Partisanship is one of the largest and most studied social barriers to climate change mitigation in the United States. Here we expand conceptualizations of 'left-right' or 'Republican-Democrat' towards understanding partisanship as a multidimensional social identity with both negative and positive elements. Partisan support or opposition for climate action can be driven by identification with the partisan in-group (positive or 'expressive' partisanship), as well as perceived threats from the 'out-group' (negative partisanship). Using survey data, we show when negative and expressive partisanship is low, climate policy support is similar for Republicans and Democrats. But differences in policy support increases when partisan identification amplifies. Yet, for climate behaviors, we find more limited partisan effects. The proposed multidimensional partisanship framework sheds light into the role of partisan polarization in shaping climate change action and points to alternative ways to transcend partisan barriers to climate action.