Carbon emission policy in the United States: State patchwork vs. national policy

The lack of a national law in the United States to mitigate climate change has prompted many states and cities to take the lead in implementing policies to reduce their carbon emissions and adapt to the threats posed by a warming planet. This project adopts two established systems that classify states by their relative involvement in climate policy (Wheeler 2010; Lutsey et al. 2008) and combines them into a single, six-point ranking scale. States are then cross-tabulated against EPA data showing the amount and trajectory of each state's carbon emissions from the electrical power sector over the period 2005-2010. States with unexpected results---i.e. states with high climate policy scores but whose emissions surprisingly increased, and states with low climate policy scores but whose emissions surprisingly decreased---are selected as case studies and analyzed further. The project identifies specific factors such as changes in the use of coal or biomass to generate electricity, membership in regional cap-and-trade programs, local environmental conservation laws, and economic downturn that are critical---but not exclusive---to determining whether a state's emissions will rise or fall. The findings show the U.S. has a patchwork of climate policies with varying abilities to cut emissions. States often function as "policy laboratories" for implementing new regulations that might serve as models for federal action (Pew 2005). The project concludes that a single, unified national policy to transition the power sector from coal and natural gas to renewable energy---either through a carbon tax or EPA regulations on power plants---would more efficiently cut emissions than the current hodgepodge of state policies.