To confront the climate crisis, we need political change involving a dramatic shift in domestic and transnational norms. Norm models should be recognized as one of the theoretical tools within the panoply of approaches to examine and address climate change. The most promising norm campaigns underway are those that target fossil fuel companies and government policies that support them (e.g., subsidies).

In response to the sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC), United Nations Secretary-General Antonio Guterres spoke of the need to “massively fast track” climate efforts (UN/Guterres 2023). Such a massive fast track requires changes in energy policy and technology as well as a dramatic shift in domestic and transnational norms. Despite several useful and important articles on this topic (Allan Reference Allan2017; Blondeel, Colgan, and Van de Graaf Reference Blondeel, Colgan and Van de Graaf2019; Busby and Urpelainen Reference Busby and Urpelainen2020; Green Reference Green2018a, Reference Green2018b; Mitchell and Carpenter Reference Mitchell and Carpenter2019), international relations (IR) norm theory has not yet been well incorporated into the literature on climate change. Economists, political scientists, and science researchers mainly address the politics of climate change using a rationalist or consequentialist approach that focuses on cost–benefit analysis and getting the incentives right through either carbon pricing or institutional design (Blondeel, Colgan, and Van de Graaf Reference Blondeel, Colgan and Van de Graaf2019). IR scholars have modeled the politics of climate change as a collective-action problem with perverse incentives. These are important and necessary approaches, but they do not take beliefs seriously and do not consider the possibility that norm changes could matter for the solution.

Theories of norm change can add to our understanding when combined with the material factors that have long been at the forefront of climate research. Green (Reference Green2018a, 104) argued that the potential role of global moral norms for climate governance has been ignored, providing as evidence that norms are not covered in either the “International Cooperation” chapter of the IPCC’s Working Group III Report or the Research Handbook on Climate Governance.

Climate science has reached a clear picture of the causes and processes of climate change but has been less successful in defining political solutions. This is why norms—that is, shared understandings about appropriate behavior—are important: a norms cascade could provide the impetus necessary for the politics of global change. Norms also can become part of state and subnational identities, which in turn influence behavior. This has happened at the subnational level in US states such as California and at the national level in some European countries, where many conservative parties and even some far-right populist parties express support for pro-climate policies (Batstrand Reference Batstrand2015; Hess and Renner Reference Hess and Renner2019). State and substate actors with pro-climate identities are more willing to make early costly subsidies to develop sustainable energy technologies, as Germany and California have done in the area of solar power. Norms and identities informed by these norms thus explain why some policy makers take costly action and how the very idea of what is rational is changed by the beliefs of some actors. For example, given European pro-climate identities, it is now “rational” for European right-wing parties to not challenge pro-climate policies.

When norm change is successful, it follows a characteristic pattern that Finnemore and Sikkink (Reference Finnemore and Sikkink1998) called a norm life cycle, starting with norm emergence led by norm entrepreneurs, followed by norm diffusion, and sometimes to a “norm bandwagon” and a norm cascade (Sunstein Reference Sunstein1996). The norm-emergence period depends on highly motivated norm entrepreneurs who persuasively frame issues, organize coalitions, and get issues on the global-governance agenda. They benefit from organizational platforms from which to launch their campaigns. Norm emergence and diffusion often is a long, slow process. However, if it is successful, it may be followed by a norm cascade, which can happen more quickly. We see these patterns historically in issues including women’s suffrage (Finnemore and Sikkink Reference Finnemore and Sikkink1998), antislavery and the birth and expansion of international human rights (Keck and Sikkink Reference Keck and Sikkink1998), and the move to individual criminal accountability for mass atrocity (Sikkink Reference Sikkink2011). We also have seen norm cascades with simpler but important issues involving seatbelts and smoking behavior. These two campaigns involved changing notions of what was natural, possible, and appropriate. Two relatively recent perceived existential global threats have been attenuated by norm changes: the threat of nuclear annihilation and the possibility of the “population bomb” leading to famine and mass starvation (Ehrlich Reference Ehrlich1968). Neither of these possible scenarios has disappeared, but we hear less about them today as existential threats. Norm changes played a role in each issue: the norm of a “nuclear taboo” increasingly made first use less likely (Tannenwald Reference Tannenwald2007), and norms about women’s empowerment involving women imagining alternatives to having large families decreased the perceived threat posed by the “population bomb” (La Ferrara, Chong, and Duryea Reference Ferrara, Eliana and Duryea2012). I argue that anti–fossil fuel norms (AFFN) provide the most promising candidates for a norms cascade and, within AFFN, anti-coal norms already may be initiating cascade effects, for both ideational and material reasons. International anti-coal campaigns, such as the Powering Past Coal Alliance, have adopted norms and have been successful in convincing international financial institutions to end their support for coal plants—even though many countries continue to build them domestically (Blondeel, Van de Graaf, and Haesebrouck Reference Blondeel, Van de Graaf and Haesebrouck2020).

