CO2 emissions converge in the 50 U.S. states — Sequential panel selection method

This study applies the sequential panel selection method (SPSM) procedure proposed by Chortareas and Kapetanios (2009) to investigate the time-series properties of CO2 emissions for 50 U.S. states during the 1990 to 2010 period. SPSM classifies the whole panel into a group of stationary series and a group of non-stationary series. In doing so, we could clearly identify how many and which series in the panel are stationary processes. Empirical results from the SPSM using the panel KSS unit root test (Ucar and Omay, 2009) with a Fourier function, indicate that CO2 emissions only converge in 12 out of the 50 U.S. states in our analysis.