Loïc Berger

Understanding the drivers of public support for climate policies is crucial for designing socially feasible policy packages. However, most large-scale public opinion surveys focus primarily on mitigation policies. Here, we combine two representative survey waves from nine European countries (n = 27,910) to directly compare determinants of public support for climate change mitigation versus adaptation measures. We find that respondents support both mitigation and adaptation as policy objectives, but support specific adaptation policies slightly more than specific mitigation measures. Moreover, support for the two is shaped by a different composition of individual characteristics and policy evaluations. While adaptation support is driven primarily by perceived effectiveness, mitigation support is mostly driven by cost salience and politicisation. Our results suggest a stark difference in how Europeans incorporate the costs and benefits of mitigation versus adaptation policies into their support, and suggest avenues for remedying this imbalance.

While models used to evaluate climate change are inherently simplified, and thus imperfect, representations of reality, they remain indispensable tools for quantifying policy impacts and guiding decision-making. How can we leverage these models while accounting for their potential misspecification -the possibility that none of the existing models is adequate? This paper addresses this question by applying recent advances in decision theory to analyze how concerns about model misspecification influence key climate strategies, including the stringency of emissions targets and the extent of climate overshoot. Using a decision-theoretic framework applied to emulators of IPCC-assessed scenarios, we quantify the trade-offs between mitigation costs and climate-induced economic damages. We show that when decision-makers explicitly account for the possibility of model misspecification, they rationally adopt more ambitious climate goals, characterized by stricter carbon budgets and reduced reliance on emissions overshoot. These results underscore the importance of integrating model misspecification concerns into climate policy design, providing a rigorous foundation for precautionary and robust decision-making under deep uncertainty.

The feasibility of implementing climate policies relies on citizen support. While recent efforts have focused on shifting the attitudes of policy opponents, little is known about the middle group who neither reflexively endorse nor reject mitigation measures. Here, using a survey of climate policy preferences across 13 EU countries (n = 19,328) in 2024, we identify the ‘conditionals’—a crucial faction of moderates whose support shifts across 15 climate measures— and examine the factors influencing their choices and quantify their electoral impact. Conditionals constitute 33% of Europeans who are active voters for the dominant centrist and centre-right parties. The preferences of conditionals hinge upon specific policy instruments and the perceived cost–benefit balances but less on fixed ideology or demographics. The potential shift of conditionals plays a vital role in shaping overall patterns of public policy support and electoral outcomes. Our findings emphasize the visible benefits of strategic engagement with conditionals for climate policy success.

The European Union (EU) has adopted ambitious climate policies to reduce greenhouse gas emissions by 55% by 2030. While technical, economic, and political feasibility have been widely analyzed, far less is known about a critical enabling factor: whether key societal actors perceive these targets as credible and achievable. In this study, we elicit probabilistic beliefs about future EU emission reductions from a sample of citizens designed to be representative across 12 EU member states and compare them with the expectations of climate policymakers and experts. Our findings reveal that all three groups anticipate substantial progress compared to current levels. At the same time, citizens are more skeptical about achieving the target and substantially more uncertain than elites, expecting, on average, a 43% reduction by 2030 compared to the EU’s 55% reference. Moreover, we identify a notable misalignment: elites tend to systematically underestimate public skepticism. This gap underscores the need to improve policy communication, directly address citizens’ concerns, and foster a shared understanding to enhance the perceived credibility and political sustainability of the EU’s climate goals.

We report the results of two experiments designed to better understand the mechanisms driving decision making under ambiguity. We elicit individual preferences over different sources of uncertainty, entailing different degrees of complexity, from subjects with different sophistication levels. We show that (1) ambiguity aversion is robust to sophistication, but the strong relationship previously reported between attitudes toward ambiguity and compound risk is not and (2) Ellsberg ambiguity attitude can be partly explained by attitudes toward complexity for less sophisticated subjects only. Overall, regardless of the subject’s sophistication level, the main driver of Ellsberg ambiguity attitude is a specific treatment of unknown probabilities.

The feasibility of implementing climate policies relies on citizen support. While recent efforts have focused on shifting the attitudes of policy opponents, little is known about the middle group who neither reflexively endorse nor reject mitigation measures. Using a survey of climate policy preferences across 13 EU countries (n=19,328) in 2024, we identify the ‘Conditionals’- a crucial faction of moderates whose support shifts across 15 climate measures, examine the factors influencing their choices and quantify their electoral impact. Conditionals constitute 33% of Europeans who are active voters for the dominant centrist and centre-right parties. Conditionals’ preferences hinge upon specific policy instruments and the perceived cost–benefit balances, but less on fixed ideology or demographics. The potential shift of Conditionals plays a vital role in shaping overall patterns of public policy support and electoral outcomes. Our findings emphasize the visible benefits of strategic engagement with conditionals for climate policy success.

The European Union (EU) has adopted ambitious climate policies aimed at reducing greenhouse gas emissions by 55% by 2030. While technical, economic, and political feasibility have been widely analyzed, far less is known about a critical enabling factor: whether key societal actors perceive these targets as credible and achievable. Though often correlated with support, beliefs about a policy's effectiveness reflect a different underlying judgment and call for different elicitation methods. In this study, we elicit probabilistic beliefs about future EU emission reductions from a representative sample of citizens across 12 EU member states and compare them with the expectations of climate policymakers and experts. Our findings reveal that, while policymakers and experts are relatively optimistic, the general public is more skeptical, expecting, on average, a 43% reduction by 2030 compared to the EU's 55% target, and expresses substantially greater uncertainty. Moreover, we identify a notable misalignment: stakeholders systematically overestimate public optimism and confidence. These gaps highlight the importance of improving policy communication, addressing public skepticism, and fostering shared understanding to enhance the perceived credibility and political sustainability of the EU's climate goals.

We investigate the validity of a double random incentive system where only a subset of subjects is paid for one of their choices. By focusing on individual decision-making under risk and ambiguity, we show that using either a standard random incentive system, where all subjects are paid, or a double random system, where only 10% of subjects are paid, yields similar preference elicitation results. These findings suggest that adopting a double random incentive system could significantly reduce experimental costs and logistic efforts, thereby facilitating the exploration of individual decision-making in larger-scale and higher-stakes experiments.