Does a Carbon Tax Reduce CO2 Emissions? Evidence from British Columbia
利用双重差分、合成控制和新提出的断点检测方法，评估北美首个主要碳税的效果，发现碳税减少了交通排放但尚未显著降低总二氧化碳排放，且现有碳税价格可能过低而难以在短期内见效。
Abstract Using difference-in-differences, synthetic control, and introducing a new break-detection approach, I show that the introduction of North America’s first major carbon tax has reduced transportation emissions but not ‘yet’ led to large statistically significant reductions in aggregate CO 2 emissions. Proposing a new method to assess policy based on breaks in difference-in-differences using machine learning, I demonstrate that neither carbon pricing nor trading schemes in other provinces are detected as large and statistically significant interventions. Instead, closures and efficiency-improvements in emission-intense industries in untaxed provinces have reduced emissions. Overall, the results show that existing carbon taxes (and prices) are likely too low to be effective in the time frame since their introduction.