Long-term Climate Change
The uncertainty range on assessed future changes in global 
surface temperature is narrower than in the AR5. For the ﬁrst 
time in an IPCC assessment cycle, multi-model projections of global 
surface temperature, ocean warming and sea level are constrained 
using observations and the assessed climate sensitivity. The likely 
range of equilibrium climate sensitivity has been narrowed to 2.5°C 
to 4.0°C (with a best estimate of 3.0°C) based on multiple lines of 
evidence112, including improved understanding of cloud feedbacks. For 
related emissions scenarios, this leads to narrower uncertainty ranges 
for long-term projected global temperature change than in AR5. 
{WGI A.4, WGI Box SPM.1, WGI TS.3.2, WGI 4.3}
Future warming depends on future GHG emissions, with 
cumulative net CO2 dominating. The assessed best estimates and 
very likely ranges of warming for 2081-2100 with respect to 1850–1900 
vary from 1.4 [1.0 to 1.8]°C in the very low GHG emissions scenario 
(SSP1-1.9) to 2.7 [2.1 to 3.5]°C in the intermediate GHG emissions 
scenario (SSP2-4.5) and 4.4 [3.3 to 5.7]°C in the very high GHG emissions 
scenario (SSP5-8.5)113. {WGI SPM B.1.1, WGI Table SPM.1, WGI Figure 
SPM.4} (Cross-Section Box.2 Figure 1)
Modelled pathways consistent with the continuation of policies 
implemented by the end of 2020 lead to global warming of 
3.2 [2.2 to 3.5]°C (5–95% range) by 2100 (medium conﬁdence) 
(see also Section 2.3.1). Pathways of >4°C (≥50%) by 2100 would 
imply a reversal of current technology and/or mitigation policy trends 
(medium conﬁdence).