Energy-efficient technologies offer considerable promise for reducing the financial costs and environmental damages associated with energy use, but these technologies appear not to be adopted by consumers and businesses to the degree that would apparently be justified, even on a purely financial basis. We present two complementary frameworks for understanding this so-called “energy paradox” or “energy-efficiency gap.” First, we build on the previous literature by dividing potential explanations for the energy-efficiency gap into three categories: market failures, behavioral anomalies, and model and measurement errors. Second, we posit that it is useful to think in terms of the fundamental elements of cost-minimizing energy-efficiency decisions. This provides a decomposition that organizes thinking around four questions. First, are product offerings and pricing economically efficient? Second, are energy operating costs inefficiently priced and/or understood? Third, are product choices cost-minimizing in present value terms? Fourth, do other costs inhibit more energy-efficient decisions? We review empirical evidence on these questions, with an emphasis on recent advances, and offer suggestions for future research.

On February 18-20, 2015, twenty-four experts gathered in Berlin to explore approaches to improving the process by which research on climate change is assessed – with a focus on the social-sciences (economics, political science, policy studies). The workshop was sponsored by the Fondazione Eni Enrico Mattei, the Harvard Project on Climate Agreements, the Mercator Research Institute on Global Commons and Climate Change, and the Stanford Environmental and Energy Policy Analysis Center. Leaders of three of the sponsoring organizations, Carlo Carraro (FEEM), Charles Kolstad (Stanford University), and Robert Stavins (Harvard Kennedy School), have prepared a memorandum drawing from the workshop. The memo describes the specific challenges and opportunities facing the Intergovernmental Panel on Climate Change (IPCC) and provides recommendations for improving the IPCC's process of assessing scientific research on climate change.

The last ten years have seen the growth of linkages between many of the world's cap-and-trade systems for GHGs, both directly between systems, and indirectly via connections to credit systems such as the Clean Development Mechanism. If nations have tried to act in their own self-interest, this proliferation of linkages implies that for many nations, the expected benefits of linkage outweighed expected costs. In this article, we draw on the past decade of experience with carbon markets to examine why systems have demonstrated this revealed preference for linking. Linkage is a multi-faceted policy decision that can be used by political jurisdictions to achieve a variety of objectives, and we find qualitative evidence that many economic, political, and strategic factors – ranging from geographic proximity to integrity of emissions reductions – influence the decision to link. We also identify some potentially important effects of linkage, such as loss of control over domestic carbon policies, which do not appear to have deterred real-world decisions to link.Policy relevanceThese findings have implications for the future role that decentralized linkages may play in international climate policy architecture. The Kyoto Protocol has entered what is probably its final commitment period, covering only a small fraction of global GHG emissions. Under the Durban Platform for Enhanced Action, negotiators may now gravitate toward a hybrid system, combining top-down elements for establishing targets with bottom-up elements of pledge-and-review tied to national policies and actions. The incentives for linking these national policies are likely to continue to produce direct connections among regional, national, and sub-national cap-and-trade systems. The growing network of decentralized, direct linkages among these systems may turn out to be a key part of a future hybrid climate policy architecture.

Improving end-use energy efficiency—that is, the energy-efficiency of individuals, households, and firms as they consume energy—is often cited as an important element in efforts to reduce greenhouse-gas (GHG) emissions. Arguments for improving energy efficiency usually rely on the idea that energy-efficient technologies will save end users money over time and thereby provide low-cost or no-cost options for reducing GHG emissions. However, some research suggests that energy-efficient technologies appear not to be adopted by consumers and businesses to the degree that would seem justified, even on a purely financial basis. We review in this paper the evidence for a range of explanations for this apparent "energy-efficiency gap." We find most explanations are grounded in sound economic theory, but the strength of empirical support for these explanations varies widely. Retrospective program evaluations suggest the cost of GHG abatement varies considerably across different energy-efficiency investments and can diverge substantially from the predictions of prospective models. Findings from research on the energy-efficiency gap could help policy makers generate social and private benefits from accelerating the diffusion of energy-efficient technologies—including reduction of GHG emissions.

Bilateral climate change negotiations between China and the US are the most significant development since the Kyoto Protocol

Negotiations pursuant to the Durban Platform for Enhanced Action appear likely to lead to a 2015 Paris agreement that embodies a hybrid climate policy architecture, combining top-down elements, such as for monitoring, reporting, and verification, with bottom-up elements, including “nationally determined contributions” from each participating country, detailing what it intends to do to reduce emissions, based on its national circumstances. For such a system to be cost-effective—and thus more likely to achieve significant global emissions reductions—a key feature will be linkages among regional, national, and sub-national climate policies. By linkage, we mean a formal recognition by a greenhouse gas mitigation program in one jurisdiction (a regional, national, or sub-national government) of emission reductions undertaken in another jurisdiction for purposes of complying with the first jurisdiction’s mitigation program. We examine how a future international policy architecture could help facilitate the growth and operation of a robust system of international linkages of regional, national, and sub-national policies. Several design elements merit serious consideration for inclusion in the Paris agreement, either directly or by establishing a process for subsequent international elaboration. At the same time, including detailed linkage rules in the core agreement is not desirable because this could make it difficult for rules to evolve in light of experience.