Their assumptions about climate being controversial are empirically disproven -- a GND is politically feasible only when ambitious.

A second hurdle is the fact that many politicians tend to focus on avoiding public blame and reducing the political risks of costly but effective mitigation. Decision-makers often believe that citizens are not willing to pay the price for effective mitigation (Hertel-Fernandez et al. 2019). What is more, many citizens seem to have similar beliefs, and perceive other members of society to be unsupportive of investment into effective mitigation (Mildenberger and Tingley 2017). Political polarization, distrust in science, and populism are on the rise and some people have raised serious doubts about the scientific consensus concerning the severity of climate change and human responsibility for it (Huber et al. 2020). Despite this, the last few years have shown that politicians do not necessarily need to be overly concerned about public backlash against ambitious climate mitigation. Green parties around the world have gained political momentum and recent survey research shows that in countries that are major economic actors like the USA, China, India, Germany, South Africa, and the United Kingdom – a majority of citizens support climate policies with perceptible mitigation costs, for example, policies that significantly increase the price of emission-intensive goods like fossil fuels or meat products (Beiser-McGrath and Bernauer 2019, Fesenfeld et al. 2020, Wicki et al. 2019). These survey results are buttressed by real-world election outcomes.3 Several policy recommendations can be derived from this: First, to generate public support, policymakers should not hide policy costs but communicate to citizens that they are taking their interests seriously, designing policies in a socially fair way, and should explain to people the rationale for adopting ambitious climate policies by creating a “positive climate policy narrative” (Fesenfeld et al. 2021). Second, policymakers should propose effective and feasible climate policy packages that bundle ambitious mitigation measures with policies that compensate mitigation costs for citizens by including clear benefits forthem, and increase the perceived fairness of such policies (Fesenfeld et al. 2020, Wicki et al. 2019). Credible consideration of fairness principles in policy design can effectively reduce the risks of public backlash (Klenert et al. 2018, Beiser-McGrath and Bernauer 2019).4 Bundling social, economic, and climate policies into GND packages that foster job growth in cleaner industries (e.g., the renewable energy industry), increasing social security, and fostering mitigation efforts can help to build broad public support and the popularity of the former among politicians – especially during the COVID-19 crisis (Bergquist et al. 2020). Low interest rates and increasing revenues from carbon taxation also provide governments with the unique opportunity to finance such ambitious GND packages. Third, particularly in the USA, the experience of extreme political polarization and populism is likely to have altered the belief of leading politicians and lobbyists that the cost of political instability is larger than the cost of introducing a GND. While distrust of the scientific consensus about climate change, populism, and political polarization can be hurdles to effective mitigation, in most countries around the world the vast majority of citizens believe in the reality of human-caused climate change (Steg 2018). In essence, policymakers can credibly communicate they are acting in the interest of citizens when they adopt an ambitious GND (Huber et al. 2020, Fesenfeld et al. 2021) The third key hurdle is that powerful incumbent industries show little interest in bearing the cost of mitigation if it is associated with uncertain benefits for themselves. Collective action theory predicts that strong lobby groups of fossil fuel and other pollutant industries prevent effective mitigation because of their ho mogenous interests and significant conflict capacity (for example, Bernauer 2013). However, while I do not contest the basic premises of collective action theory, I argue that its implications for climate policymaking have to be reconsidered. Although powerful incumbent industries, like the meat and coal industry, have long been wellorganized opponents of ambitious climate policy, the situation for at least some of those players has changed dramatically. Not only are powerful industries recognizing the short-term costs and benefits of mitigation, but they also have an increasingly diversified portfolio of products, including clean technologies, to deploy5 . Portfolio diversification lessens companies’ inclination to engage in conflict in relation to lobbying against ambitious climate policies. In fact, portfolio diversification leads to ambiguous lobbying strategies. In this sense, the predictions made by collective action theory can work in favor of a GND. International competition from new market players like Tesla in the automotive industry or Beyond Meat in the food industry are increasingly changing the odds in favor of incumbent actors supporting ambitious climate policies pear unfair, yet realistically, in light of the enormous social cost of a further delay in effective mitigation, but the good news is that both the public and front-running green industry players are willing to bear some transition costs and to compensate losers (Fesenfeld et al. 2020, Wicki et al. 2019, Rinscheid and Wüstenhagen 2019, Beiser-McGrath and Bernauer 2019). Free-riding risks The fourth hurdle to ambitious climate policies, which receives prominent attention in social science literature, is based on global public goods theory. This theory forecasts that successful international cooperation for mitigation is difficult to achieve, given that actors have the incentive to free-ride on the mitigation efforts of others (Nordhaus 2015, Bernauer 2013). However, empirical evidence for this argument is contested and indicates that it is domestic distributional conflict rather than international free-riding concerns that determine national climate policy ambitions (Aklin and Mildenberger 2020). Local and national climate mitigation co-benefits and increasing positive returns from climate mitigation might also reduce the free-rider problem (Hale 2020). Moreover, the “climate club” literature