{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). Continued global warming 
is projected to further intensify the global water cycle, including its 
variability, global monsoon precipitation117, and very wet and very dry 
weather and climate events and seasons (high conﬁdence). The portion 
of global land experiencing detectable changes in seasonal mean 
precipitation is projected to increase (medium conﬁdence) with more 
variable precipitation and surface water ﬂows over most land regions 
within seasons (high conﬁdence) and from year to year (medium 
conﬁdence). Many changes due to past and future GHG emissions are 
irreversible118 on centennial to millennial time scales, especially in the 
ocean, ice sheets and global sea level (see 3.1.3). Ocean acidiﬁcation 
(virtually certain), ocean deoxygenation (high conﬁdence) and global 
mean sea level (virtually certain) will continue to increase in the 21st century, 
at rates dependent on future emissions.