The authors of this discussion paper consider linkage among heterogeneous climate-change policies — moving beyond relatively simple linkage among emissions-trading systems — in the context of the emerging Paris-Agreement regime. A Harvard Project event at COP-23 will draw upon this paper.

Martin Weitzman explores theoretically how international cooperation (democratic voting and/or negotiation) to set a global carbon price might incentivize mitigation and yield a global price that approximates an economically-efficient "social cost of carbon."

The 2015 Paris Agreement completed the transition to pledge-and-review as the core of the multilateral climate policy architecture. With ambitious long-term temperature goals and country-specific emission mitigation pledges set through 2030, the unfinished business coming out of the Paris talks is the design and implementation of the climate transparency mechanism. This paper reviews the poor transparency track record under the UN Framework Convention on Climate Change, and uses this performance to motivate engagement of non-stakeholders to enhance the rigor of the information and analysis of countries' emission mitigation efforts.

The Harvard Project releases a collection of expert briefs on the elaboration of the Paris Agreement.

The emerging pledge and review approach to international climate policy provides countries with substantial discretion in how they craft their intended emission mitigation contributions. The resulting heterogeneity in mitigation pledges places significant demands for a well-functioning transparency and review mechanism. In particular, the specific forms of intended contributions necessitate economic analysis in order to estimate the aggregate effects of these contributions as well as to permit "apples-to-apples" comparisons of mitigation efforts. This paper discusses the tools that can inform such analyses as well as the institutional needs of climate transparency.

The authors explore several approaches to an ambitious climate agreement in Paris in late 2015—including through carbon pricing.

Linkage among emissions-reduction systems can reduce cost and advance equity, enhancing the chances for success of a new 2015 climate agreement.

The Harvard Project co-sponsored a research workshop in May 2013 examining options for the UNFCCC's Durban-Platform process. This Issue Brief draws from and extends the discussion at the workshop.

The authors, using data from the recent history of international climate policy to test organizational ecology theory, attempt to explain changes in diversity, growth rates, and composition of organizations dealing with global climate change.

A treaty satisfies what we call International Paretianism if it advances the interests of all states that join it, so that no state is made worse off. The principle might seem obvious, but it rules out nearly all the major proposals for a climate treaty, including proposals advanced by academics and by government officials. We defend International Paretianism, and for that reason urge commentators in the debate over climate justice to abandon efforts to right past wrongs, redistribute wealth, and achieve other abstract ideals through a climate treaty