As warming levels increase, so do the risks of species extinction or 
irreversible loss of biodiversity in ecosystems such as forests (medium 
conﬁdence), coral reefs (very high conﬁdence) and in Arctic regions 
(high conﬁdence). Risks associated with large-scale singular events 
or tipping points, such as ice sheet instability or ecosystem loss from 
tropical forests, transition to high risk between 1.5°C to 2.5°C (medium 
conﬁdence) and to very high risk between 2.5°C to  4°C (low conﬁdence). 
The response of biogeochemical cycles to anthropogenic perturbations 
can be abrupt at regional scales and irreversible on decadal to century 
time scales (high conﬁdence). The probability of crossing uncertain 
regional thresholds increases with further warming (high conﬁdence). 
{WGI SPM C.3.2, WGI Box TS.9, WGI TS.2.6; WGII Figure SPM.3, 
WGII SPM B.3.1, WGII SPM B.4.1, WGII SPM B.5.2, WGII Table TS.1, 
WGII TS.C.1, WGII TS.C.13.3; SROCC SPM B.4}
Sea level rise is unavoidable for centuries to millennia due 
to continuing deep ocean warming and ice sheet melt, and 
sea levels will remain elevated for thousands of years (high 
conﬁdence). Global mean sea level rise will continue in the 21st 
century (virtually certain), with projected regional relative sea level rise 
within 20% of the global mean along two-thirds of the global coastline 
(medium conﬁdence). The magnitude, the rate, the timing of threshold 
exceedances, and the long-term commitment of sea level rise depend 
on emissions, with higher emissions leading to greater and faster rates 
of sea level rise.