Given the urgency of the global environmental crisis, it is unsurprising that international relations (IR) scholarship on global environmental politics (GEP) is overwhelmingly presentist in nature. Faced with accelerating global warming and rapid biodiversity loss, GEP scholars have good reasons to focus on the here and now of global environmental protection efforts, be it in the form of intergovernmental negotiations or transnational action. But is there anything that we can we learn from the history of international environmental efforts? And if so, should students of GEP spend more time researching the origins and evolution of this international policy domain?

Recent years have witnessed a growing interest in the roots of international environmental diplomacy and global environmental action, not just among environmental and international historians but also in the IR discipline. These two books, although different in style and focus, demonstrate why viewing GEP through a historical lens can yield important insights into the successes and failures of international efforts to save the planet.

Michael Manulak’s book, Change in Global Environmental Politics, deals with the two big, epoch-defining events in the evolution of international environmentalism: the first UN environment conference in Stockholm in 1972 and the “Earth Summit” in Rio de Janeiro in 1992. He also examines other notable conferences that were less consequential, such as the 1982 UNEP Nairobi conference, the UN session debating the 1987 Brundtland Commission report, and the 2002 World Summit on Sustainable Development. His main research interest is in understanding why some of these high-level summits produced lasting institutional change while others failed to have the same effect.

Most explanations of profound institutional change in international relations focus on exogenous shocks (wars, economic crises), but these largely fail to explain the emergence of international environmental politics in the early 1970s and the acceleration and shift in international environmental institution building in the early 1990s. Manulak’s book offers a different explanation, one that points to the ability of international actors to produce lasting international change out of gradual but significant shifts in international contexts. Historical institutionalists would have us believe that, without external shocks, actors are locked into a path-dependent evolutionary pattern. As Manulak shows, however, it is possible to produce endogenous, non-incremental change out of a convergence of expectations at certain critical points. For this to happen, however, “temporal focal points” (TFPs) are needed to stimulate such convergence processes. Both the Stockholm (1972) and Rio (1992) conferences were such TFPs.

The question, then, is why some major international conferences have this quality of a TFP while others lack it. This is the analytical puzzle at the heart of the book’s empirical investigation. Manulak develops a carefully crafted causal model rooted in institutionalist theory to explain these different outcomes and tests this model with the help of a structured comparison of several major environmental conferences since the 1970s. The answer, in short, is that timing matters: “In order for change to occur, a large number of moving parts must come into alignment at one point in time” (p. 233). This is where political agency enters the picture. Political entrepreneurs—individuals such as Maurice Strong, who chaired both the Stockholm and Rio conferences—can make a difference by helping bring about the “crystallization of temporal coordination” (p. 249).

Manulak’s book is an excellent read. It is meticulously researched, and it offers a sophisticated revision of established institutional theories that should appeal to a wider IR audience. A particular strength is its extensive use of primary sources from archives that recently became available and cover the period until nearly the end of the twentieth century. This material will be of particular interest to those who would like to learn more about the role of international summits in the evolution of international environmental policy making. The field of GEP would benefit from more such efforts to combine theoretical innovation with deep historical research.

Charles Sabel’s and David Victor’s book, Fixing the Climate, is less of a historical account of international climate politics than a systematic effort to uncover the hidden lessons of experimentalist approaches in environmental governance. Although it opens with a review of what the authors describe as more than 30 years of misguided international climate negotiations, the book’s focus is on selected historical cases of policy experimentation, mainly at the national level. These cases are drawn from a wide range of environmental contexts. Four are domestic US cases: California’s efforts to reduce transport emissions by setting high standards for combustion engines; the Clean Air Act’s role in bringing down sulfur emissions; the Advanced Research Projects Agency’s (ARPA-E) contribution to clean energy innovation; and California’s efforts to integrate renewables into the electricity grid. Two additional cases are from Europe and Latin America: Ireland’s implementation of EU water-quality rules and Brazil’s efforts to reduce deforestation in the Amazonian region.

