Reassessing Common But Differentiated Responsibilities and Respective Capabilities

The Principle of ‘Common But Differentiated Responsibilities and Respective Capabilities’ (CBDR-RC) holds all states responsible for addressing human-driven climate change and environmental destruction but acknowledges that some states have historically contributed more to the climate crisis and are in a better economic position to take action as a consequence of the long-standing continuity of global economic inequity. Emerging first in Principle 7 of the 1992 Rio Declaration, it was incorporated into Art. 3.1 of the United Framework Convention on Climate Change (UNFCCC), making the principle of CBDR-RC a cornerstone of the international climate change legal regime.

The Paris Agreement explicitly references CBDR-RC in Article 2, providing that the Agreement “will be implemented to reflect equity and the principle of common but differentiated responsibilities and respective capabilities, in the light of different national circumstances.” Thus, the principle of CBDR-RC applies not only to the states’ pledges on climate change mitigation and adaptation but also to their commitment to financing climate change efforts.

This piece (a) discusses how the principle of CBDR-RC currently operates under the Paris Agreement; (b) analyzes the potential contentions caused by application of the Principle at COP 29; and (c) turns to international tribunal decisions that provide clarifying insight that might shape the practical implications of the principle of CBDR-RC in international climate action moving forward. It concludes that the application of CBDR-RC in the Paris Agreement should evolve with the changing economic and geopolitical realities. A shift away from the hardline differentiation between developed and developing countries would allow countries with emerging economies to contribute more as their economies grow and recognize that development and climate action should go together.

Nationally Determined Contributions

The principle of CBDR-RC is incorporated into the Paris Agreement Parties’ nationally determined contributions (NDCs). These are the pledges that all Parties are required under Article 4(2) of the Paris Agreement to submit on how they plan to reduce greenhouse gas (GHG) emissions, in line with the goal of limiting the global temperature increase to well below 2°C, and ideally below 1.5°C. While the Agreement requires Parties to submit NDCs on a five-year cycle—thereby fulfilling the “common” element in CBDR-RC—it does not prescribe numerical or sectoral targets. This allows Parties to account for their own responsibility in addressing climate change according to their perceived capability to implement mitigation and adaptation measures as well as contribute to climate finance.

Under Art. 4.4 of the Agreement, developed countries are expected to “take the lead” and proffer more ambitious NDCs than developing countries. When the window to submit new NDCs opens at the 29th Conference of the Parties (COP 29) to the UNFCCC, Parties will continue facing pressure to increase the ambition of their proposed contributions. The next round of NDCs, which should be informed by the language of the Global Stocktake calling for increased ambition, are due in 2025.

Global Stocktake

At COP 28 in 2023, Parties to the Agreement agreed upon the first Global Stocktake (GST), an analysis of progress towards achieving the Paris goals conducted every five years. The GST then proffers new pathways towards meeting those goals and increasing ambition in states’ NDCs. The outcome of the GST reaffirms that states’ NDCs should reflect the “highest possible ambition” keeping in mind the principle of CBDR-RC in light of the national circumstances. The text references the principle of CBDR-RC on four occasions, with one such reference in the second paragraph of the text, reflecting the weight parties continue to give to the principle.

However, the first GST also revealed a distinctive weakness in the Agreement’s application of the principle of CBDR-RC:  Allowing countries to determine their pledges according to their perceived responsibility and capability has resulted in NDCs that are not on track to meet the goals of the Agreement within the timelines necessary to avoid some irreversible impacts of climate change. Further, it also opened the discussion for the use of “transitional fuels”, in lieu of adopting the ambitious goal of phasing out fossil fuels altogether, to give more time for economies that rely on fossil fuel production, causing concern among climate experts.

