Introduction
The Paris Agreement, adopted in 2015 under the United Nations Framework Convention on Climate Change (UNFCCC), represents a landmark international treaty aimed at combating climate change by limiting global temperature rise to well below 2°C above pre-industrial levels, while pursuing efforts to limit the increase to 1.5°C. Signed by 196 parties during the 21st Conference of the Parties (COP21) in Paris, France, the Agreement is a pivotal instrument in global climate governance, focusing on mitigation, adaptation, and financial support for climate-resilient development. However, achieving the ambitious global carbon emission goals set by the Agreement faces numerous challenges, including varying national commitments, legal frameworks for treaty implementation, economic disparities, and geopolitical dynamics. This article examines these challenges in detail, explores the legal mechanisms for entering into treaties under the Paris Agreement, and discusses the relationship between the Agreement and the Vienna Convention on the Law of Treaties (VCTL) of 1969. Additionally, it addresses the monist or dualist approaches to treaty incorporation into national law, providing a theoretical framework for understanding how countries translate international commitments into domestic policy.
The Paris Agreement and Global Carbon Emission Goals
The Paris Agreement establishes a framework for countries to submit Nationally Determined Contributions (NDCs), which are voluntary commitments outlining each nation’s efforts to reduce greenhouse gas emissions and adapt to climate change impacts. Unlike its predecessor, the Kyoto Protocol, the Paris Agreement adopts a bottom-up approach, allowing flexibility for countries to set their own targets based on national circumstances. However, this flexibility poses a significant challenge in ensuring collective action sufficient to meet global emission reduction targets. As outlined in Article 2 of the Paris Agreement, the overarching goal is to hold the increase in global average temperature to well below 2°C and pursue efforts to limit it to 1.5°C (UNFCCC, 2015). Achieving this requires a drastic reduction in global carbon emissions, with the Intergovernmental Panel on Climate Change (IPCC) estimating a need for net-zero CO2 emissions by 2050 to meet the 1.5°C target (IPCC, 2018).
One of the primary challenges is the disparity in ambition among NDCs. While some countries, such as those in the European Union, have set aggressive targets aligned with net-zero by mid-century, others, particularly developing nations, face constraints due to economic priorities and limited resources. The Agreement acknowledges these disparities through the principle of “common but differentiated responsibilities and respective capabilities” (CBDR-RC) as stated in Article 2.2 (UNFCCC, 2015). However, this principle, while equitable in intent, often results in insufficient aggregate reductions, as major emitters may prioritize short-term economic gains over long-term climate goals. Furthermore, the lack of legally binding enforcement mechanisms for NDCs under the Paris Agreement means that compliance largely depends on political will and international pressure, rather than legal accountability.
Another challenge lies in the monitoring and transparency framework established under Article 13 of the Agreement, which requires parties to report on their progress in implementing NDCs (UNFCCC, 2015). While this framework aims to foster accountability, inconsistencies in data reporting, varying methodologies, and limited technical capacity in some nations undermine the effectiveness of global tracking. These issues are compounded by the withdrawal and re-entry dynamics of key emitters, such as the United States, which withdrew from the Agreement in 2020, rejoined in 2021, and announced another potential withdrawal in 2025, highlighting the fragility of international commitment (Wikipedia, 2025).
Financial and technological barriers further exacerbate the challenges. Article 9 of the Paris Agreement mandates developed countries to provide financial assistance to developing nations, with a goal of mobilizing $100 billion annually by 2020 (UNFCCC, 2015). However, funding has consistently fallen short, hindering the capacity of vulnerable nations to transition to low-carbon economies and build resilience against climate impacts (Council on Foreign Relations, 2025). Without robust financial mechanisms and technology transfer, the global effort to reduce emissions remains fragmented and unequal.
Legal Framework for Entering into Treaties under the Paris Agreement
The Paris Agreement, as an international treaty, operates within the broader framework of international law, which governs how states enter into, ratify, and implement treaties. The legal basis for a country to enter into treaties, including the Paris Agreement, typically depends on its national constitution and legal system. Since the query refers to “this country” without specifying a particular nation, this section will provide a generalized framework while emphasizing that specific constitutional provisions vary by state. For illustrative purposes, references to the legal text of the Paris Agreement will be used to explain the treaty’s provisions on entry and implementation.
Under international law, the process of entering into a treaty generally involves negotiation, signature, and ratification. Article 24 of the Paris Agreement specifies the conditions for entry into force, stating that the Agreement shall enter into force on the 30th day after the date on which at least 55 Parties to the UNFCCC, accounting for at least 55% of total global greenhouse gas emissions, have deposited their instruments of ratification, acceptance, approval, or accession (UNFCCC, 2015). This dual threshold ensures that both a significant number of countries and major emitters are committed before the treaty becomes operational. For an individual country to join, it must follow its domestic legal procedures for treaty ratification, which are typically outlined in its constitution or relevant legislation.
