The Adoption of State Climate Change Policies and Renewable Portfolio Standards: Regional Diffusion or Internal Determinants?

This paper draws upon policy innovation literature and quantitatively explains the adoption of state climate change policies, leading to a broader question-what makes states more likely to adopt policies that provide a global public good? First, existing empirical evidence relating to state climate change policy adoption is reviewed. Following this brief discussion, several analytic approaches are presented that test specific hypotheses derived from the internal determinants and regional diffusion models of policy adoption. Policy diffusion is tested as a function of the motivations, resources, and obstacles of policy change. Motivations for policy innovation include environmental conditions and demands of citizens. Resources include state financial and geographic resources, such as wind and solar potential. Obstacles include a state's reliance on carbon-intensive industries such as coal and natural gas. The results show that internal factors, particularly citizens' demands, are stronger predictors of states' policies than are diffusion effects from neighboring states.