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

The outcome of the December 2011 United Nations climate negotiations in Durban, South Africa, provides an important new opportunity to move toward an international climate policy architecture that is capable of delivering broad international participation and significant global CO2 emissions reductions at reasonable cost. We evaluate one important component of potential climate policy architecture for the post-Durban era: links among independent tradable permit systems for greenhouse gases.

"A successful international climate policy framework will have to meet two conditions, build a coalition of countries that is potentially effective and give each member country sufficient incentives to join and remain in this coalition. Such coalition should be capable of delivering ambitious emission reduction even if some countries do not take mitigation action. In addition, it should meet the target without exceedingly high mitigation costs and deliver a net benefit to member countries as a whole. The novel contribution of this paper is mostly methodological, but it also adds a better qualification of well-known results that are policy relevant."

In a new Harvard Project Discussion Paper, Fondazione Eni Enrico Mattei's Valentina Bosetti and Enrica De Cian model the behavior of countries not participating in a cooperative climate regime. The regime imposes counterbalancing influences upon these countries, but under some conditions they may act to both reduce emissions and increase clean-energy R&D

Market-approaches to reducing emissions of greenhouse gases lie at the heart of any cost-effective set of policies put forward in an international agreement—and will be considered at COP 17 in Durban in both the Kyoto and Long-term Cooperative Action discussions. Joseph Aldy and Robert Stavins "examine the opportunities and challenges associated with the major options for carbon pricing: carbon taxes, cap‐and‐trade, emission reduction credits, clean energy standards, and fossil fuel subsidy reductions."

Geoengineering grows in salience, the more time that passes without an effective international regime for mitigating climate change. It will be in the background of negotiations at COP 17 in Durban—and, perhaps, in the foreground of some important discussions. This discussion paper by Daniel Bodansky explores the opportunities and risks presented by geoengineering, as well as the particular challenges to crafting an effective system of governance for this set of approaches to addressing climate change

In pursuit of a workable successor to the Kyoto Protocol, this study offers a framework of formulas that produces precise numerical targets for emissions of carbon dioxide (CO2) and other greenhouse gases, in all regions of the world in all decades of this century....Firms, consumers, and researchers base their current decisions to invest in plant and equipment, consumer durables, or new technological possibilities on the expected future price of carbon: If government commitments are not credible from the start, then they will not raise the expected future carbon price.

In order to induce investment in research and development, incentive-based instruments such as emissions taxes and carbon cap and trade have to be expected to be in place after the new technology comes to market. This can be several years after the decision to invest in R & D is made. Policies announced or put in place today can be changed. To put it simply, there is a commitment problem. This commitment problem does not apply to policies put in place today that lower the cost of R & D, such as subsidies or complementary investments by public-sector entities. We compare the effects of an emissions tax, an emissions quota with tradeable permits, and R & D subsidies on a firm’s incentive to conduct R & D in the absence of commitment by the government.

This paper proposes a new architecture for international climate policy that might usefully be considered by delegates at COP 17 in Durban. It highlights a top-down approach that is designed to produce a fair distribution of burdens across countries, while achieving objectives of: (a) economic development; (b) decreasing wealth inequality; and (c) emission reductions consistent with holding the expected increase in global average temperature to 2 degrees Celsius. In addition, this discussion paper discusses several key design elements that will be important, especially from the perspective of developing countries, to the success of COP 17 and subsequent international climate negotiations. These design elements include agreements on burden sharing, choice of policy instruments, financial mechanisms and technology transfer, penalties for noncompliance, and linkages between trade and climate change.

Harvard Project Director Robert N. Stavins reviews economics research on open-access resources over the last century; the development of market-based policies to respond to commons problems; and the application of policy-relevant scholarship in economics to the "ultimate commons problem"—global climate change.