The concept of Common But Differentiated Responsibilities and Respective Capabilities (CBDR-RC) is a foundational principle of international environmental law, specifically within the global climate change regime. It is a concept that holds all states responsible for addressing human-driven climate change but acknowledges that their duties and abilities to act are different.
The principle's origin is in Principle 7 of the 1992 Rio Declaration on Environment and Development, and it was officially enshrined in Article 3, paragraph 1 of the 1992 United Nations Framework Convention on Climate Change (UNFCCC). It was created to solve the problem of unequal contribution to global environmental degradation and the disparity in economic and technological capacity to address it. The principle recognizes the greater historical responsibility of industrialized countries for the largest share of historical greenhouse gas emissions.
The mechanism of CBDR-RC works by establishing a distinction between countries, requiring different standards of conduct. Under the UNFCCC, this was initially a hardline dichotomy between Annex I Parties (developed countries and economies in transition) and Non-Annex I countries (developing countries). Article 3, paragraph 1 of the UNFCCC states that developed country Parties should "take the lead in combating climate change". The principle applies to areas like mitigation, adaptation, technology transfer, finance, and capacity building.
CBDR-RC connects most directly to the UNFCCC and the subsequent Paris Agreement of 2015. The Paris Agreement, which is a legally binding international treaty, explicitly references the principle in Article 2. The principle has changed recently, moving away from the static, bifurcated Annex I/Non-Annex I classification. The Paris Agreement introduced a more flexible approach, requiring all Parties to submit Nationally Determined Contributions (NDCs) on a five-year cycle, fulfilling the "common" element. However, the differentiation remains, as Article 4, paragraph 4 of the Paris Agreement expects developed countries to "take the lead by undertaking economy-wide absolute emission reduction targets," while developing countries are to continue enhancing their mitigation efforts "in the light of different national circumstances". The core idea of developed countries taking the lead and providing financial support remains the same.