In a hypothetical context, if a country’s constitution vests treaty-making power in the executive branch (e.g., the President or Prime Minister), the head of state or government may sign the treaty as an expression of intent to be bound. However, ratification often requires legislative approval, particularly in democratic systems, to ensure that the treaty aligns with national interests and legal norms. For instance, under the Paris Agreement, signature alone does not create binding obligations; it is the act of ratification, as per Article 21, that legally commits a state to the treaty’s terms (UNFCCC, 2015). After ratification, the country deposits its instrument of ratification with the UN Secretary-General, who serves as the depository under Article 25 (UNFCCC, 2015).
The legal process for treaty entry also intersects with a country’s approach to international law, specifically whether it adopts a monist or dualist perspective. These concepts will be explored in greater detail in the next section to clarify how treaties like the Paris Agreement are incorporated into national law.
Monist vs. Dualist Approach to Treaties and National Incorporation
The incorporation of international treaties into domestic law varies significantly depending on whether a country follows a monist or dualist legal tradition. In a monist system, international law and domestic law are considered part of a single legal order. Once a treaty is ratified, it automatically becomes part of national law and can be directly enforced by domestic courts without the need for additional legislation. In contrast, a dualist system views international law and domestic law as separate legal orders. In such systems, a ratified treaty does not automatically have domestic effect; it must be transformed into national law through implementing legislation passed by the legislature.
Since the query refers to “this country” without specification, it is not possible to definitively state whether it follows a monist or dualist approach. However, a generalized analysis can illustrate the implications for the Paris Agreement. For example, in a monist system, once a country ratifies the Paris Agreement, its provisions—such as the commitment to submit NDCs under Article 4—could theoretically be invoked in domestic courts as binding law, provided that the provisions are self-executing (i.e., sufficiently precise to be directly applicable without further clarification) (UNFCCC, 2015). However, many provisions of the Paris Agreement, including NDCs, are framed as obligations of conduct rather than result, meaning they require further domestic action to be operationalized, even in monist systems.
In a dualist system, ratification of the Paris Agreement would not automatically translate into enforceable domestic law. Instead, the government would need to enact specific legislation to translate commitments—such as emission reduction targets or adaptation policies—into binding national regulations. For instance, a country might pass a climate law to establish a carbon pricing system or renewable energy targets to align with its NDC. Failure to enact such legislation could result in a gap between international commitments and domestic enforcement, undermining the effectiveness of the Paris Agreement at the national level.
Most countries operate with a hybrid or context-dependent approach, blending elements of monism and dualism depending on the nature of the treaty and domestic legal traditions. For the Paris Agreement specifically, even in monist systems, the non-binding nature of NDCs (as per Article 4.2, which states that each Party “shall prepare, communicate and maintain” NDCs but does not mandate specific outcomes) often necessitates additional domestic legislation to ensure compliance (UNFCCC, 2015). This dynamic highlights a broader challenge: regardless of monist or dualist orientation, effective implementation of the Paris Agreement requires robust national legal and policy frameworks, which many countries struggle to establish due to political, economic, or institutional barriers.
The Paris Agreement and the Vienna Convention on the Law of Treaties (VCTL) 1969
The Vienna Convention on the Law of Treaties (VCTL) of 1969 is a foundational instrument in international law, codifying the rules and principles governing the formation, interpretation, application, and termination of treaties. It provides the legal framework within which treaties like the Paris Agreement are negotiated and implemented. Although the Paris Agreement does not explicitly reference the VCTL, it operates within the customary international law principles that the VCTL codifies, many of which are binding on all states as customary norms, even for non-parties to the VCTL.
The Paris Agreement itself is a treaty under the definition provided in Article 2(1)(a) of the VCTL, which defines a treaty as “an international agreement concluded between States in written form and governed by international law” (UN, 1969). As such, the processes of signature, ratification, and entry into force outlined in the Paris Agreement (Articles 20 to 24) align with the procedural norms of the VCTL, particularly Articles 11 to 16, which address means of expressing consent to be bound by a treaty (UNFCCC, 2015; UN, 1969). Furthermore, the interpretation of the Paris Agreement’s provisions would be guided by VCTL principles, such as Article 31, which emphasizes interpreting treaties in good faith based on the ordinary meaning of terms in their context and in light of the treaty’s object and purpose (UN, 1969).
Regarding whether the Paris Agreement is a “party” to the VCTL, it is important to clarify that treaties themselves are not parties to other treaties; rather, states are parties to treaties. The VCTL applies to the Paris Agreement as a legal instrument, and states that are parties to both the VCTL and the Paris Agreement are bound by the VCTL’s rules in their implementation of the latter. As of 2025, the majority of states that are parties to the Paris Agreement are also parties to the VCTL or recognize its provisions as customary international law, ensuring broad alignment in treaty practice (UN Treaty Collection, 2025).
