68
Section 3
Section 1
Section 3
Section 3: Long-Term Climate and Development Futures
3.1 Long-Term Climate Change, Impacts and Related Risks
Future warming will be driven by future emissions and will affect all major climate system components, with 
every region experiencing multiple and co-occurring changes. Many climate-related risks are assessed to be 
higher than in previous assessments, and projected long-term impacts are up to multiple times higher than 
currently observed. Multiple climatic and non-climatic risks will interact, resulting in compounding and cascading 
risks across sectors and regions. Sea level rise, as well as other irreversible changes, will continue for thousands 
of years, at rates depending on future emissions. (high conﬁdence)
3.1.1. 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.