{WGII SPM B.3, WGII SPM B.4.1, WGII TS.C.4.2; SR1.5 SPM A.3, 
SR1.5 SPM B.4.2, SR1.5 SPM B.5, SR1.5 SPM B.5.1} (Figure 3.3)
At 2°C of global warming, overall risk levels associated with the unequal 
distribution of impacts (RFC3), global aggregate impacts (RFC4) and 
large-scale singular events (RFC5) would be transitioning to high (medium 
conﬁdence), those associated with extreme weather events (RFC2) would 
be transitioning to very high (medium conﬁdence), and those associated 
with unique and threatened systems (RFC1) would be very high (high 
conﬁdence) (Figure 3.3, panel a). With about 2°C warming, climate-related 
120 Undetectable risk level indicates no associated impacts are detectable and attributable to climate change; moderate risk indicates associated impacts are both detectable and 
attributable to climate change with at least medium conﬁdence, also accounting for the other speciﬁc criteria for key risks; high risk indicates severe and widespread impacts that 
are judged to be high on one or more criteria for assessing key risks; and very high risk level indicates very high risk of severe impacts and the presence of signiﬁcant irreversibility 
or the persistence of climate-related hazards, combined with limited ability to adapt due to the nature of the hazard or impacts/risks. {WGII Figure SPM.3}
121 The Reasons for Concern (RFC) framework communicates scientiﬁc understanding about accrual of risk for ﬁve broad categories (WGII Figure SPM.3). RFC1: Unique and 
threatened systems: ecological and human systems that have restricted geographic ranges constrained by climate-related conditions and have high endemism or other distinctive 
properties. Examples include coral reefs, the Arctic and its Indigenous Peoples, mountain glaciers and biodiversity hotspots.