I advocate for attention to norms and norm theory and not simply “bringing ethics back in” to the climate change debate (Mitchell and Carpenter Reference Mitchell and Carpenter2019). Norms involve ethical issues about “appropriate behavior” and thus right and wrong. However, social science has wide support for the existence and power of norms in many realms of human behavior, including economics (La Ferrara, Chong, and Duryea Reference Ferrara, Eliana and Duryea2012), which goes well beyond the idea of being ethical. A norm cascade is related to threshold models, which involve different dynamics than the rationalist model of change mainly used in climate change research. This different dynamic is well grounded in psychological literature on the dual-processing brain because threshold decision making involves more intuitive and emotional “System 1” or “thinking fast” cognition (Kahneman Reference Kahneman2011; Price and Sikkink Reference Price and Sikkink2021). We know that emotion and intuition influence debates about climate—especially among young people, whose sense of existential despair often is palpable. Yet, even as climate economists and scientists recognize that such “apocalyptic grief” is happening, with a few exceptions, their theoretical solutions do not incorporate the relevance of possible ideational effects (Becht, Pajuste, and Toniolo Reference Becht, Pajuste and Toniolo2023). If such grief among young people is accompanied by their embrace of major norm shifts about consumption and reproduction—a process that appears to be underway in the developed world—it could contribute to a norm cascade.

Threshold models of collective behavior involve “complex contagion—when group members look around to see what others are doing before deciding to join in” (Granovetter Reference Granovetter1978; Macy and Evtushenko Reference Macy and Evtushenko2020). Norm theorists still do not have a fully persuasive explanation of the conditions under which norm cascades occur. However, we know that most global cascades are fast in world time but involve long struggles over decades: antislavery campaigns took more than 100 years and women’s suffrage took 50 years—that is, if we measure from the first groups who advocated new norms to the great majority of countries that abolished slavery and gave women the vote. A threshold model needs a critical mass of instigators to jump-start collective action (Macy and Evtushenko Reference Macy and Evtushenko2020).

Busby and Urpelainen (Reference Busby and Urpelainen2020) adapted a norms-cascade model to climate, calling for a “participation cascade,” in which decarbonization is “quickly adopted by a critical mass of actors responsible for a significant share of emissions in a sector or issue space.” However, the critical mass does not have to be the majority of people in any country, and even “costly” moral action is possible under certain conditions. The so-called Saints group in the British government in the early-nineteenth century made antislavery a condition of their membership in the governing coalition, producing what Kaufmann and Pape (Reference Kaufmann and Pape1999) called the “saintly log-roll” that led Britain to abolish slavery and use its navy to enforce abolition on other countries. The saintly log-roll was “rational” for coalition partners, but the log-roll is driven by the strong beliefs of the norm entrepreneurs—in this case, the Saints. There is a parallel process in modern-day climate politics in which the commitment of a minority Green Party also can lead to costly changes in national policy.

There has been and will continue to be uneven acceptance of, for example, AFFN across countries and regions (Green Reference Green2018a). This is partly related to state identities, as discussed previously but also to the nature of political systems. In some institutional situations, a strongly motivated minority can be sufficient to pass anti–fossil fuel bans (Green Reference Green2018b). Countries with proportional representation systems appear to be more able to adopt costly climate policies because these rules increase electoral safety, allowing politicians to impose short-term costs on voters (Finnegan Reference Finnegan2022).

The world has passed through the policy cycle on climate change from framing to agenda setting to multiple waves of public standard setting through a range of treaties. Scholars now realize that the Kyoto Protocol was flawed and that the more-promising Paris Agreement governs future action. However, as Keohane and Oppenheimer (Reference Keohane and Oppenheimer2016) stated, “The Paris Agreement accomplishes little—but it opens what was a locked door. That door is now a little bit ajar—pushing hard could carry us through it to a better outcome, but nothing will be accomplished at the international negotiation level alone.” From a norms-theory perspective, I consider this to mean that the institutional features are in place to facilitate climate action but that the powerful societal impetus for change is missing (Coglianese Reference Coglianese2020). A concerted AFFN campaign could provide this necessary impetus.

Environmental advocacy has increased dramatically. The literature suggests that the presence and power of climate advocates contribute to emissions reductions; however, pro-climate groups are vastly outnumbered by well-organized, well-funded interest groups working in support of fossil fuels—or at least the energy status quo (Trachtman and Meckling Reference Trachtman and Meckling2022). Mass mobilization on climate, at least in the United States, is a relatively new phenomenon still in its early stages (Fisher and Nasrin Reference Fisher and Nasrin2021; Trachtman and Meckling Reference Trachtman and Meckling2022). Early civil-society activism on climate change primarily used a science-based frame, and it was not until the 2007–2009 period that approaches to climate justice began to appear (Hadden Reference Hadden2015).

Environmental networks have not agreed on which types of climate norms should take precedence. Climate-justice movements succeeded in introducing justice issues into the debate (Hadden Reference Hadden2015), but their agenda is diverse and at times contradictory. Some justice advocates believe that justice will not be achieved until capitalism has ended—a position that is unlikely to mobilize a far-reaching coalition capable of generating a norm cascade. Green (Reference Green2018a) proposed persuasively that AFFN are the most promising climate norms. It is not necessary to end capitalism to address climate change, but it may be necessary to delegitimize and even prohibit certain types of fuels and the companies that produce them. Changes in social norms about consumption that underpin our current model of production also are necessary (Hadden Reference Hadden2020).

