This symposium collection in Transnational Environmental Law (TEL) considers prospects for progress on global climate change policy under the assumption that the United States (US), or another critical national actor, will not meaningfully participate in any international climate change mitigation regime. Almost without exception lawmakers, diplomats, academics, and other interested parties discuss global climate change policy under the assumption that robust US participation is necessary to achieve success – an understandable view, given that as much as 20% of annual global greenhouse gas (GHG) emissions are attributable to the US.^{Footnote 1} Meanwhile, for the better part of the last two decades, US ambivalence and at times outright hostility towards climate change policy have impeded the development of a robust international regime. The national US political situation – from the disincentives for bipartisan compromise in a winner-takes-all two-party system, to the de facto super-majority requirement for the passage of legislative bills in the Senate, to the contorted alignment necessary to secure agreement between the House, the Senate and the President – make it reasonable to wonder if the US could ever adopt the kinds of robust and transformative policy declared to be necessary by much of the climate change policy community.

In light of such challenges, a growing number of observers are now asking if it still makes sense for the rest of the world to wait for the US to lead in the climate arena. Indeed, in response to mounting frustration over the role of the US in international climate talks, former US Under-Secretary of State for Global Affairs Frank Loy noted that ‘some are asking something even more fundamental: Is the US governable?’.^{Footnote 2} The international community has spent nearly two decades pursuing modest goals while holding off for deep US commitment; the climate crisis, they argue, can bear no further delay. In an effort to confront this stalemate squarely and creatively, a conference was held at Yale Law School in November 2012 entitled ‘Global Climate Change Policy Without the United States: Thinking the Unthinkable’. The conference brought together international experts to envision a range of climate change policy scenarios in which the US is assumed not to be an ardently engaged participant. The goal of this symposium collection extends from the conference objectives. Firstly, it attempts to investigate alternative scenarios for responding to the climate problem without the cooperation of a major global player. Taking for granted that the US or another major political actor will exhibit non-participation or non-compliance, this symposium collection explores the viability of alternative policy pathways under this constraint. Secondly, and more broadly, it aims to foster intellectual development within the field of environmental law and policy by forcing the field to confront political scenarios that many experts have simply assumed are fatal to climate progress. An abundant field of scholarship attempts to identify the design features of an effective multilateral climate policy regime or international agreement,^{Footnote 3} but the articles in this symposium collection investigate, instead, the legal and political channels for a global climate change ‘Plan B’ – that is, an investigation of how climate change might be addressed assuming a lack of strong leadership or participation by the US or a similarly critical national actor.

To be sure, recent developments challenge, at least on the surface, the premise of the November 2012 conference from which this symposium collection originates, as signs of a shift in US climate policy have emerged. In February 2013, during his State of the Union Address, for instance, President Barack Obama urged a bipartisan and market-based response to climate change, given the Congressional failure to enact climate legislation.^{Footnote 4} Subsequently, in June 2013, the President unveiled a Climate Action Plan, which directs the US Environmental Protection Agency (EPA) to establish carbon pollution standards for power plants and recommits the US to its ‘Copenhagen targets’.^{Footnote 5} In July 2013, a US-China Climate Change Working Group was formed with the goal of reducing GHG emissions and air pollution by tackling the largest sources of emissions in both countries.^{Footnote 6} Finally, the President has embraced an era of administrative agency action in the climate change context as a result of the failure of the US Congress to address the problem through new comprehensive legislation.^{Footnote 7} Michael Gerrard and Shelley Welton discuss these and other developments in US national climate change law and policy in their invited commentary.^{Footnote 8} Such developments may credibly portend a substantively different approach to climate change policy in the US, one that will be recognized as such by other nations and that will alter the diplomatic stalemate that has characterized international climate negotiations for nearly two decades.

