Do political leaders affect the climate mitigation of the nation they govern, and if yes, to which leader characteristics voters who care about climate should pay attention to when they vote? There is abundant literature on how ideology of political parties in power affects climate policy outcomes, but there is nothing similar for individual characteristics of government leaders. This is the first study of its kind, building on a dataset of government leaders of OECD countries for the period 1992-2017. We find that leaders’ professional background is the trait that has the strongest effect. Higher emissions and lower renewable energy deployment are more likely during the tenure of former businesspersons or economists. Teachers and doctors instead are associated with lower emissions and with higher rates of renewable energy deployment. Our results suggest that voters and pressure groups should care about candidates’ professional background, in addition to their party’s ideology.