Editing IPCC:AR6/WGII/Chapter-9 (section)

=== 9.10.2 Observed Impacts and Projected Risks ===

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Climate change is already impacting certain health outcomes in Africa (e.g. temperature-related mortality) and risks for most (but not all) health outcomes are projected to increase with increasing global warming (Figure 9.32), with young children (&lt;5 years old), the elderly (&gt;65 years old), pregnant women, individuals with pre-existing morbidities, physical labourers and people living in poverty or affected by other socioeconomic determinants of health being the most vulnerable ( ''high confidence'' ). Women may be more vulnerable to climate change impacts than men ( [[#Chersich--2018|Chersich et al., 2018]] ; [[#Jaka--2018|Jaka and Shava, 2018]] ; [[#Adzawla--2019a|Adzawla et al., 2019a]] ). Contextualising projected impacts of climate change on health requires an understanding of observed impacts (Figure 9.32). Without management and mitigation, current and projected morbidities and mortalities will put additional strain on health, social and economic systems ( [[#Hendrix--2017|Hendrix, 2017]] ; [[#Alonso--2019|Alonso et al., 2019]] ).

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[[File:e24ed673b91ed1600aaa6915f3d4bda4 IPCC_AR6_WGII_Figure_9_032.png]]

'''Figure 9.32 |''' '''Risks to health in Africa increase with increasing global warming.''' Observed climate impacts and projected climate change risks across African regions for eight key health outcomes. Global warming levels shown refer to increases relative to pre-industrial values (1850–1900). This list of health impacts and risks is not intended to be exhaustive, but instead focuses on well-documented conditions. This assessment is a synthesis across 58 studies on observed impacts and 29 studies on projected risks for health (see Table SM 9.7). The category of air pollution-related health outcomes includes health impacts from changing particulate matter concentrations due to climate change.

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==== 9.10.2.1 Vector-borne Diseases ====

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===== 9.10.2.1.1 Malaria =====

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Observed impacts

Higher temperatures and shifting patterns of rainfall influence the distribution and incidence of malaria in sub-Saharan Africa ( ''high confidence'' ) ( [[#Agusto--2015|Agusto et al., 2015]] ; [[#Beck-Johnson--2017|Beck-Johnson et al., 2017]] ). Up to 10.9 million km 2 of sub-Saharan Africa is optimally suitable for year-round malaria transmission ( [[#Mordecai--2013|Mordecai et al., 2013]] ; [[#Ryan--2015|Ryan et al., 2015]] ). Current climate suitability for endemic malaria transmission is concentrated in the central African region, some areas along the southern coast of west Africa and the east African coast ( [[#Ryan--2020|Ryan et al., 2020]] ).

In east Africa, there has been an expansion of the ''Anopheles'' vector into higher altitudes ( [[#Gone--2014|Gone et al., 2014]] ; [[#Carlson--2019|Carlson et al., 2019]] ) and increasing incidence of infection with ''Plasmodium falciparum'' with higher temperatures ( ''high confidence'' ) ( [[#Alemu--2014|Alemu et al., 2014]] ; [[#Lyon--2017|Lyon et al., 2017]] ). Over southern Africa, changes in temperature and rainfall are increasing malaria transmission ( [[#Abiodun--2018|Abiodun et al., 2018]] ). In west Africa, studies show both positive ( [[#Adu-Prah--2015|Adu-Prah and Kofi Tetteh, 2015]] ; [[#Darkoh--2017|Darkoh et al., 2017]] ) and negative ( [[#M’Bra--2018|M’Bra et al., 2018]] ) correlations of malaria incidence with increases in mean monthly temperatures, and an abundance of ''Anopheles gambiae'' s.s. associated with mean diurnal temperature ( [[#Akpan--2018|Akpan et al., 2018]] ).

Malaria incidence and outbreaks in east Africa were linked with both moderate monthly rainfall and extreme flooding ( [[#Boyce--2016|Boyce et al., 2016]] ; [[#Amadi--2018|Amadi et al., 2018]] ; [[#Simple--2018|Simple et al., 2018]] ), and increase 1–2 months after periods of rainfall in southern and west Africa ( [[#Diouf--2017|Diouf et al., 2017]] ; [[#Ferrão--2017|Ferrão et al., 2017]] ; [[#Adeola--2019|Adeola et al., 2019]] ). The years following La Niña events (southern Africa) ( [[#Adeola--2017|Adeola et al., 2017]] )) and high relative humidity (west Africa) ( [[#Adu-Prah--2015|Adu-Prah and Kofi Tetteh, 2015]] ; [[#Darkoh--2017|Darkoh et al., 2017]] ) have been positively linked with malaria incidence.