For this reason, it is important to clarify that the articles in this symposium collection are not limited to non-participation by the US alone; various other countries can be viewed as coming within the ‘defiant or defective actor’ scenario. A climate policy regime without, for example, Japan, Canada, New Zealand, or the Russian Federation should also be considered as these countries have all signalled their intention to abandon the second commitment period under the Kyoto Protocol.^{Footnote 9} Changing economic and geopolitical dynamics have also given rise to a class of major emitting emerging economies, which include India, China and Brazil, whose participation is seen as decisive to the success of any multilateral mitigation scheme, yet whose negotiating bodies have thus far been reluctant to commit to substantial emissions cuts. The US is therefore referred to in this symposium collection foremost as a symbolic device, capturing the dynamic in which a dominant actor presents a roadblock to international consensus or policy breakthrough.

An additional qualification bears noting. An entire country’s response to climate change often cannot be fairly characterized as a coherent, univocal whole in the fashion presumed (or desired) by international lawmakers. Within the US, for example, a range of municipal, state and regional level climate initiatives have emerged as evidence of the tiered and multivalent nature of domestic law and politics, including notably the Mayors Climate Protection Agreement,^{Footnote 10} the Regional Greenhouse Gas Initiative (RGGI),^{Footnote 11} and the comprehensive and potentially world-leading suite of reforms adopted by the state of California,^{Footnote 12} including the state’s recent agreement with China to collaborate on clean energy and climate change.^{Footnote 13} Despite this polycentric nature of US governance, the nation’s climate policy on the world stage is frequently believed to require a kind of ‘crystallization’ at the national level – paradigmatically, a moment when the US Senate ratifies a treaty that is backed by legislation passed by both houses of Congress and signed by the President. When the conference organizers raised the notion of climate policy without the US, they had in mind climate policy that lacks this paradigmatic involvement. Two articles in this collection instead draw attention to the variety of non-traditional loci of climate policy, and make important suggestions for how to leverage their power more effectively.^{Footnote 14}

The articles in this collection are organized into three thematic categories. The first category examines the potential for states to make an end run around uncooperative negotiating partners by going outside the United Nations Framework Convention on Climate Change (UNFCCC)^{Footnote 15} process to bodies like the World Trade Organization (WTO) and the International Court of Justice (ICJ); the second identifies the potential to bypass ineffectual state actors and legislative veto points; the third considers the potential for a more radical ‘Plan B’ under climate engineering schemes. Throughout this foreword we also refer to conference speeches made by Robert Howse, Richard Stewart, Bernarditas de Castro-Muller, Jane C.S. Long, and Robert Socolow, whose conference contributions complement the findings in the articles included in this collection.^{Footnote 16}

The first article by Ambassador Stuart Beck and Elizabeth Burleson reflects on Palau’s campaign to request an advisory opinion from the ICJ regarding the reciprocal obligations of states in the domain of climate change.^{Footnote 17} The purpose of the advisory opinion would be to clarify the obligations of a state to ensure that its emissions do not cause or substantially contribute to climate-related harm in another state.^{Footnote 18} Prior to its ICJ campaign, Palau also led a United Nations (UN) General Assembly initiative requesting UN organs, including especially the powerful Security Council, to acknowledge and address the security implications of climate change.^{Footnote 19} Both of these campaigns were motivated by the country’s less than optimistic prognosis for the UNFCCC: in the view of Palau’s representatives, protracted negotiations under the Durban Platform^{Footnote 20} and consensus-based proceedings practically guarantee inaction before 2020 (or, as the Ambassador noted, is like having a defendant on the very jury that needs unanimity for that defendant’s conviction). While Palau’s efforts have generated disapproval from US representatives, it has also received widespread support from countries similarly desirous of a more relevant and reaching international legal apparatus. Because the advisory opinion function of the ICJ does not require consent by individual states as parties, the campaign also represents an effort to circumvent the perceived obstructionism of a dominant state actor in the political negotiating arena.

