The principle of “common but differentiated responsibilities and respective capabilities” (CBDR), which has been enshrined in the United Nations Framework Convention on Climate Change since 1992 (the Rio Earth Summit and the creation of the UNFCCC), refers to the issue of equity within a goal of universality: all countries must contribute to the protection of the environment and to the construction of sustainable development; but in order to achieve this goal, consideration must be given to the fact that some countries have played a greater part in environmental degradation and that disparities exist in the resources available to countries for the pursuit of this goal.

The Kyoto Protocol (1997) translated this principle by defining two categories of countries: the developed countries (Annexe 1), which are obliged to reduce their emissions; and the developing countries (Non-Annex 1), which must report their emissions. The CBDR principle, which has been interpreted in many different ways (from a moral, philosophical or even legal perspective), has thus assumed a dividing (geo)political dimension. Partly based on an “offence versus penalty” type of approach, in almost 20 years of post-Kyoto climate negotiations its implementation has proven to be particularly sensitive and challenging.

The problem appears to be insoluble. The Parties remain entrenched in irreconcilable positions: some Southern countries insist on the unquestionable historical responsibility of the Northern countries, enshrined in the text of the Climate Convention, which they believe justifies their (greater) “condemnation” for their contribution to climate change ; the latter, on the other hand, stress global changes that have occurred since the division between Annexe I and Non-Annex I countries, changes of an essentially economic nature that could modify the distribution and scope if not of “penalties”, then at least of “compensation”. At the same time, in order to implement the Rio Convention objective (in other words preventing climate change that jeopardises the development of human societies), a rapid and drastic reduction in emissions from industrialised countries (which should be close to zero by the middle of the century) must be achieved; it is also essential to define and implement solutions for a different, sustainable form of economic development in developing countries, failing which their emissions alone will invalidate the 2°C goal, to the detriment of the most vulnerable populations.

The challenges of COP21 include the need for the Paris agreement and its signatory parties to validate and stimulate the required transition towards a low-carbon world economy, which is the only way of limiting the impacts of climate change. In this context, the burden of responsibilities implied in the CBDR principle must evolve from “guilt” for having polluted in the past to an obligation to no longer pollute: historical and present responsibility becomes a commitment to the future. Against this background, the countries that historically produced the most emissions and benefited from fossil fuels to achieve a higher level of development than other countries consequently have a responsibility to contribute to this transition in a fair and proportionate manner. Equity therefore loses its punitive dimension and becomes a matter of – differentiated – cooperation towards a common goal.

This new approach to the CBDR principle accompanies and endorses a paradigm shift defined by all Parties themselves in their national contributions submitted ahead of COP21 (INDCs): the gradual phase-out of fossil fuels in favour of low-carbon power, with the goal of limiting global warming to 2°C by 2100. National decarbonisation strategies have replaced burden sharing for emissions reductions: the different countries no longer have an interest in doing nothing in order to avoid constraint, but must consolidate their transition through international cooperation. National contributions, which are drawn up for action at the national level, must therefore be included in the Paris agreement, whose fair and effective implementation depends on guarantees of cooperation and solidarity in collective action.

The concept of responsibility now needs to develop from this new basis for climate action, and should no longer be seen as a form of bullying by some or as a manoeuvre by others, but rather as momentum towards a more sustainable form of development. Our shared responsibility is to initiate, in all contexts and all countries, the transition towards a new development model. This is the assertion made by the majority of countries that submitted their national contributions in Paris. But our differentiated responsibility is, for the industrialised (rich) countries, to use the (disparate) resources available to us to achieve this transition, to make it more ambitious in our own countries and viable in all countries.