The legislative politics of climate change mitigation: Evidence from the European Parliament

On 4 November 2025, the European Studies Centre hosted Mihail Chiru, Associate Professor in Comparative Central and Eastern European Politics at the University of Oxford, for a seminar that placed the political economy of climate mitigation at the heart of contemporary parliamentary politics in Europe. Chaired by Othon Anastasakis, Director of the ESC, the seminar opened with a simple but powerful observation: mitigation policies typically impose concentrated, short-term costs while delivering diffuse, long-term benefits. This structural asymmetry, Chiru argued, makes climate policy especially vulnerable to politicisation. Against this backdrop, he asked whether mainstream parties in the European Parliament respond to electoral pressure from populist and radical-right (PRR) parties by moderating their support for ambitious climate legislation.

Chiru's empirical strategy exploits a distinctive institutional feature of the European Union. Because MEPs from across member states vote on the same European Commission proposals, roll-call votes in the Ninth European Parliament provide a rare opportunity to examine how domestic political conditions shape transnational legislative behaviour. Focusing on 94 salient mitigation votes across 19 policy files—including the EU Climate Law, ETS reform and vehicle emission standards—Chiru combines a roll-call dataset of around 42,000 observations with Chapel Hill Expert Survey measures of party positions, time-varying national polling to capture PRR strength, and eight semi-structured interviews with MEPs and parliamentary assistants working on ENVI and climate files.

Analytically, Chiru begins from established expectations about MEP voting: national party positions and European party-group coordination matter, but domestic electoral incentives may reinforce the political costs of decarbonisation. He tests the hypothesis that where PRR parties are stronger, mainstream MEPs will be less likely to support ambitious mitigation measures. To do so, he estimates a Bayesian multilevel binomial logit model that nests MEPs within national parties, electoral districts and European party groups, while allowing the effects of PRR support to vary over time at the district level.The results confirm the continuing importance of party-group politics. Greens and several left-aligned groups record the highest average levels of support for ambitious mitigation policies, while members of the EPP, Identity and Democracy (ID) and European Conservatives and Reformists (ECR) groups cluster substantially lower. Within party groups, economic left-right positioning also matters. Parties located further to the economic left proved less supportive of certain mitigation measures, suggesting that concerns over the distributive costs of decarbonisation can, in some cases, outweigh environmental objectives. Most importantly, Chiru found evidence that mainstream MEPs do accommodate PRR electoral pressure: as PRR popularity increases within a member state, the probability that mainstream legislators support ambitious mitigation measures declines. Although the substantive effect is moderate, it remains consistent across alternative model specifications and robustness checks.

The interview material adds important context to these quantitative findings. Conversations with MEPs and parliamentary assistants suggest that PRR politicisation is most influential where mainstream parties face direct electoral competition from the radical right, and less so among Greens and core left parties that retain strong pro-climate commitments. Interviewees also identified several factors contributing to legislative rollback: the decline of sustained pro-climate mobilisation following the peak of the Fridays for Future movement; external geopolitical shocks, particularly those affecting energy security; and partisan realignments that sometimes enable cooperation between mainstream and PRR actors, weakening legislative ambition.

The seminar also highlighted important qualifications. Not all mitigation policies impose the same domestic costs, and variation across policy areas may influence patterns of political accommodation. Lobbying, subnational variation and the institutional relationship between national parties and their MEPs further complicate causal inference, while the relatively weak direct electoral link between MEPs and voters means that national party organisations and European party-group discipline remain powerful mediating influences. During the discussion, Anastasakis raised questions about compliance and geography, asking how implementation varies across member states and whether energy shocks and geopolitical developments amplify or dampen PRR effects. Audience questions explored the role of agricultural emissions and farm lobbying, the measurement of PRR strength, electoral timing, and the interaction between European party groups and national parties.

Chiru concluded with a measured assessment. There is evidence that mainstream legislators accommodate electoral pressure from PRR parties, but the effect is moderate rather than transformative. Party-group politics, national political economy and country-level differences continue to explain much of the variation in MEP voting. Parliamentary support for ambitious climate mitigation may become more fragile where populist parties are electorally strong, but legislative outcomes cannot be reduced to PRR dynamics alone. The seminar therefore underscored the value of combining large-N legislative analysis with qualitative fieldwork to uncover the micro-mechanisms linking voter preferences, party strategy and institutional incentives.

Overall, the seminar offered a careful and methodologically sophisticated contribution to the study of climate politics and legislative accommodation in Europe. By combining roll-call data, expert surveys and qualitative interviews, Chiru demonstrated how domestic populist pressures can shape legislative behaviour in a transnational parliament while highlighting the enduring importance of institutions and party organisation in mediating those effects.

By Yangyang Zhao (Events Assistant)