In a similar vein, in his conference remarks Robert Howse investigated the legality and legitimacy of a state taking unilateral measures to address the failure of other states to regulate carbon emissions; in particular, he asked if border tax adjustments and similar regulatory measures could be compliant with the General Agreement on Tariffs and Trade (GATT)^{Footnote 21} and related WTO agreements. A common claim is that a state cannot regulate global environmental externalities unless the target of such regulation remains within the state’s boundaries, but Howse considered the design features of regulatory and tax-based adjustments that could enhance WTO compliance, including even-handedness in the treatment of imported goods for non-discrimination. While border adjustments can be designed towards WTO compliance, in Howse’s view, countries that stand the most to lose will question the even-handedness of any given scheme, no matter how well designed. Because domestic constituencies may be expected to lobby for border adjustments to be adopted in a manner that confers ancillary protectionist benefits, Howse concluded that the politics of climate mitigation may be the greatest hurdle for a smooth reception of trade-related environmental measures at the WTO, rather than the economics or the law.

The articles in this collection by Daniel Farber^{Footnote 22} and Kenneth Abbott^{Footnote 23} both explore the second theme, and are connected in their attempt to consider the potential for the US to be a global player, even if it is not a united one. Daniel Farber engages this field by studying carbon leakage and the prospect for policymakers to combat leakage through jurisdictional linkage. He asserts that US sub-national governments and the federal executive branch can propose climate policies to circumvent an ineffectual Congress but, in doing so, they are likely to encounter a range of constitutional challenges including those under the dormant commerce clause, the compact clause, or the foreign affairs pre-emption doctrines of US constitutional law. On balance, he concludes that these challenges should not prevent an effective response from state governments and the executive branch; the US EPA has some statutory authority to deal with carbon leakage and the President is likely to have authority to establish regulatory linkages with foreign mitigation efforts. Ultimately, however, Farber concludes that the state and executive channels are still limited to reducing emissions ‘at the margins’ until there is a credible response from Congress.^{Footnote 24}

Abbott declares from the outset that multilateral climate policy – centred on consensus and comprehensive outcomes – cannot on its own produce an effective and timely response. His article identifies the promise of a strengthened transnational climate change regime, which could generate climate governance innovations across a loosely connected group of non-state actors and institutions. The goal of this regime is to allow non-state actors – from business firms to city governments – to bypass and manage the behaviour of states. Although the regime is weak in its current form, it could be strengthened by increasing the level of coordination and collaboration among constituent institutions while remaining polycentric. Regime innovation could generate governance activity typically expected from states, such as setting standards for measuring and reporting emissions and offsets, financing and managing renewable energy projects, and disseminating information that fosters organizational learning. Ideally, Abbott notes, a strengthened transnational climate change regime will complement the efforts made by states, but it can also operate independently, helping to partially fill the governance gap left by states.^{Footnote 25}

During his conference lecture, Richard Stewart similarly examined the potential for smaller scale and less centralized forms of transnational climate cooperation to occur alongside the lagging UNFCCC process. Stewart introduced a ‘building blocks’ strategy as an innovative institutional approach to climate action, which is further explained in his subsequently published article with Michael Oppenheimer and Bryce Rudyk.^{Footnote 26} The building blocks consist of different institutional strategies to promote specialized regimes among governments, sub-national jurisdictions, the private sector, and non-governmental organizations (NGOs) to reduce GHG emissions. To encourage participation, the building blocks aim primarily to pursue non-climate objectives that offer ancillary climate benefits. This approach avoids the inherent problem of motivating nations to support the provision of a global public good by targeting other interests – such as economic self-interest, energy security, the reduction of co-pollutants, and the promotion of international development – that may incidentally entail the reduction of GHG emissions. Stewart and his co-authors argue that the building blocks approach may promote global climate action both by encouraging short-term emissions reductions and by creating transnational webs of cooperation and trust that may ultimately help the achievement of a full-throated ‘Plan A’ multilateral climate treaty.

