Very high risks to crop production are assessed to occur in Africa above ~2.5℃ warming  and below 4℃ in Europe . Very high risks of mortality and morbidity due to heat extremes and infectious disease are assessed to occur in Africa with 2.5℃ warming ; heat stress, mortality and morbidity in Europe are assessed to reach a very high level of risk at ~3.2℃ . Heat-related mortality risk and cascading effects on cities both transition to a very high level by ~2.5℃ warming in Australasia . Risks to water scarcity in North America are projected to reach very high levels with 3.5℃ warming . Hence, this assessment concludes with medium confidence that a transition from high to very high risks, in terms of distribution of impacts, begins at 2°℃ global warming, with a full transition to very high risks completed by 3.5℃. However, it should be noted that many studies upon which this assessment has been based have not taken into account the impacts of extreme weather events and oscillations in sea surface temperatures; hence, risks at a given level of global warming might be underestimated in the literature.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report