The UN Climate Summit and a Key Issue for the 2015 Paris Agreement

05/04/2015 02:44 pm ET | Updated May 04, 2016

World leaders converged at the United Nations in New York City this past week for Secretary-General Ban Ki-moon's much-anticipated Climate Summit, a lead-up to global negotiations that will take place in Lima, Peru, in December of this year and culminate a year later in Paris. The challenge before negotiators is great, because there are significant obstacles to reaching a meaningful agreement, as I describe in an op-ed that appeared in The New York Times on Sunday, Sept. 21, "Climate Realities."

However, partly because of the new path that is being taken under the Durban Platform for Enhanced Action, in which all countries will be included under a common legal framework in a politically realistic hybrid policy architecture, the prognosis for a meaningful international agreement is better now than it has been in decades. I discuss this briefly at the end of the Times op-ed and emphasize it in a follow-up op-ed that appeared in The Boston Globe on Sept. 23, "UN summit can accelerate momentum to a new approach to climate change." (Also, for my overall assessment of the UN Climate Summit, see this interview carried out by the Harvard Kennedy School's Doug Gavel.)

A New Development at the UN Climate Summit

The most significant development at the UN Climate Summit this past week was the degree to which carbon pricing became central to so many discussions, including with leaders from the business community. As carbon pricing -- in particular, cap-and-trade systems -- have emerged as the policy instrument of choice in many parts of the world, interest in linking these systems together has grown. Linkage (unilateral or bilateral recognition of allowances) among carbon markets -- and, for that matter, links with non-market-based systems -- can reduce the aggregate cost of achieving climate targets. And lower compliance costs can in turn encourage countries to increase the ambition of their contributions under the 2015 Paris agreement.

New Research From Harvard

Because of this, the Harvard Project on Climate Agreements has been collaborating with the International Emissions Trading Association (IETA) to explore the role of linkage in the new international climate change agreement to be completed in Paris. In this new research, my co-authors (Daniel Bodansky of Arizona State University, Seth Hoedl of Harvard Law School, and Gilbert Metcalf of Tufts University) and I examine linkage -- not only among cap-and-trade systems but among cap-and-trade, carbon-tax, and non-market regulatory systems -- and the role that linkage should play in the 2015 agreement. We look both at what would inhibit or even prevent linkage and should therefore be avoided in the 2015 agreement and what -- in a positive sense -- should be included in the agreement to facilitate effective linkage of regional, national, and sub-national climate policies.

We released an executive summary of our research paper ("Facilitating Linkage of Heterogeneous Regional, National, and Sub-National Policies Through a Future International Agreement") in New York City on Sept. 22 at an event co-sponsored by IETA and the Harvard Project, on the sidelines of UN Climate Summit, "Carbon Pricing and the 2015 Agreement." (The agenda of the event is available here).

In the executive summary (which can be downloaded in full here), we conclude that among the design elements the 2015 agreement should avoid because they would inhibit linkage are so-called "supplementarity requirements" that require parties to accomplish all (or a large, specified share) of their emissions-reduction commitments within their national borders. The 2015 agreement also should avoid including detailed linkage rules in the core agreement; an agreement with more flexibility would allow rules to evolve on the basis of experience.

Importantly, we also find that, to advance linkage, the 2015 agreement should: define key terms, in particular the units that are used for compliance purposes; establish registries and tracking mechanisms; and include default or model rules, from which nations are free to deviate at their discretion. Overall, the most valuable outcome of the Paris agreement regarding linkage may simply be including an explicit statement that parties may transfer portions of their emissions-reduction contributions to other parties -- and that these transferred units may be used by the transferees to implement their own commitments.

Looking Forward

We will release the complete research paper in November of this year, prior to the Twentieth Conference of the Parties (COP-20) of the United Nations Framework Convention on Climate Change in Lima, Peru, in December 2014, where the Harvard Project and IETA plan to conduct a side event that will focus on this work.

When the full paper is released in November, I will provide a more complete description at this blog of our research methods and our findings.

(Additional press coverage is here, here, here, here, here, here, here, here, here, and here.)