Projected risks

Since AR5, significant progress has been made in understanding how changes in climate influence the seasonal and geographical range of malaria vectors, transmission intensity and burden of disease of malaria across Africa. Yet projecting changes remains challenging given the range of factors that influence transmission and disease patterns, and model outputs contain high degrees of uncertainty ( [[#Zermoglio--2019|Zermoglio et al., 2019]] ; [[#Giesen--2020|Giesen et al., 2020]] ). Models have limited ability to account for population changes and development trends ( [[#Kibret--2015|Kibret et al., 2015]] ; 2017), investments in health sectors and interventions ( [[#McCord--2016|McCord, 2016]] ; [[#Colborn--2018|Colborn et al., 2018]] ; [[#Caminade--2019|Caminade et al., 2019]] ), and confounders such as age, socioeconomic status, employment, labour migration and climate variability ( [[#Bennett--2016|Bennett et al., 2016]] ; [[#Karuri--2016|Karuri and Snow, 2016]] ; [[#Byass--2017|Byass et al., 2017]] ; [[#Chuang--2017|Chuang et al., 2017]] ; [[#Colborn--2018|Colborn et al., 2018]] ). Nevertheless, available models do allow for projections of malaria transmission under different climate change scenarios to be made with high levels of certainty.

In east and southern Africa and the Sahel, malaria vector hotspots and prevalence are projected to increase under RCP4.5 and RCP8.5 by 2030 (1.5°C–1.7°C global warming) ( ''high confidence'' ) ( [[#Leedale--2016|Leedale et al., 2016]] ; [[#Semakula--2017b|Semakula et al., 2017b]] ; [[#Zermoglio--2019|Zermoglio et al., 2019]] ), becoming more pronounced later in the century (2.4°C–3.9°C global warming) ( [[#Ryan--2020|Ryan et al., 2020]] ). Under RCP4.5, 50.6–62.1 million people in east and southern Africa will be at risk of malaria by the 2030s (1.5°C global warming), and 196–198 million by the 2080s (2.4°C global warming) ( [[#Ryan--2020|Ryan et al., 2020]] ). Northern Angola, southern DRC, western Tanzania and central Uganda are predicted to be worst impacted in 2030, extending to western Angola, upper Zambezi River basin, northeastern Zambia and the east African Highlands by 2080 ( [[#Ryan--2020|Ryan et al., 2020]] ). Under rising temperatures, by the 2050s, the greatest shifts in suitability for malaria transmission will be seen in east, southern and central Africa (2°C global warming) ( [[#Tonnang--2014|Tonnang et al., 2014]] ; [[#Zermoglio--2019|Zermoglio et al., 2019]] ; [[#Ryan--2020|Ryan et al., 2020]] ).

Conversely, in some regions, changing climatic conditions are projected to reduce malaria hotspots and prevalence. With continued GHG emissions, these include: west Africa by 2030 (1.7°C global warming) ( ''high confidence'' ) ( [[#Yamana--2016|Yamana et al., 2016]] ; [[#Semakula--2017b|Semakula et al., 2017b]] ; [[#Ryan--2020|Ryan et al., 2020]] ), parts of southern central Africa and dryland regions in east Africa by 2050 (2.5°C global warming) ( ''high confidence'' ) ( [[#Semakula--2017b|Semakula et al., 2017b]] ; [[#Ryan--2020|Ryan et al., 2020]] ) and large areas of southern central Africa and the western Sahel by 2100 (&gt;4°C global warming) ( [[#Yu--2015|Yu et al., 2015]] ; [[#Tourre--2019|Tourre et al., 2019]] ). These reductions in transmission correspond with decreasing environmental suitability for the malaria vector and parasite in these regions ( [[#Ryan--2015|Ryan et al., 2015]] ; [[#Mordecai--2020|Mordecai et al., 2020]] ). Most areas in Burkina Faso, Cameroon, Ivory Coast, Ghana, Niger, Nigeria, Sierra Leone, Zambia and Zimbabwe will have almost zero malaria transmission under RCP8.5 ( [[#Semakula--2017b|Semakula et al., 2017b]] ; [[#Tourre--2019|Tourre et al., 2019]] ).