The solution to remedy this weakness in the application of CBDR-RC is already in the Agreement’s architecture. Art. 4.19 encourages Parties “to formulate and communicate long-term low greenhouse gas emission development strategies”, while upholding the principle of CBDR-RC. Parties with fossil fuel-reliant economies could be supported in including fossil fuel phase-out in their NDCs or in a separate Long-Term Low Emission Development Strategies (LT-LEDS). Art. 7.7(b) encourages Parties to strengthen existing institutional arrangements under the UNFCCC that provide technical support to countries. Providing technical support and capacity-building to economies reliant on fossil fuel production could alleviate the need for adopting transitional fuels.

States can set goals in their NDCs that are more ambitious than what the GST requires, making the upcoming COP 29 negotiations an important period for stakeholders to push states towards the highest possible ambition regardless of the base requirements the GST calls for.

The Principle of CBDR-RC and Loss and Damage

The principle of CBDR-RC also plays a role in identifying Parties that should contribute support and assistance to addressing loss and damage. In the last two COPs, Parties agreed to establish new funding arrangements to assist developing countries particularly vulnerable to climate change in addressing loss and damage and to operationalize a Fund for responding to Loss and Damage, the details of which will be discussed in greater detail in another blog post forming part of this symposium. (‘FRLD’ or ‘the Fund’)

Neither the text of the Paris Agreement nor the subsequent decisions (decision 1/CP.28, decision 5/CMA.5, decision 1/CP.27, decision 2/CMA.4) identify who should contribute to the fund. Loss and damage—as originally construed in submissions of the Alliance of Small Island States in the drafting of the UNFCCC—was a form of insurance in favor of vulnerable small island developing states for the detrimental impacts of sea level rise. Subsequent discussions would expand the scope of compensation and identify industrialized countries as the source for such compensation, owing to their historical GHG emissions.

To this day, Parties to the UNFCCC and especially to the Paris Agreement within that framework agreement have not resolved the debate on compensation, choosing instead to sidestep those discussions in the interest of operationalizing a support mechanism. As the Loss and Damage Fund begins to fulfill its mandate of mobilizing financial assistance, discussions on contributors are likely to arise again.

CBDR-RC could inform the determination and expand the list of contributors to the Fund. The Sixth Assessment Report of the Intergovernmental Panel on Climate Change (‘IPCC’) has shown that other developing countries, with relatively greater economic capacity, like China, Saudi Arabia, the United Arab Emirates, and Russia,  are also now major contributors to climate change. This shift in GHG emissions is likely to create tensions among developing countries as implementation and capitalization of the Fund progresses.

It is important to note that the Fund is considered a major achievement of the Egypt and UAE COP Presidencies in 2022 and 2023, respectively. In their October 2024, BRICS members­—which now includes Egypt and the UAE, along with Malaysia, Indonesia, Vietnam, Thailand, and other developing countries, among the initial grouping of Brazil, Russia, India, China, and South Africa—expressed their commitment to a successful outcome at COP 29, “with an expectation of strong outcomes on climate finance to developing countries, as a critical enabler for delivering on the current and future … ambitions in mitigation, adaptation and loss and damage.”

CBDR-RC in Climate Finance Discussions at COP 29

With the deadline for establishing the New Collective Quantified Goal on Climate Finance (NCQG) fast approaching and the operationalization of the Loss and Damage Fund completed in the previous COP, CBDR-RC will likely underpin climate finance discussions at COP 29 in Azerbaijan.

“[I]n continuation of their existing obligations under the [UNFCCC]”, the Paris Agreement requires developed country Parties to continue providing financial resources to assist developing country Parties. This phrasing has created much debate among developed countries and emerging economies. The UNFCCC and its Kyoto Protocol—predecessor to the Paris Agreement—create a hardline dichotomy between developed and developing countries: industrialized countries are listed in Annex I and are subject to quantified emission reduction commitments (QERC) and other mandatory obligations. Developing countries (non-Annex I) are bound by the goals of the UNFCCC but are not required to abide by QERCs.

The Paris Agreement does not explicitly maintain the Annex I/non-Annex I dichotomy, generating the debate on whether this deviation allows for more flexibility in classifying which nations are most responsible for contributing to the Paris goals.

