By 2020, 
over 20% of global GHG emissions were covered by carbon taxes or 
emissions trading systems, although coverage and prices have been 
insufﬁcient to achieve deep reductions (medium conﬁdence). Equity and 
distributional impacts of carbon pricing instruments can be addressed 
by using revenue from carbon taxes or emissions trading to support 
low-income households, among other approaches (high conﬁdence). 
The mix of policy instruments which reduced costs and stimulated 
adoption of solar energy, wind energy and lithium-ion batteries 
includes public R&D, funding for demonstration and pilot projects, and 
demand-pull instruments such as deployment subsidies to attain scale 
(high conﬁdence) (Figure 2.4). {WGIII SPM B.4.1, WGIII SPM B.5.2, 
WGIII SPM E.4.2, WG III TS.3} 
Mitigation actions, supported by policies, have contributed 
to a decrease in global energy and carbon intensity between 
2010 and 2019, with a growing number of countries achieving 
absolute GHG emission reductions for more than a decade (high 
conﬁdence). While global net GHG emissions have increased since 
2010, global energy intensity (total primary energy per unit GDP) 
decreased by 2% yr–1 between 2010 and 2019. Global carbon 
intensity (CO2-FFI per unit primary energy) also decreased by 0.3% 
yr–1, mainly due to fuel switching from coal to gas, reduced expansion 
of coal capacity, and increased use of renewables, and with large 
regional variations over the same period. In many countries, policies 
have enhanced energy efﬁciency, reduced rates of deforestation and 
accelerated technology deployment, leading to avoided and in some 
cases reduced or removed emissions (high conﬁdence).