Diffusion Channels in Climate Change Adaptation Policy: Multipliers or Substitutes?

Policy diffusion occurs through multiple channels and mechanisms. However, our knowledge of interaction effects between these channels, such as noninstitutionalized exchanges, networks and higher-level funding, is limited. Although research generally suggests that reinforcing and substituting effects can emerge between these channels, they have yet to be conceptualized and studied in detail. This paper contributes to filling this gap. Focusing on local climate change adaptation policy in the centrally located German state of Hesse, it studies interaction effects between six soft policy diffusion channels: autonomous, collaborative, exemplary, persuasive, organized, and funded diffusion. The results show that autonomous exchanges become less important in driving adaptation policy development as municipalities join formal climate networks. Furthermore, network membership can amplify the positive effects of federal funding for adaptation. This paper improves our understanding of policy diffusion processes and provides policymakers with suggestions to accelerate local adaptation policymaking