Have Greenhouse Gas Emissions from US Energy Production Peaked? State Level Evidence from Six Subsectors

Abstract

Analyses of the Environmental Kuznet's Curve (EKC) hypothesis have largely focused on economy level data with occasional analyses exploring sector level data. This paper exploits a new data set which contains sector level data on greenhouse gas emissions from the US energy sector as well as subsector data from six disjoint subsectors which together comprise the entire energy sector. The data contained in this data set is annual data at the state level from 1990 through 2011. A battery of EKC models are tested and some evidence supporting the EKC hypothesis is found for the US energy sector and its subsectors. We find that aggregated subsector level estimates outperform sector level estimate on in-sample accuracy. These estimated models are then used to forecast emissions for the energy sector. We find that EKC estimations for the energy sector as a whole are consistently lower than aggregated subsector EKC estimates. Addressing the title, we find limited evidence at best that US greenhouse gas emissions are at or near a peak.