Editing IPCC:AR6/WGIII/Chapter-2 (section)

=== 2.8.2 Comprehensive Multinational Assessments ===

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Comprehensive multinational evaluations with wider regional and sectoral coverage enable the assessment of emissions impacts without distortions from emissions leakage. Among the wide range of climate policy instruments, pricing carbon – such as a carbon tax or an emissions trading system – has been one of the most widely used and effective options to reduce GHG emissions ( ''robust evidence'' , ''high agreement'' ). In a comparison of 142 countries with and without carbon pricing, countries with a carbon price show annual CO 2 emission growth rates of 2 percentage points lower than countries without such policies ( [[#Best--2020|Best et al. 2020]] ). A more comprehensive evaluation of carbon prices shows that countries with a lower carbon pricing gap (a higher carbon price) tend to be more carbon-efficient, that is, they have a lower carbon intensity of GDP (OECD 2018). [[#footnote-000|14]] An empirical analysis of the effects of environmental regulation and innovation on the carbon emissions of OECD countries during the period 1999–2014 indicates that a 1% increase in environmentally friendly patents reduced carbon emissions by 0.017%, and a 1% increase in environmental tax revenue per capita reduced carbon emissions by 0.03% ( [[#Hashmi--2019|Hashmi and Alam 2019]] ).

Domestic and international climate legislation have also contributed to the reduction of GHG emissions. An empirical analysis of legislative activity in 133 countries over the period 1999–2016 based on panel data indicates that each new law reduced annual CO 2 emissions per unit of GDP by 0.78% nationally in the first three years, and by 1.79% beyond three years. Additionally, climate laws as of 2016 were associated with an annual reduction in global CO 2 emissions of 5.9 GtCO 2 and 38 GtCO 2 cumulatively since 1999 ( [[#Eskander--2020|Eskander and Fankhauser 2020]] ). It is notable that 36 countries that accepted legally binding targets under the Kyoto Protocol all complied ( [[#Shishlov--2016|Shishlov et al. 2016]] ). It is impossible to disentangle precisely the contribution of individual mitigation policies, but it is clear that the participating countries, especially those in the OECD, did make substantial policy efforts with material impact ( [[#Grubb--2016|Grubb 2016]] ). An ex-post evaluation shows a significant impact of the Protocol on emissions reductions ( [[#Maamoun--2019|Maamoun 2019]] ).

Renewable energy policies, such as Renewable Portfolio Standards and Feed-in-Tariff, have played an essential role in the massive expansion of renewable energy capacities, another key driver of GHG emissions reductions ( ''robust evidence'' , ''high agreement'' ). Drivers of decreasing CO 2 emissions seen in a group of 18 developed economies that decarbonised over the period 2005–2015 are the displacement of fossil fuels by renewable energy and decreases in energy use ( [[#Le%20Quéré--2019|Le Quéré et al. 2019]] ). Renewable energy policies both at the EU and member states level have played an essential role in abating GHG emissions ( [[#ICF%20International--2016|ICF International 2016]] ).

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