For further explanations of global 
risk levels and Reasons for Concern, see WGII TS.AII. {WGII Figure SPM.3}
changes in food availability and diet quality are estimated to increase 
nutrition-related diseases and the number of undernourished people, 
affecting tens (under low vulnerability and low warming) to hundreds of 
millions of people (under high vulnerability and high warming), particularly 
among low-income households in low- and middle-income countries in 
sub-Saharan Africa, South Asia and Central America (high conﬁdence). 
For example, snowmelt water availability for irrigation is projected 
to decline in some snowmelt dependent river basins by up to 20% 
(medium conﬁdence). Climate change risks to cities, settlements 
and key infrastructure will rise sharply in the mid and long term with 
further global warming, especially in places already exposed to high 
temperatures, along coastlines, or with high vulnerabilities (high 
conﬁdence). {WGII SPM B.3.3, WGII SPM B.4.2, WGII SPM B.4.5, WGII TS C.3.3, 
WGII TS.C.12.2} (Figure 3.3)
At global warming of 3°C, additional risks in many sectors and regions 
reach high or very high levels, implying widespread systemic impacts, 
irreversible change and many additional adaptation limits (see Section 3.2) 
(high conﬁdence). For example, very high extinction risk for endemic 
species in biodiversity hotspots is projected to increase at least tenfold 
if warming rises from 1.5°C to 3°C (medium conﬁdence). Projected 
increases in direct ﬂood damages are higher by 1.4 to 2 times at 2°C 
and 2.5 to 3.9 times at 3°C, compared to 1.5°C global warming without 
adaptation (medium conﬁdence).