For other countries considering entering into treaties like the Paris Agreement, the relationship with the VCTL provides critical guidance. First, it underscores the importance of formal ratification processes to express consent to be bound, as outlined in VCTL Article 14 (UN, 1969). Second, it highlights the need for clarity in treaty language to avoid ambiguity in obligations, a lesson relevant to the Paris Agreement’s flexible NDC framework. Third, the VCTL’s provisions on treaty reservations (Articles 19-23) inform how states might limit their commitments under the Paris Agreement, although the latter does not allow reservations as per Article 27 (UNFCCC, 2015; UN, 1969). Countries can draw on these principles to ensure that their participation in climate treaties is legally sound and aligned with international norms, thereby fostering trust and cooperation in global climate governance.
Broader Challenges in Achieving Carbon Emission Goals
Beyond legal frameworks, the Paris Agreement faces systemic challenges in achieving global carbon emission goals. One significant barrier is the economic reliance on fossil fuels, particularly in major emitting countries. Transitioning to renewable energy requires substantial investment in infrastructure, technology, and workforce retraining, which can be economically disruptive in the short term. Developing countries, in particular, argue for greater financial and technological support, as their historical contribution to emissions is minimal compared to industrialized nations. Article 6 of the Paris Agreement attempts to address this through mechanisms like carbon markets and cooperative approaches, but implementation remains inconsistent (UNFCCC, 2015).
Geopolitical tensions also hinder progress. Climate policies are often subordinate to national security or economic competition, as seen in trade disputes over green technologies or resistance to energy transitions that affect domestic industries. The periodic withdrawal of key players from the Agreement, as with the United States, underscores the fragility of international consensus. Moreover, the rise of populism and climate skepticism in various regions challenges the political will needed for sustained action (Council on Foreign Relations, 2025).
Finally, the urgency of the climate crisis itself poses a challenge. The IPCC warns that global emissions must peak before 2025 and decline by about 43% by 2030 to meet the 1.5°C target (IPCC, 2022). Yet, current NDCs, even if fully implemented, are projected to result in warming of 2.4–3.5°C by 2100, according to UNEP’s Emissions Gap Report (UNEP, 2023). This gap between ambition and action illustrates the structural limitations of a voluntary framework like the Paris Agreement, where enforcement relies on moral suasion rather than legal compulsion.
Policy Recommendations and Future Directions
To overcome these challenges, several policy measures can be proposed. First, strengthening the transparency framework under Article 13 of the Paris Agreement is critical. Standardized reporting guidelines and enhanced capacity-building for developing countries can improve the accuracy and comparability of emission data (UNFCCC, 2015). Second, developed nations must fulfill and exceed their financial commitments under Article 9, ensuring that the $100 billion annual target is met and scaled up post-2025 to address loss and damage, as agreed at COP27 (UNFCCC, 2022).
Third, integrating climate goals into broader economic policies can align national interests with global objectives. Carbon pricing, subsidies for renewable energy, and green industrial policies can incentivize low-carbon transitions while minimizing economic disruption. Fourth, leveraging international institutions like the UNFCCC to mediate disputes and foster dialogue can mitigate geopolitical barriers, ensuring that climate action is not derailed by unrelated tensions.
Finally, from a legal perspective, countries should prioritize domesticating the Paris Agreement through comprehensive climate legislation, whether through monist direct application or dualist transformation. Such laws should establish clear timelines, accountable institutions, and enforceable penalties to bridge the gap between international commitments and national action.
Conclusion
The Paris Agreement stands as a historic accord in the fight against climate change, uniting nations under a common goal of limiting global temperature rise and reducing carbon emissions. However, its success is constrained by a range of challenges, from the voluntary nature of NDCs to disparities in economic capacity, geopolitical instability, and the urgency of the climate crisis itself. Legally, the Agreement operates within the framework of international law, including principles codified in the VCTL of 1969, and its implementation at the national level depends on whether a state follows a monist or dualist approach to treaty incorporation. For countries seeking to engage with the Paris Agreement, adherence to international legal norms and the development of robust domestic frameworks are essential to translate commitments into meaningful action. While the road to achieving global carbon emission goals remains fraught with obstacles, targeted policy interventions, enhanced financial support, and sustained international cooperation offer a pathway to bridge the ambition gap and safeguard the planet for future generations.
References
- Council on Foreign Relations. (2025). Global Climate Agreements: Successes and Failures. Available at: https://www.cfr.org/backgrounder/paris-global-climate-change-agreements
- IPCC. (2018). Global Warming of 1.5°C. Intergovernmental Panel on Climate Change.
- IPCC. (2022). Climate Change 2022: Mitigation of Climate Change. Intergovernmental Panel on Climate Change.
- UN. (1969). Vienna Convention on the Law of Treaties. United Nations Treaty Series, Vol. 1155, p. 331.
- UNEP. (2023). Emissions Gap Report 2023. United Nations Environment Programme.
- UNFCCC. (2015). Paris Agreement. United Nations Framework Convention on Climate Change.
- UNFCCC. (2022). COP27 Outcomes: Loss and Damage Fund. United Nations Framework Convention on Climate Change.
- UN Treaty Collection. (2025). Status of Treaties: Vienna Convention on the Law of Treaties. United Nations.
- Wikipedia. (2025). Paris Agreement. Available at: https://en.wikipedia.org/wiki/Paris_Agreement