The ENSO cycle currently contributes to seasonal epidemic malaria in epidemic-prone areas ( ''high confidence'' ), and is projected to shift the malaria epidemic fringe southward and into higher altitudes by mid- to end-century ( ''high confidence'' ) ( [[#Bouma--2016|Bouma et al., 2016]] ; [[#Semakula--2017b|Semakula et al., 2017b]] ; [[#Caminade--2019|Caminade et al., 2019]] ). More evidence is needed, however, of climate variability impacts through ENSO cycles in future risk projections, as well as a deeper understanding of how climate change will impact the length of transmission season for mosquitoes, particularly in areas where increases in spring and autumn temperatures may increase suitability for the reproduction of malaria vectors ( [[#Ryan--2020|Ryan et al., 2020]] ). Other gaps in knowledge include a better understanding of mosquito thermal biology and thermal limits for a variety of species, potential adaptations to extreme temperatures and how landscape changes contribute to malaria transmission ( [[#Tompkins--2016|Tompkins and Caporaso, 2016]] ).

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===== 9.10.2.1.2 Mosquito-borne viruses =====

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Observed impacts

Climate variability has driven a global intensification of mosquito-borne viruses (e.g., dengue, Zika and RVF), including expansion into areas with higher altitudes ( [[#Leedale--2016|Leedale et al., 2016]] ; [[#Mweya--2016|Mweya et al., 2016]] ; [[#Messina--2019|Messina et al., 2019]] ). Concerns centre on diseases vectored by the yellow fever mosquito ( ''Aedes aegypti'' ), common throughout most of sub-Saharan Africa, and the tiger mosquito ( ''Aedes albopictus'' ), currently largely confined to western central Africa ( [[#Kraemer--2019|Kraemer et al., 2019]] ; [[#Mordecai--2020|Mordecai et al., 2020]] ).

Although warming temperatures are largely responsible for increasing environmental suitability for mosquito vectors ( [[#Mordecai--2019|Mordecai et al., 2019]] ), droughts can augment transmission when open water storage provides breeding sites near human settlements, and when flooding enables mosquitoes to proliferate and spread viruses further ( [[#Mweya--2017|Mweya et al., 2017]] ; [[#Bashir--2019|Bashir and Hassan, 2019]] ). Within Africa’s rapidly growing cities, diseases vectored by urban-adapted ''Aedes'' mosquitoes pose a major threat, especially in west Africa ( [[#Zahouli--2017|Zahouli et al., 2017]] ; [[#Weetman--2018|Weetman et al., 2018]] ; [[#Messina--2019|Messina et al., 2019]] ). Dengue virus expansion may cause explosive outbreaks but the burden of dengue haemorrhagic fever and associated mortality is higher in areas where transmission is already endemic ( [[#Murray--2013|Murray et al., 2013]] ).

Projected risks

Populations of ''Aedes aegypti'' and ''Aedes albopictus'' mosquitoes and epidemics of dengue and yellow fever and other ''Aedes'' -borne viruses are expected to increase, including at high altitudes ( [[#Weetman--2018|Weetman et al., 2018]] ; [[#Messina--2019|Messina et al., 2019]] ; [[#Ryan--2019|Ryan et al., 2019]] ; [[#Gaythorpe--2020|Gaythorpe et al., 2020]] ; [[#Mordecai--2020|Mordecai et al., 2020]] ). ''Aedes albopictus'' may expand beyond western central Africa into Chad, Mali and Burkina Faso by mid-century at &gt;2°C global warming ( [[#Kraemer--2019|Kraemer et al., 2019]] ). Shifts projected in ''Aedes'' range due to changing environmental suitability, combined with rapid urbanisation and population growth, suggest that by 2050 populations exposed to these vectors in Africa may double, and by 2080 nearly triple at &gt;2°C global warming ( [[#Kraemer--2019|Kraemer et al., 2019]] ). Southern limits of dengue transmission in Namibia and Botswana, and the western Sahel, may show the greatest expansions in environmental suitability under 1.8°C–2.6°C global warming ( [[#Messina--2019|Messina et al., 2019]] ). In the warmest scenarios (RCP8.5), however, some parts of central Africa may become too hot for mosquitoes to transmit dengue, and thus at-risk populations may peak at intermediate warming levels ( [[#Ryan--2019|Ryan et al., 2019]] ). Climatic conditions favourable for mosquitoes, combined with the increase of animal trade, may result in the expansion of the geographic range of zoonotic diseases like RVF ( [[#Martin--2008|Martin et al., 2008]] ), a threat for human and animal health with strong socioeconomic impacts ( [[#Peyre--2015|Peyre et al., 2015]] ).