Adherence to the Annex I/non-Annex I dichotomy could prove to be the main hurdle in leaving COP 29 with an agreed-upon NCQG. The European Union (EU), supported by other developed countries, has expressed the desire to see additional contributions to those of developed country Parties from the largest polluting countries with capacity to provide climate finance. Emerging markets, like China and Saudi Arabia, oppose this notion, maintaining that only developed countries should shoulder the responsibility of contributing to the new goal.

If Parties are unable to make concessions regarding which states should contribute, negotiations on NCQG could extend past this year’s COP. At COP 28, delegates deferred a record number of agenda items to this year’s COP, with finance mechanisms causing the most contention. Rapid deployment of climate finance mechanisms is necessary to keep the Paris Goals within reach; further delay from COP 29 and increasing tension could be detrimental to effective international climate action.

CBDR-RC in International Tribunals: Guidance from IACtHR, ICJ, and ITLOS Advisory Opinions

As emerging economies become major global emitters, the traditional classification of “developed” and “developing” countries in international climate law is increasingly seen as inadequate. This dichotomy no longer reflects current global emissions and economic power, causing international courts and tribunals to attempt to clarify obligations against the background of CBDR-RC.

In its 2024 Advisory Opinion, the International Tribunal for the Law of the Sea (ITLOS) reaffirmed the principle of CBDR-RC under the UN Convention on the Law of the Sea (UNCLOS), emphasizing the heavier burden on developed countries. However, ITLOS upheld the traditional categorization of developed and developing countries, maintaining flexibility within the existing framework without introducing new distinctions.

In contrast, the upcoming advisory opinions from the Inter-American Court of Human Rights (IACtHR) and the International Court of Justice (ICJ) have the potential to shift how climate responsibilities are understood more significantly.

The IACtHR, focusing on the human rights implications of climate change, will address how states should balance shared but differentiated responsibilities from a perspective of justice, equity, and intersectionality. Specifically, the court will clarify the principles that guide states’ obligations to cooperate collectively and individually. It will also examine how states should ensure the right to reparations for damages caused by their actions or omissions in the context of the climate emergency.

Meanwhile, the ICJ’s advisory opinion request presents a broader legal framework for states’ obligations under international law to protect the climate system from anthropogenic emissions. The General Assembly’s request explicitly asks the ICJ to consider the legal consequences for states that have caused “significant harm to the climate system,” particularly regarding states that are especially vulnerable to climate impacts.

Unlike the 2024 ITLOS Opinion, which clarified that it could not address liability for marine environmental damage due to the insufficiently formulated questions presented for consideration, the ICJ ruling could set clearer legal consequences for states’ actions or omissions, potentially reshaping international climate law by addressing accountability and reparation mechanisms. As we approach COP 29, the ICJ decision may mark a new moment in global climate governance, especially regarding the legal responsibilities of major emitting countries.

Conclusion

The principle of CBDR-RC is an important aspect of the international climate regime that recognizes historic and continuing economic inequality and the disproportionate impacts of climate change among developed and developing countries. Whether countries with emerging economies should contribute more to financial mechanisms, owing to their increasing GHG contributions, is set to be a contentious issue at COP 29 and, likely, beyond. Speed in coming to an agreement is key as delays and stalemates in climate financing ultimately harm the developing countries in need of substantial amounts of rapidly deployed funds the most.

Shifting away from a rigid dichotomy in the application of CBDR-RC recognizes that global development, and in turn greenhouse gas emissions, is not stagnant—as countries increasingly develop and emit, they must also increasingly contribute to mitigation efforts. While many deem COP 29 the “Finance COP,” the underscoring of almost all negotiations by the principle of CBDR-RC truly makes this the “CBDR COP.” And while the principle CBDR-RC will continue to influence conversations in relation to finance mechanisms, we can expect to see more countries— both developed and developing—engaging in climate action through mitigation but increasingly through adaptation efforts as the impacts of climate change begin to be increasingly felt.