Do CO2 emission levels converge among 21 OECD countries? New evidence from unit root structural break tests

This study empirically re-investigated whether carbon dioxide (CO2) emissions series were stationary in 21 OECD countries during the 1960-2000 period. A suite of test statistics were employed, proposed by Sen (2003), with a model that simultaneously allows for a break within the context of Perron's (1989) mixed intercept and slope (Model C). The distinction between this study and previous ones lies in its control for breaks. Compared with the results from traditional unit root tests, the empirical findings provide further evidence that relative per capita CO2 emissions were stationary and were stochastically converging. In addition, structural breaks are identified in each country, and some important policy implications emerge from the results.