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<span id="diarrhoeal-diseases-hiv-and-other-infectious-diseases"></span>
==== 9.10.2.2 Diarrhoeal Diseases, HIV and Other Infectious Diseases ====

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===== 9.10.2.2.1 Diarrhoeal diseases =====

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Observed impacts

Africa has the highest rates of death due to diarrhoeal diseases in the world ( [[#Havelaar--2015|Havelaar et al., 2015]] ; [[#Troeger--2018|Troeger et al., 2018]] ) and many children have repeated diarrhoeal episodes with impaired growth, stunting, immune dysfunction and reduced cognitive performance ( [[#Squire--2017|Squire and Ryan, 2017]] ). High land and sea temperatures ( [[#Paz--2009|Paz, 2009]] ; [[#Musengimana--2016|Musengimana et al., 2016]] ) and precipitation extremes increase transmission of bacterial and protozoal diarrhoeal disease agents ( [[#Boeckmann--2019|Boeckmann et al., 2019]] ) through contamination of drinking water and food preparation and preservation practices (Figure 9.33; [[#Levy--2016|Levy et al., 2016]] ; [[#Soneja--2016|Soneja et al., 2016]] ; [[#Walker--2018|Walker, 2018]] ).

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[[File:c3b4526bd1974f2e1a69e02691601cc4 IPCC_AR6_WGII_Figure_9_033.png]]

'''Figure 9.33 |''' '''Schematic showing the pathways to diarrhoeal disease impacts in Africa as a result of exposure to climate hazards.''' Numbers in the figure refer to chapter sections of this report.

Cholera incidence has been shown to increase with temperature ( [[#Trærup--2011|Trærup et al., 2011]] ). Outbreaks, however, are most frequent in east and southern Africa following tropical cyclones ( [[#Moore--2017b|Moore et al., 2017b]] ; [[#Troeger--2018|Troeger et al., 2018]] ; [[#Ajayi--2019|Ajayi and Smith, 2019]] ; [[#Cambaza--2019|Cambaza et al., 2019]] ).

Africa’s rapidly urbanising population increases the demand for freshwater and is occurring in places that already have stretched water and sanitation infrastructure ( [[#Howard--2016|Howard et al., 2016]] ). These conditions, especially during periods of water scarcity, can reduce the frequency and adequacy of hand washing and thereby increase disease transmission.

Projected risks

Disruptions in water availability, such as during droughts or infrastructure breakdown, will jeopardise access to safe water and adequate sanitation, undermine hygiene practices and increase environmental contamination with toxins ( [[#Howard--2016|Howard et al., 2016]] ; [[#WWF-SA--2016|WWF-SA, 2016]] ; [[#Miller--2017|Miller and Hutchins, 2017]] ).

Climate change is projected to cause 20,000–30,000 additional diarrhoeal deaths in children (&lt;15 years old) by mid-century under 1.5°C–2.1°C global warming ( [[#WHO--2014|WHO, 2014]] ), with west Africa most affected, followed by east, central and southern Africa. Cholera outbreaks are anticipated to impact east Africa most severely during and particularly after ENSO events ( [[#Moore--2017b|Moore et al., 2017b]] ).

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===== 9.10.2.2.2 HIV =====

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Observed impacts

Although levels of new HIV infections declined sharply during the last decade, still more than a million adults and children become infected each year ( [[#UNAIDS--2020|UNAIDS, 2020]] ). Climate influences on HIV are predominately indirect such as through heightened migration due to climate variability, or extreme weather events leading to increased transactional sex to replace lost sources of income. Changes in climate affect each of the main drivers of HIV transmission in women, including poverty, inequity and gender-based violence ( [[#Burke--2015a|Burke et al., 2015a]] ; [[#Loevinsohn--2015|Loevinsohn, 2015]] ; [[#Fiorella--2019|Fiorella et al., 2019]] ).

