9, developed countries are obligated to provide financial assistance—targeting $100 billion annually by 2020—to support mitigation and adaptation efforts in less affluent states. However, funding has consistently fallen short, with the OECD reporting that only $83.3 billion was mobilized in 2020. Developing countries, often the most vulnerable to climate impacts, argue that insufficient support hampers their ability to transition to low-carbon economies. Additionally, the social cost of climate policies, such as carbon taxes or fossil fuel phase-outs, can exacerbate inequality within nations, leading to public resistance and political backlash, as seen in the “Yellow Vest” protests in France over fuel tax hikes in 2018.
Technological and Infrastructural Barriers
Meeting the Paris Agreement’s targets requires rapid deployment of clean energy technologies and large-scale infrastructural transformation. Yet, many countries lack access to affordable renewable energy solutions or the technical expertise to implement them. Article 10 of the Agreement promotes technology transfer, but intellectual property rights and commercial interests often limit the diffusion of critical innovations. Furthermore, aging infrastructure in industrialized nations and the absence of basic systems in developing ones complicate the transition to sustainable models. For instance, coal-dependent economies like India and China face significant hurdles in phasing out fossil fuels without jeopardizing energy security or economic stability.
Legal Framework for Treaty Adoption: The Case of “This Country”
To understand the challenges of implementing the Paris Agreement at the national level, it is instructive to examine how a specific country—referred to here as “this country”—engages with international treaties under its legal framework. The process by which a state enters into treaties is governed by both international law, primarily the Vienna Convention on the Law of Treaties (VCTL) of 1969, and domestic constitutional provisions. The Paris Agreement itself does not prescribe specific procedures for ratification or implementation, leaving these matters to national discretion as per Article 20, which outlines the processes for signature, ratification, acceptance, approval, or accession, and Article 21, which specifies entry into force upon ratification by at least 55 parties accounting for 55% of global greenhouse gas emissions.
In “this country,” the legal authority to enter into international treaties typically resides with the executive branch, often requiring parliamentary approval or legislative ratification, depending on the nature of the treaty. Assuming a hypothetical constitutional framework, let us consider that “this country” vests treaty-making power in the head of state or government, as stipulated in a provision akin to Article II, Section 2 of the U.S. Constitution (for comparative purposes), which grants the President the power to make treaties with the advice and consent of the Senate. Under such a system, the executive would negotiate and sign the Paris Agreement, followed by submission to the legislature for approval before formal ratification. This ensures that international commitments align with domestic priorities and legal norms, providing a check against unilateral executive action.
Monist vs. Dualist Approach in “This Country”
The incorporation of international treaties like the Paris Agreement into national law depends on whether “this country” follows a monist or dualist approach to international law. In a monist system, international law is automatically part of domestic law upon ratification, requiring no additional legislative action for enforcement. Conversely, in a dualist system, treaties must be transformed into national law through specific legislation before they become enforceable domestically. For the purposes of this analysis, let us assume that “this country” adheres to a dualist approach, a common framework in many jurisdictions, including the United Kingdom. Under this system, the Paris Agreement, once ratified, does not automatically confer rights or obligations within the national legal order. Instead, the legislature must enact enabling statutes to translate commitments—such as emission reduction targets under Article 4—into binding domestic policies.
This dualist approach can create delays or inconsistencies in implementing the Paris Agreement, as legislative processes are subject to political dynamics and competing priorities. For instance, if the ruling party lacks a parliamentary majority or faces opposition from fossil fuel-dependent constituencies, the passage of climate legislation may be stalled. Moreover, even after domestication, national laws may interpret or prioritize treaty obligations differently, leading to discrepancies between international commitments and local action. This highlights a critical challenge in aligning global climate targets with national legal frameworks, particularly in dualist states where international law lacks direct effect.
The Paris Agreement and the Vienna Convention on the Law of Treaties (1969)
The Vienna Convention on the Law of Treaties (VCTL), adopted in 1969, serves as the foundational framework for the creation, interpretation, and application of international treaties. It codifies customary international law on treaties, providing rules for their formation, amendment, termination, and enforcement. A key question is whether the Paris Agreement operates within the ambit of the VCTL and how this relationship informs state practice in entering treaties.
The Paris Agreement, as an international treaty under the UNFCCC, falls within the scope of the VCTL’s definition of a treaty under Article 2(1)(a), which describes a treaty as “an international agreement concluded between States in written form and governed by international law.” While the VCTL does not apply retroactively to treaties concluded before its entry into force in 1980, it governs subsequent agreements like the Paris Agreement, which was adopted in 2015. Most provisions of the VCTL, such as those on treaty interpretation (Articles 31–33) and the obligation to perform treaties in good faith (Article 26, the principle of pacta sunt servanda), are considered customary international law and thus bind even non-parties to the Convention. Therefore, the Paris Agreement is subject to the VCTL’s principles, whether or not all signatories are parties to the VCTL itself.
