تجارت جهانی در مقابل ایجاد ارتباط : معماری برای انتشار تجارت بین المللی

International emissions trading is widely seen as an indispensable policy pillar of climate change mitigation [Stern, N., 2007. The Economics of Climate Change. The Stern Review. Cambridge University Press, New York]. This article analyzes five different types of trading architectures, classified into two top–down (UNFCCC driven) and three bottom–up (driven by individual countries or regions) approaches. The two types of approaches are characterized by a trade-off between environmental effectiveness and political feasibility, respectively, whereas their relative cost-effectiveness depends on implementation details. Bottom–up architectures constitute imperfect substitutes for top–down architectures in terms of environmental effectiveness, and thus remain mere fallback options. However, especially the ‘formal linking’ architecture can act as complement in terms of cost-effectiveness.

The last years have witnessed a considerable amount of political activity geared towards the establishment of emissions trading systems. Amongst other things, this reflects the fact that emissions trading is generally seen as an indispensable pillar of climate change mitigation, and is expected to constitute a key building block of future international climate policy (e.g. Stern, 2007). The Kyoto Protocol and the Marrakesh Accords established an inter-governmental trading system that is set to run for five years, from 2008 until the end of 2012. On this market, which covers the emissions of 37 states, representing 29% of the world's CO2 emissions in 2004 (CAIT, 2008),1 governments can trade emission permits—here called Assigned Amount Units (AAU)—which in principle allows to minimize the costs of compliance with their Kyoto reduction targets. They can also use credits generated under the Joint Implementation (JI) and Clean Development Mechanisms (CDM). Even earlier, in 2005, the European Union launched its emission trading system (EU ETS), which regulates about 10,000 facilities that currently emit around 2 Gt of CO2 per year (Skjaerseth and Wettestad, 2008). With a value of 50 bn US$ the EU ETS dominates the international carbon market, which totaled to 64 bn US$ in 2007 (Capoor and Ambrosi, 2008). EU policymakers have emphasized that, irrespective of the outcome of the UNFCCC negotiations on a post-Kyoto climate policy package, the EU ETS will remain in place even after 2012 (EU Council, 2007). Plans for the introduction of domestic emissions trading systems are also underway in several other Annex-I countries.2 These regional activities are flanked by the recent establishment of the International Carbon Action Partnership (ICAP), a forum that was created with the explicit intention of exploring the “(…) potential linkage of regional carbon markets” (ICAP, 2007). These developments can be understood as manifestations of two different approaches towards the establishment of emissions trading systems: first, there is the top-down approach, characterized by a centralized multilateral decision-making process and embodied in the UNFCCC negotiations. Second, there is the bottom-up approach, associated with decentralized decision-making of individual nations or sub-national entities that implement emissions trading systems uni-, bi- or plurilaterally (Zapfel and Vainio, 2002). These processes yield two different types of institutional architectures for international emissions trading. The backbone of ‘top-down’ architectures is emissions trading between governments, while ‘bottom-up’ architectures rest upon the implementation and possible linkage of regional systems, based on company-level emissions trading. This article aims to describe, analyze and compare these different institutional architectures.3 In the course of our analysis, we will argue that top-down and bottom-up architectures show characteristic differences in three key aspects. These are: • environmental effectiveness • cost-effectiveness • political feasibility Our main findings can be summarized as follows: because of their inclusiveness, top-down approaches tend to cover a larger share of global emissions and thus offer a higher degree of environmental effectiveness than bottom-up approaches. However, a significant share of global emissions could also be captured by means of a decentralized approach, in which a carbon market is created by linking existing domestic or regional ETS. The environmental effectiveness of both approaches can be enhanced by integrating baseline-and-credit schemes, e.g. the CDM of the Kyoto Protocol. If emissions price equalization is the sole criterion, top-down approaches also fare better in terms of economic effectiveness. But if plausible market imperfections associated with emissions trade between governments (such as market power or information asymmetries) are taken into account, price equalization is unlikely to be a sufficient criterion for efficiency, which requires the equalization of marginal abatement costs. Bottom-up approaches, based on preexisting trading systems between companies, provide a more robust price signal, and can be very efficient once they are ‘linked’. High political feasibility emerges as the main strength of bottom-up approaches, and, at the same time, biggest hurdle for top-down architectures. For the latter, a full international agreement on burden-sharing constitutes a condition sine qua non, while the former lends itself to the formation of a coalition-of-the-willing with subsequent enlargements. We conclude that the apparantly intuitive view of bottom-up and top-down approaches as (imperfect) substitutes needs to be amended. In as much as bottom-up trading architectures bring about not the optimal, but the feasible, they remain a second-best alternative to a top-down global cap-and-trade system in terms of environmental effectiveness. However, when viewed as building blocks that allow putting a cost-effective and expandable carbon market into place without further delay, their supportive role in the eventual establishment of a global carbon market becomes apparent. The remainder of our contribution is organized as follows: we begin in Section 2 by addressing questions of terminology and definition. Top-down architectures are described and analyzed in Section 3, bottom-up architectures are dealt with in Section 4. A comparative analysis and discussion are given in Section 5. We summarize our findings and present our conclusion in Section 6.

A comprehensive global system represents the benchmark for any future international emissions trading architecture, at least in terms of effective climate protection and access to low-cost abatement opportunities. However, given the considerable poli- tical challenge posed by top-down approaches — well reflected in the current multilateral climate policy negotiations — they suffer from the risk of a political deadlock of indeterminate duration. On the other hand, the bottom-up road to international emissions trading is constantly challenged by the question of whether emission reductions in this context can have a significant environmental impact at all. Still, this institutional approach may better suit the current state of politics, and therefore could help to bring about not the ideal but at least the feasible. Also, permit trade among companies is preferable to permit trade among governments on efficiency grounds, since distortions due to high market concentration are avoided and the liquidity and transpar- ency of the emerging emissions market are reinforced. By linking up with countries that have similar export profiles, leakage concerns can be mitigated at least partially. Suitably designed, bottom-up approaches enable a gradual integration of initially fragmented trading architectures, resulting in increasing environ- mental and cost-effectiveness. They allow countries to join whenever they feel ready, or whenever the political momentum in the country reaches a sufficient level. If top-down and bottom-up approaches are seen as comple- ments rather than substitutes, following both tracks in parallel via UNFCCC and ICAP appears to be a robust strategy, especially in view of the current uncertainty surrounding the multilateral climate policy negotiations. In case of a break-down of the latter, bottom-up linking of regional trading systems stands ready as a fallback option and alternative to the continuation of the Kyoto trading system. In any case, integrated trading architectures imply considerable challenges to international coordination, particularly regarding joint regulation. Therefore, exploring governance op- tions for carbon market regulation in multilateral architectures should be a key objective for further research on international emissions trading.