University of California Institute on Global Conflict and Cooperation

Climate shocks are becoming more frequent and costly, yet their consequences for electoral competition remain contested. Existing work has focused primarily on whether climate shocks redirect support toward green parties by raising the salience of climate policy. We argue that climate shocks shape political party competition primarily by shaping voters' retrospective evaluations of government performance. Political trust determines how voters interpret that signal. Where trust in institutions is low, hardship confirms preexisting perceptions of elite neglect: incumbents lose votes and populist challengers, particularly on the radical right, gain support by framing disaster as evidence of institutional betrayal. Where trust is high, voters extend goodwill to incumbents navigating difficult circumstances, leaving support largely unaffected. We test these claims using subnational monthly data on party vote shares, political trust, and exogenous heatwave and drought events across 230 regions in 24 European countries between 1996 and 2020. Incumbent losses in low-trust regions reach ten percentage points after heatwaves and sixteen after extreme dry spells; populist gains reach five and twelve points respectively. We find only weak and inconsistent evidence of shifts toward green parties, suggesting that the dominant political dynamic following climate shocks is driven by institutional grievance rather than climate issue salience.