For other countries, the interplay between the Paris Agreement and the VCTL underscores the importance of adhering to established norms in treaty-making. The VCTL provides procedural clarity on issues such as ratification (Article 14), reservations (Articles 19–23), and entry into force (Article 24), which can guide states in formalizing their commitments under the Paris Agreement. For instance, countries must ensure that their ratification processes align with both domestic constitutional requirements and international legal standards to avoid disputes over validity or compliance. Additionally, the VCTL’s emphasis on good faith implementation serves as a reminder that mere ratification of the Paris Agreement is insufficient; states must actively pursue their NDCs and other obligations to uphold the treaty’s objectives.
The relevance of the VCTL also extends to potential conflicts or ambiguities within the Paris Agreement. For example, disputes over the interpretation of terms like “highest possible ambition” in Article 4 of the Agreement can be resolved using the VCTL’s interpretive guidelines, which prioritize the ordinary meaning of text in light of its object and purpose. This framework is particularly instructive for countries with limited experience in international climate law, offering a structured approach to engaging with complex multilateral agreements.
Implications for Global Climate Governance
The challenges facing the Paris Agreement are emblematic of broader issues in global climate governance. The reliance on voluntary commitments reflects a pragmatic approach to securing universal participation but sacrifices enforceability. Strengthening the Agreement could involve introducing mechanisms for graduated sanctions or incentives tied to compliance, though such measures risk alienating key stakeholders. Alternatively, enhancing financial and technological support under Articles 9 and 10 could address capacity gaps, enabling more equitable burden-sharing. However, mobilizing resources at the necessary scale remains a political and logistical challenge, particularly given competing global crises such as economic downturns and geopolitical conflicts.
From a legal perspective, the diversity of national approaches to treaty incorporation—monist versus dualist—complicates the harmonization of climate policies. States with dualist systems, like “this country” in our hypothetical analysis, must prioritize legislative action to ensure that international commitments translate into enforceable domestic measures. This underscores the need for capacity building in legal and institutional frameworks, particularly in developing countries where governance structures may be less equipped to handle complex climate legislation.
The relationship between the Paris Agreement and the VCTL also highlights the importance of international legal norms in sustaining multilateral cooperation. By adhering to VCTL principles, states can build trust and predictability in their treaty engagements, fostering a more cohesive global response to climate change. For countries hesitant to join or fully implement the Paris Agreement, the VCTL offers a neutral and widely accepted blueprint for navigating international obligations, potentially reducing barriers to participation.
Conclusion
The Paris Agreement represents a pivotal effort to address the existential threat of climate change, uniting nations under a shared commitment to limit global warming and adapt to its impacts. However, significant challenges—ranging from inadequate NDCs and enforcement gaps to economic disparities and legal complexities—threaten its ability to achieve the ambitious targets of 1.5°C or 2°C. The case of “this country” illustrates how national legal frameworks, particularly dualist systems, can create friction in translating international commitments into actionable policies. Meanwhile, the Paris Agreement’s alignment with the Vienna Convention on the Law of Treaties reinforces the importance of established norms in guiding state behavior, offering a model for other nations to engage with multilateral climate efforts. Ultimately, overcoming these challenges will require not only enhanced ambition and resources but also a renewed emphasis on legal and institutional coherence at both national and international levels. Only through such concerted action can the Paris Agreement fulfill its promise of a sustainable, low-carbon future.
References
- Paris Agreement. (2015). Adopted at the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change, Paris, France. Available at: https://unfccc.int/process-and-meetings/the-paris-agreement
- United Nations Environment Programme (UNEP). (2022). Emissions Gap Report 2022: The Closing Window. Nairobi: UNEP.
- Vienna Convention on the Law of Treaties (VCTL). (1969). United Nations, Treaty Series, vol. 1155, p. 331. Available at: https://legal.un.org/ilc/texts/instruments/english/conventions/1_1_1969.pdf
- Organisation for Economic Co-operation and Development (OECD). (2022). Climate Finance Provided and Mobilised by Developed Countries in 2016-2020. Paris: OECD Publishing.
- Council on Foreign Relations. (2025). Global Climate Agreements: Successes and Failures. Available at: https://www.cfr.org/backgrounder/paris-global-climate-change-agreements
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