Three Decades of Climate Mitigation Policy: What Has It Delivered?

After tentative efforts during the 1990s, the past two decades have seen a rapid increase in the number of greenhouse gas (GHG) emissions mitigation policies, initially in a few frontrunner countries and more recently spreading globally. Over the same period, GHG emissions have continued to rise, but the rate of growth has recently slowed. Are mitigation policies having an effect? To explore this question, we review and synthesize the empirical literature on the impact of mitigation policies on three key outcomes: GHG emissions, proximate emission drivers like energy intensity and land use, and low-carbon technologies. Our key contribution to the available literature lies in establishing an empirically based track record of climate action, focusing on methodologically sound ex post studies. We find that mitigation policies have had a discernible impact on emissions and multiple emission drivers. Most notably, they have led to reductions in energy use, declines in deforestation rates, as well as cost reductions and capacity expansions of low-carbon technologies in many instances. Furthermore, implemented policies to date are likely to have reduced global emissions by several billion tons of CO2eq per year compared to a world without mitigation policies. In the light of current ambitions on climate action falling short of what is required to limit global warming to the Paris temperature goals, we conclude that there is ample evidence of policy instruments with demonstrable impacts, but that efforts need to be hugely strengthened and expanded. Also, far more attention is required to policy monitoring, evaluation, and learning so as to strengthen the basis for future policy and the attribution of its impacts.