A career diplomat from the Philippines, Bernarditas de Castro-Muller, provided another perspective during the conference proceedings on the potential to bypass ineffectual state actors. While the multilateral response to the climate problem may not be sufficient on its own, de Castro-Muller explained why such a response remains essential for a truly durable international climate regime: the UNFCCC provides the only policy pathway anchored in principles of equity and common but differentiated responsibilities. She cautioned that a ‘flexible’ multilateral response, which has been promoted by the US, may undermine this principle-based framework. The discussions by Abbott, Stewart, and de Castro-Muller on climate governance reveal the tension between wanting to solve the climate problem fast and wanting to solve it fairly. Much of the discussion during the conference proceedings questioned whether a window may exist for both models to converge into a transnational climate change regime that can be used to inform, rather than detract from, a principle-based framework.

The article by Edward Parson^{Footnote 27} explores the third issue theme in this symposium collection, and considers the potential for a more radical ‘Plan B’, through the use of climate engineering techniques, popularly known as geoengineering. As Parson notes, climate policy options are not limited to mitigation pathways but might also include the modification of the global environment to address heating and climate disruptions caused by climate change and the failure to mitigate. Parson examines how the addition of climate engineering to the climate policy agenda affects incentives for participation and non-participation, thereby introducing novel challenges and opportunities for the international climate regime.^{Footnote 28} Climate engineering governance scenarios need not be sealed off from the dominant mitigation approach; indeed, Parson elaborates on four arrangements for explicit bargaining linkages between climate engineering and mitigation responses. Under a Plan B linkage, for instance, states pursue mitigation while undertaking climate engineering research; under a reverse linkage, states deploy climate engineering strategies only if mitigation efforts succeed; under a real-time linkage, mitigation and climate engineering are pursued in parallel; and under a ‘pay to play’ linkage, mitigation is a condition for participation in climate engineering decision-making. Of all these arrangements, Parson considers the feasibility for real-time linkage when used earlier and at lower intensity to help to reduce the peak of near-term heating and target regional processes.

During her conference presentation on geoengineering, Jane C.S. Long examined the near-term governance potential for geoengineering research and its potential to generate longer-term governance norms. In her view, the US could be proactive in geoengineering research by developing a coordinated research programme and establishing an advisory commission to consider research governance challenges in greater detail.^{Footnote 29} A framework for research governance could facilitate the US government’s response to research experiments already undertaken by countries and private entities. More generally, and perhaps importantly, Long argued that early efforts towards research governance could help to condition governments to develop early habits of working together. Such early efforts for research governance would generate an ethos of collaboration and consultation as geoengineering research continues, or if such schemes are eventually deployed.

The articles in this symposium collection delve into a range of plausible scenarios, given a recalcitrant but critical policy player in the climate change domain. Collectively, these articles contemplate the comparative effectiveness of different policy instruments and policy configurations when a major political player is assumed to be on the sidelines. The articles generate a range of questions, including why one should even consider a global climate change ‘Plan B’. Much as environmental activists once hesitated to discuss climate change adaptation out of fear that it would undermine political will to address mitigation, does the thought experiment posed by this conference generate a moral hazard by detailing alternative arrangements, which detract from the obligation and responsibility of key participants in the UNFCCC process? Will the prospect of alternative arrangements distract decision-makers away from the primary desideratum of a robust, rules-based mitigation regime?

During the conference, the closing keynote speaker, Robert Socolow, was reminded by a participant of a short comment written in 1970 in which Socolow contrasted two different levels of response to environmental calamities.^{Footnote 30} The first level involved simply responding to an identified environmental problem through technological and economic instruments, without questioning the underlying values, lifestyles and structures giving rise to the problem. This approach might be adequate for some marginal environmental challenges, but Socolow was worried about the grander challenge of harmonizing the desire for continuous economic growth with the reality of the Earth’s finite carrying capacity. For that deeper, second level of environmental challenge, Socolow in 1970 wrote the following words:

These words offer a remarkably succinct and prescient account of the climate change policy stalemate that has lasted for the two generations since they were written. The thought experiment posed by this conference and symposium collection has been motivated by the belief that the world cannot afford another generation of inaction.