At first sight, the selection of case studies seems somewhat idiosyncratic, and it is not immediately clear how they add up to support the book’s overall intention of “fixing the climate.” Each case is about fairly limited achievements in reducing specific forms of industrial pollution or protecting ecosystems, yet other and arguably bigger challenges—for example, reducing coal consumption in emerging economies, cleaning up global shipping and aviation, and curbing the rise in global meat consumption—are not addressed in the book. But the point of the selected cases is to derive a theory of experimentalist governance (developed in chap. 3) that can then be applied to the panoply of policy interventions needed to curb the global warming trend.

Sabel’s and Victor’s approach yields interesting results. Starting with the reminder that climate change is characterized by a high degree of uncertainty, they dismiss top-down policy making and rigid implementation of internationally agreed targets. Instead, governments need to adopt an experimentalist mindset, which involves regulatory collaboration, flexibility, innovation, and learning. In this experimentalist approach, regulators “embrace uncertainty” and “invite doubt” (p. 60). They encourage deliberation that breaks down regulatory hierarchies, engages relevant experts, and establishes “feedback loops” through “peer review” (p. 65).

Despite its inherent open-endedness and flexibility, experimentalist governance still needs to be able to set firm parameters and impose sanctions to “break the grip of the status quo” (p. 67). When relevant actors obstruct environmental progress or refuse to participate in collaborative governance, their incentives may need to be changed through “penalty defaults.” Sabel and Victor identify three sources for such sanctions: organized “moral outrage,” as is the case with NGOs pressuring companies to improve their environmental performance; legal requirements imposed by regulators; and “asymmetries of power and economic position” that allow economically powerful actors to impose their standards on weaker ones (pp. 71–72). Thus, experimentalist governance combines both carrots and sticks to coax and corral polluting industries into a path of deep decarbonization.

To be sure, the argument for experimentation in climate governance is not entirely new (for example, the authors cite but do not engage with Matthew Hoffmann’s 2012 book on global climate experimentation). However, Sabel and Victor are able to derive their own distinctive approach. They are right to highlight the importance of regulators promoting “innovation at the technological frontier” while remaining agnostic about how this can be achieved. As their case studies show, there simply is no “right” strategy. Instead, a mix of approaches is needed: technology-forcing regulation, market-based instruments, and industrial policy “constitute the principal choices for climate change intervention” (p. 104). Furthermore, innovation-oriented regulation needs to be contextualized, adapted to local conditions of technical, social, and economic uncertainty and democratic decision making. As the discussion in chapter 5 shows, “even the biggest problems have to be solved close to the ground” (p. 150).

How does this model of experimentalist governance, rooted in sectoral innovation and regulatory localization, fit into the global response to global warming? After all, the authors’ ambition is to propose a new approach to international climate governance, one that “reorients our current climate change regime away from failed efforts based on ex ante global consensus, and toward a system anchored in local and sectoral experimentalism and learning” (p. 4). The Montreal Protocol of 1987 is presented as a model, especially its sectoral approach to phasing out ozone-depleting substances (ODS) and its promotion of collaborative problem solving as exemplified by its Technical Options Committees. Whereas other scholars have focused on the ozone regime’s firmness and the use of trade sanctions, Sabel and Victor draw our attention to the regime’s ability to engage relevant actors in a trial-and-error search for solutions to eliminating ODS.

The book contains many original insights, but the application of experimentalist thinking to the international level is less successful. For one, the attempt to juxtapose experimentation in the ozone regime with Kyoto Protocol-style rigidity in climate politics strikes me as problematic. We are told that “global commitments, achieved through diplomacy, should be the outcome of our efforts rather than the starting point” (p. 3). Yet, this is precisely how the Montreal Protocol negotiations managed to create a successful regime: they started out with internationally agreed targets and timetables for the ODS phase-out, which then set firm expectations for industrial innovation and regulatory experimentation. Moreover, the characterization of 30 years of “failed” UN climate diplomacy leads the authors to a somewhat confusing assessment of its latest result, the 2015 Paris Agreement. Initially introduced as “important but ultimately flawed” (p. 3), we later learn that Paris put an end to “Kyoto-style diplomacy,” introduced “an alternative order,” and established “the legitimacy and foci for climate action” (p. 169). By the end of the book, it becomes clear that the Paris Agreement is indeed much closer to the model the authors themselves advocate.

Despite these shortcomings, however, there can be little doubt that this book makes an original contribution to GEP scholarship and deserves to be widely read.