Editing IPCC:AR6/WGII/Chapter-7 (section)

==== 7.3.1.1 Global Impacts ====

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''Climate change is expected to significantly increase the health risks resulting from a range of climate-sensitive diseases and conditions, with the scale of impacts depending on emissions and adaptation pathways in coming decades'' ( ''very high confidence'' ) ''.'' Sections 7.3.1.2 to 7.3.1.11 assess the available studies on future projections for risks associated with specific climate-sensitive diseases and conditions previously described in [[#7.2.1|Section 7.2.1]] . In the case of diabetes, cancer, injuries, mosquito-borne diseases other than dengue and malaria, rodent-borne diseases and most mental illnesses, insufficient literature was found to allow for assessment. Adaptation pathways and options for managing such risks are detailed in [[#7.4|Section 7.4]] .

''Even in the absence of further warming beyond current levels, the proportion of the overall global deaths caused by climate-sensitive diseases and conditions would increase marginally by mid-century'' ( ''high confidence'' ) ''.'' Two global projections of climate change health impacts have been conducted since AR5. The first focused on cause-specific mortality for eight exposures for 2030 and 2050 for a mid-range emissions scenario (A1b) and three scenarios of economic growth ( [[#WHO--2014|WHO, 2014]] ). The study estimated that the climate change projected to occur by 2050 (compared to 1961–1990) could result in an excess of approximately 250,000 deaths yr –1 , dominated by increases in deaths due to heat (94,000, mainly in Asia and high-income countries), childhood undernutrition (85,000, mainly in Africa but also in Asia), malaria (33,000, mainly in Africa) and diarrhoeal disease (33,000, mainly in Africa and Asia). Overall, more than half of this excess mortality is projected for Africa. Near-term projections (for 2030) are predominantly for childhood undernutrition (95,200 out of 241,000 total excess deaths) (Figure 7.8). The second study (Carleton et al. 2020) focused on all-cause mortality associated with warming under both a high emissions scenario (RCP8.5) and a middle emissions scenario (RCP4.5). The analyses created a metric of death equivalents that accounted for hot and cold temperature-related mortality and the costs of individual level adaptation; no acclimatization or community-level adaptation, such as early warning systems, were incorporated. Average annual temperature-mortality-income per capita relationships estimated from pooled data from 40 predominantly middle- and high-income countries (38% of the world population) were applied worldwide. Under the high emissions scenario, climate change was projected to result in approximately 85 deaths equivalents per 100,000 population.

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'''Figure 7.8 |''' '''Projected additional annual deaths attributable to climate change in 2030 and 2050 compared to 1961–1990 ( [[#WHO--2014|WHO, 2014]] ).'''

''Temperature increases are projected to exceed critical risk thresholds for six key climate-sensitive health outcomes, highlighting the criticality of building adaptive capacity in health systems and in other sectors that influence health and well-being'' ( ''high confidence'' ) ''.'' Recently reported research illustrates the temperature thresholds under three adaptation scenarios describing the effectiveness of health systems to manage additional risks from climate change for heat-related morbidity and mortality; ozone-related mortality; malaria incidence rates; incidence rates of Dengue and other diseases spread by Aedes sp. mosquitos; Lyme disease; and West Nile fever ( [[#Ebi--2021a|Ebi et al., 2021a]] ). As shown in Figure 7.9, these adaptation scenarios significantly alter the warming thresholds at which risks accelerate, with the proactive adaptation scenario, a scenario that emphasises international cooperation towards achieving sustainable development, having the greatest potential to avoid significant increases in risks under all but the highest levels of warming. The incomplete adaptation scenario describes a world with moderate challenges to adaptation and mitigation. The limited adaptation scenario describes a world with high challenges to adaptation and mitigation. In the figure, transitions are based on the peer-reviewed literature projecting risks for each of the health outcomes. Projections for time intervals were changed to temperature increase above pre-industrial levels based on the climate models and scenarios used in the projections.The assessed projections were based on a range of scenarios, including SRES, CMIP5, and ISIMIP, and, in some cases, demographic trends. The black dots are levels of confidence, from very high (four dots) to low (one dot). The diagrams for the proactive and incomplete adaptation scenarios are truncated at the nearest whole °C within the range of temperature change in 2100 under three SSP scenarios used in panel (a) of SPM.3.

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'''Figure 7.9 |''' '''Climate-sensitive human health outcomes under three adaptation scenarios.'''

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