Change in Carbon Dioxide Emissions in Japan:The Synthetic Control Method

Japan is a developed country dedicated to complying with agreements for mitigating hazardous gases causing global warming. However, the 2011 Great East Japan Earthquake (hereinafter referred to as the natural disaster) that occurred in March 2011 created a situation that the country had to amend the environmental policy related to climate change. This study employed the synthetic control method (SCM) to estimate the impact of a natural disaster on carbon dioxide (CO2) emissions. The outcome variable is CO2 emissions from electricity generation index (2000=100) and the intervention window is 1995-2020 (pre-intervention:1995-2010 and post-intervention:2011-2020). Analyses of 34 countries in OECD and UNFCCC and placebo studies were performed using leave-one-out tests, and post- to pre-mean squared prediction error (MSPE) ratios to evaluate the statistical inferences. The results indicated a meaningful relationship between the natural disaster and an increase in CO2 emissions. Unlike the situation of countries in the control group, Japan showed a significant increase in CO2 emissions after the natural disaster.