The Paris Agreement to the United Nations Framework Convention on Climate Change has achieved one of two key necessary conditions for ultimate success—a broad base of participation among the countries of the world. But another key necessary condition has yet to be achieved—adequate collective ambition of the individual nationally determined contributions. How can the climate negotiators provide a structure that will include incentives to increase ambition over time? An important part of the answer can be international linkage of regional, national, and sub-national policies, that is, formal recognition of emission reductions undertaken in another jurisdiction for the purpose of meeting a Party’s own mitigation objectives. A central challenge is how to facilitate such linkage in the context of the very great heterogeneity that characterizes climate policies along five dimensions: type of policy instrument, level of government jurisdiction, status of that jurisdiction under the Paris Agreement, nature of the policy instrument’s target, and the nature along several dimensions of each Party’s Nationally Determined Contribution. We consider such heterogeneity among policies, and identify which linkages of various combinations of characteristics are feasible; of these, which are most promising; and what accounting mechanisms would make the operation of respective linkages consistent with the Paris Agreement. 

On December 19, 2017, the government of China announced that it is commencing development of a nationwide CO2 trading system, that when launched will become the world’s largest carbon trading system, annually covering about 3.5 billion tons of CO2 emissions in China’s electric power sector. That approaches twice the size of what is currently the … Continue reading "What Should We Make of China’s Announcement of a National CO2 Trading System?"

This paper introduces an approach for separately quantifying the contributions from renewables in decomposition analysis. So far, decomposition analyses of the drivers of national CO2 emissions have typically considered the combined energy mix as an explanatory factor without an explicit consideration or separation of renewables. As the cost of renewables continues to decrease, it becomes increasingly relevant to track their role in CO2 emission trends. Index decomposition analysis, in particular, provides a simple approach for doing so using publicly available data. We look to the U.S. as a case study, highlighting differences with the more detailed but also more complex structural decomposition analysis. Between 2007 and 2013, U.S. CO2 emissions decreased by around 10%—a decline not seen since the oil crisis of 1979. Prior analyses have identified the shale gas boom and the economic recession as the main explanatory factors. However, by decomposing the fuel mix effect, we conclude that renewables played an equally important role as natural gas in reducing CO2 emissions between 2007 and 2013: renewables decreased total emissions by 2.3–3.3%, roughly matching the 2.5–3.6% contribution from the shift to natural gas, compared with 0.6–1.5% for nuclear energy.

Pricing greenhouse gas emissions involves making trade-offs between consumption today and unknown damages in the (distant) future. The optimal carbon dioxide (CO2) price, thus, is based on society’s willingness to substitute consumption across time and across uncertain states of nature. Standard constant relative risk aversion preference specifications conflate the two. Moreover, they are inconsistent with observed asset valuations, based on a large body of work in macroeconomics and finance. This literature has developed a richer set of preferences that are more consistent with asset price behavior and separate risk across time and across states of nature. In this paper, we explore the implications of these richer preference specifications for the optimal CO2 price. We develop the EZ-Climate model, a simple discrete-time optimization model in which the representative agent has an Epstein-Zin preference specification, and in which uncertainty about the effect of CO2 emissions on global temperature and on eventual damages is gradually resolved over time. We embed a number of features including potential tail risk, exogenous and endogenous technological change, and backstop technologies. The EZ-Climate model suggests a high optimal carbon price today that is expected to decline over time as uncertainty about the damages is resolved. It also points to the importance of backstop technologies and to very large deadweight costs of delay. We decompose the optimal carbon price into two components: expected discounted damages and the risk premium. JEL code: D81, G11, Q54.

This article presents an overview of the design and performance of seven major emissions trading programs that have been implemented over the past 30 years and identifies a number of important lessons for future applications of this important environmental policy instrument. A brief discussion of several other proposed or implemented emissions trading programs is also included.

The Paris Agreement has achieved one of two key necessary conditions for ultimate success – a broad base of participation among the countries of the world.  But another key necessary condition has yet to be achieved – adequate collective ambition of the individual nationally determined contributions. How can the climate negotiators provide a structure that will include incentives to increase ambition over time?    An important part of the answer can be international linkage of regional, national, and sub‐ national policies, that is, formal recognition of emission reductions undertaken in another jurisdiction for the purpose of meeting a Party’s own mitigation objectives. A central challenge is how to facilitate such linkage in the context of the very great heterogeneity that characterizes climate policies along five dimensions – type of policy instrument; level of government jurisdiction; status of that jurisdiction under the Paris Agreement; nature of the policy instrument’s target; and the nature along several dimensions of each Party’s Nationally Determined Contribution.  We consider such heterogeneity among policies, and identify which linkages of various combinations of characteristics are feasible; of these, which are most promising; and what accounting mechanisms would make the operation of respective linkages consistent with the Paris Agreement.

Inadequate policy surveillance has undermined the effectiveness of multilateral climate agreements. To illustrate an alternative approach to transparency, I evaluate policy surveillance under the 2009 G-20 fossil fuel subsidies agreement. The Leaders of the Group of 20 nations tasked their energy and finance ministers to identify and phase-out fossil fuel subsidies. The G-20 leaders agreed to submit their subsidy reform strategies to peer review and to independent expert review conducted by international organizations. This process of developed and developing countries pledging to pursue the same policy objective, designing and publicizing implementation plans, and subjecting plans and performance to review by international organizations differs considerably from the historic approach under the UN Framework Convention on Climate Change. This paper draws lessons from the fossil fuel subsidies agreement for climate policy surveillance.

Top-down climate negotiations embodied by the Kyoto Protocol have all but stalled, chiefly because of disagreements over targets and objections to financial transfers. To avoid those problems, many have shifted their focus to linkage of bottom-up climate policies such as regional carbon markets. This approach is appealing, but we identify four obstacles to successful linkage: different levels of ambition; competing domestic policy objectives; objections to financial transfers; and the difficulty of close regulatory coordination. Even with a more decentralized approach, overcoming the 'global warming gridlock' of the intergovernmental negotiations will require close international coordination. We demonstrate how a balance of bottom-up and top-down elements can create a path toward an effective global climate architecture.