Reduction in greenhouse gas emissions from national climate legislation

The international response to climate change has been inadequate, but not zero. There are 1,800 climate change laws worldwide. We use panel data on legislative activity in 133 countries over the period 1999–2016 to identify statistically the short-term and long-term impact of climate legislation. Each new law reduces annual carbon dioxide (CO2) emissions per unit of gross domestic product by 0.78% nationally in the short term (during the first three years) and by 1.79% in the long term (beyond three years). The results are driven by parliamentary acts and by countries with a strong rule of law. In 2016, current climate laws were associated with an annual reduction in global CO2 emissions of 5.9 GtCO2, more than the US CO2 output that year. Cumulative CO2 emissions savings from 1999 to 2016 amount to 38 GtCO2, or one year’s worth of global CO2 output. The impact on other greenhouse gases is much lower. Climate change laws are shown to reduce national CO2 emissions by 0.78% in their first three years and 1.79% in the longer term. These reductions add up to 38 GtCO2 of avoided emissions for 1999–2016—equal to a year of CO2 emissions.