Green party vote shares and public support for climate policy

Green party vote shares are often used to assess public support for climate policy. Yet in multiparty systems, votes may reflect strategic considerations as well as environmental preferences. This paper develops a decision-theoretic model showing how climate-minded voters may support a center-left party rather than a Green party when doing so increases the likelihood of defeating an anti-climate right. The model shows that Green party vote shares become a weaker indicator of climate demand when Green and center-left climate platforms converge, allowing voters to coordinate around a more viable alternative. I examine these implications using panel data from the Netherlands. Consistent with the theory, Green voters were more likely to switch to Labour and left parties than to the right, and Green support declined as Green and Labour climate positions converged. The findings suggest electoral competition can weaken the relationship between Green vote shares and support for climate policy.