Projected risks

‘Oscillating’ or ‘circular’ migration for migrant workers in urban and mining centres drove HIV transmission in the 1990s and 2000s ( [[#Lurie--2006|Lurie, 2006]] ), and climate-related displacement may have similar effects (See Box 9.7; [[#Gray--2012|Gray and Mueller, 2012]] ; [[#Loevinsohn--2015|Loevinsohn, 2015]] ; [[#Low--2019|Low et al., 2019]] ). Food insecurity and nutritional deficiencies, projected to increase with increasingly variable climates, has been shown to increase sexual risk-taking and migration, as well as increase susceptibility to other infections ( [[#Lieber--2021|Lieber et al., 2021]] ). Projected increases in exposure to infectious diseases pose considerable threats to HIV-infected people who may already have compromised immune function. Additionally, reduced lung function in people with HIV from previous tuberculosis infection may put them at high risk for morbidity and death during extreme heat ( [[#Abayomi--2014|Abayomi and Cowan, 2014]] ). Moreover, extreme weather events accompanied by damage to health system infrastructure could compromise the continuity of antiretroviral treatment ( [[#Weiser--2010|Weiser et al., 2010]] ; [[#Pozniak--2020|Pozniak et al., 2020]] ).

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===== 9.10.2.2.3 Other infectious diseases =====

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Poor populations in the western Sahel have the highest burden of bacterial meningitis worldwide, with seasonal dynamics driven by the dry Harmattan winds that transport dust long distances across the continent ( [[#Agier--2013|Agier et al., 2013]] ; [[#García-Pando--2014|García-Pando et al., 2014]] ). In Nigeria, rising temperatures are projected to increase meningitis cases by about 50% for 1.8°C global warming (RCP2.6 in 2060–2075), and by almost double for 3.4°C global warming (RCP8.5 in 2060–2075) ( [[#Abdussalam--2014|Abdussalam et al., 2014]] ). Bilharzia is also highly climate sensitive, with its distribution influenced by changes in temperature and precipitation, as well as development, such as the introduction of freshwater projects (e.g., canals, hydroelectric dams and irrigation schemes) ( [[#Adekiya--2019|Adekiya et al., 2019]] ).

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[[File:c76500349e5e3c91f4ab4e3e17ec73d2 IPCC_AR6_WGII_Figure_9_034.png]]

'''Figure 9.34 |''' '''Schematic showing the pathways of impact for heat-related morbidities in Africa as a result of exposure to climate hazards.''' Numbers in the figure refer to chapter sections of this report. Indirect health impacts of heat are not shown. For example, risk of malnutrition from reduced crop yields or reduced fisheries catches (see [[#9.8.5|Section 9.8.5]] ).

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==== 9.10.2.3 Temperature-related Impacts ====

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===== 9.10.2.3.1 Mortality and morbidity =====

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Observed impacts

Emergency department visits and hospital admissions have been shown to increase at moderate-to-high temperatures ( [[#Bishop-Williams--2018|Bishop-Williams et al., 2018]] ; [[#van%20der%20Linden--2019|van der Linden et al., 2019]] ), with increased levels of mortality recorded on days with raised temperatures in Burkina Faso ( [[#Kynast-Wolf--2010|Kynast-Wolf et al., 2010]] ; [[#Diboulo--2012|Diboulo et al., 2012]] ; [[#Bunker--2017|Bunker et al., 2017]] ), Ghana ( [[#Azongo--2012|Azongo et al., 2012]] ), Kenya ( [[#Egondi--2012|Egondi et al., 2012]] ; [[#Egondi--2015|Egondi et al., 2015]] ), South Africa ( [[#Wichmann--2017|Wichmann, 2017]] ; [[#Scovronick--2018|Scovronick et al., 2018]] ), Tanzania ( [[#Mrema--2012|Mrema et al., 2012]] ) and Tunisia ( [[#Bettaieb--2010|Bettaieb et al., 2010]] ; [[#Leone--2013|Leone et al., 2013]] ). Cause of death most commonly involves cardiovascular diseases ( [[#Kynast-Wolf--2010|Kynast-Wolf et al., 2010]] ; [[#Scovronick--2018|Scovronick et al., 2018]] ), but increased incidences of respiratory ( [[#Scovronick--2018|Scovronick et al., 2018]] ), stroke ( [[#Longo-Mbenza--1999|Longo-Mbenza et al., 1999]] ) and non-communicable diseases ( [[#Bunker--2017|Bunker et al., 2017]] ) have also been linked with heat.

