In the climate change regime, equity and differentiation are two sides of a coin, symbolic concepts that involve comparison among countries. They cannot be addressed by logic alone. They carry political and emotional baggage, touching upon perceptions of national identity based on history and popular myth. Moreover, attitudes of negotiators towards these concepts are deeply rooted. For these reasons, any changes in conventional approaches to these concepts must be prudent, pragmatic and easy to understand. Such changes are already visible in the Lima Call for Climate Action.

Differentiation is the easier of the two concepts to address. There is no doubt that there must be some form of differentiation in the Paris agreement. Countries are different. The open questions are: differentiation applied to what and on what basis?

Traditionally, the conventional North-South donor-recipient differentiation has guided the approach to the provision and mobilisation of finance under the UNFCCC. However, the emergence of “complementary [financial] support by other Parties” is noted in the Lima Call (para. 4), as is the particular vulnerability of certain developing country recipients. A number of non-Annex II Parties have pledged contributions to the Green Climate Fund. In addition, South-South cooperation has a long history that is particularly relevant to capacity building, while the Convention clause on transfer of environmentally sound technologies (Article 4.5) provides that “other Parties … in a position to do so may also assist in facilitating the transfer of such technologies”. Thus, differentiation with respect to “means of implementation” is already nuanced. The difficult question is that of differentiation with respect to mitigation action (adaptation, in this context, being subsumed under finance).

The Lima Call provides the basis for self-differentiation with respect to mitigation action. It does not distinguish between different categories of Parties in their preparation and communication of “intended nationally-determined contributions” (INDCs). The key words with respect to the content of INDCs are “may include” (Lima Call, para. 14). In a sense, therefore, the question of differentiation of contributions to mitigation action has been settled for the time being, though such action is still to be carried out “under the Convention” that enjoins developed country Parties to “take the lead” and is to “represent a progression beyond the current undertaking of each Party” (Lima Call, para. 10).

Questions that remain open in the current debate include the possible application of differentiation to the legal character of the NDCs in the framework of the Paris Agreement, to the process of accountability (aka “transparency”) with respect to fulfilment of those pledges, to the duration and ambition of future cycles of pledges and to pathways towards a common long-term objective. Therefore, moving towards a unified system of accountability would give a strong political signal.

Equity is traditionally addressed as a question of fair burden sharing and thus – like differentiation – inspires defensive negotiating stances. This raises two big questions.

First, what is the “burden” to be shared? What is the quantified long-term objective to be achieved? Should this effort be shared “top down” or approached “bottom up”? (Clearly, the present political advantage is to the latter option.) The recent formulation by the IPCC of a quantified “carbon budget” for limiting global warming to 2°C gives a new edge to this debate.

Second, how can the burden-sharing approach be reconciled with the growing realisation that low-carbon investment is profitable? (cf. the Calderón report on the « New Climate Economy ») Or even with the positive concept of equitable access to sustainable development? Changing to a positive narrative on mitigation will transform the equity debate.

Both these questions focus on mitigation. An often-ignored aspect of equity is that doing nothing to limit GHG emissions, relying entirely on adaptation, is not only dangerous but also fundamentally unjust because of the uneven distribution of vulnerability around the globe.

Finally, ambition is a common feature in both debates. It is possible to negotiate an agreed outcome that is fair and suitably differentiated but utterly inadequate to meet the climate challenge. Ambition must remain the driver of action; approaches to equity and differentiation will orient pathways to the common goal.