A norm cascade must involve a much broader range of actors in addition to social movements and transnational networks, including states, subnational actors, international organizations, and private actors. The motives are not only material costs and benefits but also questions of legitimacy, reputation, and esteem; the dominant mechanisms are socialization, institutionalization, and emulation (Finnemore and Sikkink Reference Finnemore and Sikkink1998). But why have the politics of norm change not yet been strong enough to supercharge a norm cascade capable of keeping up with climate change itself? Some insights from the norm literature are relevant. Norm theory hypothesizes that issue characteristics matter, and issues that involve bodily harm to vulnerable populations are the types of issues that often have cascaded in the past (Keck and Sikkink Reference Keck and Sikkink1998). Climate change involves the potential of bodily harm to vulnerable populations; however, until recently, this harm was regarded as something that would happen in the distant future. As extreme weather events are now creating bodily harm in the present, this part of norm theory may instigate a more rapid response. There is evidence that personally experiencing extreme weather conditions can lead individuals to have greater concern about climate, support for pro-climate policies, and—in some cases—support for Green political parties (Garside and Zhai Reference Garside and Zhai2022). Because of the importance of real-time bodily harm to fuel a norm cascade, activists also should stress the human health pollutants associated with the sourcing, production, and burning of fossil fuels—especially on vulnerable populations, including children. Keck and Sikkink (Reference Keck and Sikkink1998, 27) argued that advocacy networks are more effective if they can frame problems as being caused by deliberate (i.e., intentional) actions of identifiable individuals. However, climate change is perceived as such a complex structural problem that is has been difficult to target specific actors. AFFN meet this criterion because they frame fossil fuel companies as intentional actors who can be targeted.

A second insight is that norm campaigns succeed “when the actions they prescribe are framed as a solution to salient problems that potential adopters face” (Blondeel, Colgan, and Van de Graaf Reference Blondeel, Colgan and Van de Graaf2019). Blondeel, Colgan, and Van de Graaf (Reference Blondeel, Colgan and Van de Graaf2019) argued that AFFN have been most successful when they are aimed at reducing environmentally harmful fossil fuel subsidies because this is linked to the salient problem of fiscal stability. Actors sometimes disagree on finding a common norm campaign because the impact of diverse climate policies often have a negative effect on the most vulnerable communities (Dolšak and Prakash Reference Dolšak and Prakash2022).

A third insight from norm theory is that simply finding an intentional target is not sufficient. The success of transnational advocacy networks will be greater when they face targets that are morally or materially vulnerable. Yet, fossil fuel corporations and the most powerful states that are resisting change (e.g., the United States, China, and India) have not yet proven vulnerable. Powerful actors with economic interests are doing everything possible to protect those interests. Fossil fuel companies worked hard to put forward counter norms, thereby sowing doubt about science and deflecting activism away from a focus on AFFN. The challenge for any AFFN campaign is to find ways to make these powerful actors more responsive, perhaps by focusing first on getting states to reduce fossil fuel subsidies.

Another problem comes from inside the climate coalition itself. The NGOs mainly involved in climate policy are still mainly professionalized epistemic communities driven by shared causal ideas and science (Hadden Reference Hadden2015; Mitchell and Carpenter Reference Mitchell and Carpenter2019). Some of these epistemic communities are dismissive of AFFN campaigns such as divestment, anti-coal campaigns, and other fossil fuel bans because they believe that they are not effective and distract from the correct solution to the climate problem—mainly carbon pricing. An early focus on reducing fossil fuel subsidies could bridge these divisions as well as highlight evidence that divestment pledges that go viral can impact stock values (Becht, Pajuste, and Toniolo Reference Becht, Pajuste and Toniolo2023).

If we nest the struggle for climate norms within other political processes to combine material and ideational factors, this can enhance the possibility of a climate norm cascade. Colgan, Green, and Hale (Reference Colgan, Green and Hale2021) proposed a dynamic model of asset revaluation based on a contest between owners of assets that accelerate climate change (e.g., fossil fuel companies) and owners of assets vulnerable to climate change (e.g., companies that insure coastal property). Colgan, Green, and Hale recognize that the missing piece of their analysis is the role of ideational factors, identity politics, and emotion—issues at the center of the norms-cascade model. They believe that their model “serves as a materialist conceptual scaffolding upon which scholars can add ideational variables to explain climate politics” (Colgan, Green, and Hale Reference Colgan, Green and Hale2021, 605). The norm-cascade model suggests how ideational variables can interact with this material scaffolding. Colgan, Green, and Hale (Reference Colgan, Green and Hale2021) pointed out that their theory is dynamic because, over time, “actors’ interests, power, and their willingness to mobilize will change with the valuation of their assets.” The norm-cascade model offers a broader version of this: over time, actors’ interests, power, and their willingness to mobilize will change, not only in relation to the valuation of their assets but also because they come to believe in new AFFN. It is the combination of these material and ideational changes that could propel a more rapid cascade in behavior.