Excess death rates from non-optimal temperature in sub-Saharan Africa are estimated to be nearly double the global average, with 24% of the more than 5 million annual deaths globally associated with non-optimal temperature occurring in Africa ( [[#Zhao--2021|Zhao et al., 2021]] ). The region had the world’s highest cold-related excess death ratio and lowest heat-related excess death ratio over the period 2000–2019. However, during this time, cold-related excess deaths declined more rapidly than the increase in heat-related excess deaths, resulting in a net decrease in the excess death ratio from temperature.

Recent estimates of the burden of mortality associated with the additional heat exposure from recent human-caused global warming suggest approximately 43.8% of heat-related mortality in South Africa was attributable to human-caused climate change from 1991–2018 ( [[#Vicedo-Cabrera--2021|Vicedo-Cabrera et al., 2021]] ). In many of South Africa’s 52 districts, this equates to dozens of deaths per year. The elderly and children under 5 years are most vulnerable to heat exposure ( [[#Sewe--2015|Sewe et al., 2015]] ; [[#Scovronick--2018|Scovronick et al., 2018]] ).

Projected risks

Globally, Africa is predicted to suffer disproportionately from higher temperature-related all-cause mortality from global warming, compared to temperate northern hemisphere countries ( [[#Carleton--2018|Carleton et al., 2018]] ). The number of days projected to exceed potentially lethal heat thresholds per year reaches 50–150 days in west Africa at 1.6°C global warming, up to 200 days in west Africa and 100–150 days in central Africa and parts of coastal east Africa at 2.5°C, and over 200 days for parts of west, central and east Africa for &gt;4°C global warming ( [[#Mora--2017|Mora et al., 2017]] ; see Sections 9.5.3–7; Figure 9.15). Projected rates of heat-related mortality among people in the Middle East and north Africa who are older than 65 years increase by 8–20 fold in 2070–2099, compared with 1951–2005, based on RCP4.5 and RCP8.5 (both at &gt;2°C global warming) ( [[#Ahmadalipour--2018|Ahmadalipour and Moradkhani, 2018]] ).

Temperature-related mortality across Africa is projected to escalate with global warming. Above 1.5°C the risk of heat-related deaths rises sharply, with at least 15 additional deaths per 100,000 annually across large parts of Africa, reaching 50–180 additional deaths per 100,000 people annually in regions of north, west, and east Africa for 2.5°C global warming, and increasing to 200–600 per 100,000 people annually for 4.4°C global warming (Figure 9.35; [[#Carleton--2018|Carleton et al., 2018]] ). However, some regions that currently experience cold-related mortality (e.g., Lesotho and Ethiopian Highlands) are projected to have reduced temperature-related mortality risk from warming. GHG mitigation is projected to save tens of thousands of lives: limiting warming to RCP4.5 (2.5°C) rather than RCP8.5 (4.4°C) at the end of the century is projected to avoid on average 71 deaths per 100,000 people annually across Africa with larger reductions in risk in north, west, central and parts of east Africa (Figure 9.35). The cost of mitigating heat stress using energy-intensive cooling methods is expected to be unachievable for many African countries ( [[#Parkes--2019|Parkes et al., 2019]] ; see [[#9.9.4|Section 9.9.4]] ).

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[[File:3befb6fd3a7817461be84909a3b23a3c IPCC_AR6_WGII_Figure_9_035.png]]

'''Figure 9.35 |''' '''Projected temperature-related mortality risk in Africa with increasing global warming.''' Maps show changes in mortality rates in deaths per 100,000 for global warming in the years 2020–2039, 2040–2059 and 2080–2099 for

'''(a)''' intermediate emissions scenario (RCP 4.5);

'''(b)''' a high emissions scenario (RCP 8.5); and

'''(c)''' showing avoidable deaths due to increased emissions mitigation efforts to achieve a lower global warming level (RCP4.5 rather than RCP8.5). These estimates of climate change impacts on mortality rates include temperature-related impacts only. They account for the benefits of income growth and incremental adaptation to climate change, both of which reduce mortality sensitivity to extreme temperatures. Projections were based on income and demographics from Shared Socioeconomic Pathway 3 (SSP3), with future adaptation based on adaptation actions observed in the global historical record. The estimates do not include the costs of the behaviours and investments required to achieve such adaptation ( [[#Carleton--2018|Carleton et al., 2018]] ). Areas shown in burgundy in (c) have fewer deaths due to temperature under RCP8.5 than RCP4.5. This is because cold is currently the greatest driver of temperature-related deaths in these areas, which is projected to be alleviated with increasing levels of global warming ( [[#Zhao--2021|Zhao et al., 2021]] ).

