Squaring the circle of mitigation adequacy and equity: Options and perspectives

The Ad Hoc Working Group on the Durban Platform for Enhanced Action (ADP) aims to "develop a protocol, another legal instrument or an agreed outcome with legal force under the Convention applicable to all Parties", ready for adoption by the end of 2015. In this report we evaluate available options for a variety of aspects around the differentiation of mitigation commitments. We find that for the level of participation, the selection of commitment types, and choice of effort-sharing approaches there is no silver bullet. A portfolio approach that incorporates multiple options may be most suited to ensure environmental effectiveness, cost-effectiveness and political feasibility. Decisions taken at the 2013 climate conference in Warsaw set the process to arrive at differentiated mitigation commitments by 2015 on a path towards a mostly bottom-up approach, with perhaps some international discussion of Parties' initial offers. This is unlikely to deliver the required level of aggregate ambition to limit warming below 2°C - or even 1.5°C. There is still a window of opportunity to define a review process during 2014 that would enable a rigorous evaluation of initial offers and create the political pressure to enhance ambition. The summit organised by UN Secretary-General Ban Ki Moon in 2014 will be an important milestone in this process. Key to ensure political pressure is that the most vulnerable - and least responsible for the problem - are able to impact the decision on the overall level of commitments. This requires a process that involves reaching a joint agreement. However, even with a rigorous review process and the need to reach joint agreement, commitments are unlikely to be sufficient. Ultimately the conscious consideration of the length of the commitment period and a formal process for regular review of commitments will be crucial to ensure ambition can be ramped up suitably fast.