69
Long-Term Climate and Development Futures
Section 3
policies limit this additional warming and lead to strong beneﬁts 
for air quality (high conﬁdence). In high and very high GHG 
emissions scenarios (SSP3-7.0 and SSP5-8.5), combined changes 
in SLCF emissions, such as CH4, aerosol and ozone precursors, lead to a 
net global warming by 2100 of likely 0.4°C to 0.9°C relative to 2019. 
This is due to projected increases in atmospheric concentration of CH4, 
tropospheric ozone, hydroﬂuorocarbons and, when strong air pollution 
control is considered, reductions of cooling aerosols. In low and very 
low GHG emissions scenarios (SSP1-1.9 and SSP1-2.6), air pollution 
control policies, reductions in CH4 and other ozone precursors lead to a 
net cooling, whereas reductions in anthropogenic cooling aerosols lead 
to a net warming (high conﬁdence). Altogether, this causes a likely net 
warming of 0.0°C to 0.3°C due to SLCF changes in 2100 relative to 2019 
and strong reductions in global surface ozone and particulate matter 
(high conﬁdence). {WGI SPM D.1.7, WGI Box TS.7} (Cross-Section Box.2)
Continued GHG emissions will further affect all major climate 
system components, and many changes will be irreversible on 
centennial to millennial time scales. Many changes in the climate 
system become larger in direct relation to increasing global warming. 
With every additional increment of global warming, changes in 
extremes continue to become larger. Additional warming will lead to 
more frequent and intense marine heatwaves and is projected to further 
amplify permafrost thawing and loss of seasonal snow cover, glaciers, 
land ice and Arctic sea ice (high conﬁdence).