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===== 9.10.2.3.2 Heat stress in specific settings =====

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Heat stress symptoms are prevalent among people in buildings that are poorly ventilated or insulated, or constructed with unsuitable materials (e.g., corrugated metal sheeting). These features are common to many structures in Africa, including slums, informal and low-income settlements, as well as schools and healthcare facilities ( [[#Bidassey-Manilal--2016|Bidassey-Manilal et al., 2016]] ; [[#Naicker--2017|Naicker et al., 2017]] ; [[#Wright--2019|Wright et al., 2019]] ). Temperatures inside these structures can exceed outdoor temperatures by 4°C or more and have large diurnal fluctuations ( [[#Mabuya--2020|Mabuya and Scholes, 2020]] ). Daily wage labourers and residents of urban informal settlements are among the most vulnerable to heat stress because of the urban heat island effect, with congestion, and inadequate ventilation, shade, open space and vegetation ( [[#Bartlett--2008|Bartlett, 2008]] ) being associated with impacts of both hot and cold conditions on public health ( [[#Ramin--2009|Ramin, 2009]] ). Temperature extremes are ''expected'' to result in relatively more deaths in informal settlements than in other settlement types ( [[#Scovronick--2012|Scovronick and Armstrong, 2012]] ).

The urban heat island effect exacerbates current and projected heat stress in Africa’s rapidly growing cities ( [[#Mitchell--2016|Mitchell, 2016]] ) and is discussed in more detail in [[#9.9.3|Section 9.9.3]] .

Escalating temperatures and longer-duration heatwaves are ''expected'' to heavily affect workers already exposed to extreme temperatures, for example, outdoor workers ( [[#Kjellstrom--2018|Kjellstrom et al., 2018]] ) and miners ( [[#El-Shafei--2018|El-Shafei et al., 2018]] ; [[#Nunfam--2019a|Nunfam et al., 2019a]] ; [[#Nunfam--2019b|Nunfam et al., 2019b]] ). Vulnerability may also be high for women who cook food for a living, and children who accompany them, due to prolonged exposure to high temperatures ( [[#Parmar--2019|Parmar et al., 2019]] ). Prisons, commonly poorly ventilated and overcrowded, are also high-risk settings ( [[#Van%20Hout--2019|Van Hout and Mhlanga-Gunda, 2019]] ).

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===== 9.10.2.3.3 Maternal and child health =====

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Exposure to high temperatures during pregnancy has been linked with adverse birth outcomes, including stillbirths or miscarriages ( [[#Asamoah--2018|Asamoah et al., 2018]] ) and long-term behavioural and developmental deficiencies ( [[#Duchoslav--2017|Duchoslav, 2017]] ; [[#MacVicar--2017|MacVicar et al., 2017]] ).

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==== 9.10.2.4 Impacts of Extreme Weather ====

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During extreme conditions, for example, Cyclone Kenneth ( [[#Codjoe--2020|Codjoe et al., 2020]] ) and El Niño 2015–2016 ( [[#WHO--2016|WHO, 2016]] ; [[#Pozniak--2020|Pozniak et al., 2020]] ), direct physical injury, loss of life, destruction of property and population displacement can occur. Flooding and landslides are common after extreme rainfall and are the most frequently described impact of climate variability in Africa’s cities currently, with residents of poorly serviced or informal settlements most vulnerable ( [[#Hunter--2020|Hunter et al., 2020]] ). Post-traumatic stress disorders in affected individuals are common, including in children ( [[#Rother--2020|Rother, 2020]] ). In rural areas, the resulting damage to health facilities, access routes and transport services can severely compromise health service delivery ( [[#WHO--2016|WHO, 2016]] ). The effects of extreme weather on urban health infrastructure depends on the characteristics, location and adaptive capacity of cities (see [[#9.9.4|Section 9.9.4]] ).

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==== 9.10.2.5 Malnutrition ====

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<span id="observed-impacts"></span>
===== 9.10.2.5.1 Observed impacts =====

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Africa has experienced the greatest impacts of climate change on acute food insecurity and malnutrition ( [[#FAO%20and%20ECA--2018|FAO and ECA, 2018]] ). Adverse climatic conditions exacerbate the impacts of an unstable global economy, conflict and pandemics on food insecurity ( [[#AfDB--2018b|AfDB, 2018b]] ; [[#Food%20Security%20Information%20Network%20(FSIN)--2019|Food Security Information Network (FSIN), 2019]] ; [[#Fore--2020|Fore et al., 2020]] ; see [[IPCC:Wg2:Chapter:Chapter-5|Chapter 5]] [[IPCC:Wg2:Chapter:Chapter-5#5.12.4|Section 5.12.4]] ).

More than 250 million Africans are undernourished, mostly in central and east Africa (FAO et al., 2020), which increases childhood stunting, affects cognition and has trans-generational sequelae ( [[#IFPRI--2016|IFPRI, 2016]] ; UNICEF et al., 2019). Undernutrition is strongly linked with hot climates ( [[#Hagos--2014|Hagos et al., 2014]] ; [[#Tusting--2020|Tusting et al., 2020]] ). In Burkina Faso, low crop yields resulted in around 110 deaths per 10,000 children under 5 years, with 72% of this impact attributable to adverse climate conditions in the growing season ( [[#Belesova--2019|Belesova et al., 2019]] ).

Increasing incidence and expanded distributions of vector-borne livestock diseases (e.g., bluetongue, trypanosomiasis and RVF) in response to changes in rainfall and increasing temperatures, undermine food security, especially among subsistence farmers ( [[#Samy--2016|Samy and Peterson, 2016]] ; [[#Caminade--2019|Caminade et al., 2019]] ). Locust infestations linked with changes in climate ( [[#Salih--2020|Salih et al., 2020]] ) are a major risk for food security in Africa.

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===== 9.10.2.5.2 Projected risks =====

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Projected risks for malnutrition in Africa are high ( [[#FAO--2016|FAO, 2016]] ; see [[#9.8.1|Section 9.8.1]] ): 433 million people in Africa are anticipated to be undernourished by 2030 (FAO et al., 2020) and, compared to 1961–1990, 1.4 million additional African children will suffer from severe stunting by 2050 under 2.1°C global warming ( [[#WHO--2014|WHO, 2014]] ). In Burkina Faso, the mortality burden due to low crop yields could double by 2100 with 1.5°C of global warming ( [[#Belesova--2019|Belesova et al., 2019]] ). Drought risks will include crop and livestock failures ( [[#Ahmadalipour--2019|Ahmadalipour et al., 2019]] ). Additionally, increasing concentrations of atmospheric CO 2 will affect the nutritional quality of C 3 plant staples, lowering levels of protein and minerals like zinc and iron ( [[#Myers--2014|Myers et al., 2014]] ; [[#Weyant--2018|Weyant et al., 2018]] ). Declining fish catches due to ocean warming, illegal fishing and poor stock management are projected to increase deficiencies of zinc, iron and vitamin A for millions of people across Mozambique, Angola and multiple west African countries (see [[#9.8.5|Section 9.8.5]] ; [[#Golden--2016|Golden et al., 2016]] ).

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<span id="non-communicable-diseases-and-mental-health"></span>
==== 9.10.2.6 Non-communicable Diseases and Mental Health ====

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Links between climate change and the environmental risk factors for non-communicable diseases (NCDs) may be direct (e.g., extreme heat exposure in people with cardiovascular disease) or indirect, such as via the global agriculture and food industry ( [[#Landrigan--2018|Landrigan et al., 2018]] ). These effects are largely unreported for Africa ( [[#Amegah--2016|Amegah et al., 2016]] ), where the burden of many NCDs is growing rapidly with increasing urbanisation and pollution ( [[#Rother--2020|Rother, 2020]] ).

Many urban poor populations have unhealthy dietary practices, which present major risks for obesity, type II diabetes and hypertension. Paradoxically, despite growing levels of undernutrition, the incidence of overweight and obesity continues to rise in Africa, particularly in children under 5 years from the northern and southern parts of the continent ( [[#FAO%20and%20ECA--2018|FAO and ECA, 2018]] ). Diabetes is increasingly prevalent and outcomes may worsen if climate change undermines health infrastructure and the range of available foods ( [[#Keeling--2012|Keeling et al., 2012]] ; [[#Kula--2013|Kula et al., 2013]] ; [[#Chersich--2019|Chersich and Wright, 2019]] ).

The relationship between cancer and climate change is complex and indirect. Changing temperature and humidity may alter the distribution of aflatoxin-producing fungi, contaminating food (grains, maize) and causing cancer (see Box 5.9 in Chapter 5; [[#Sserumaga--2020|Sserumaga et al., 2020]] ; [[#Valencia-Quintana--2020|Valencia-Quintana et al., 2020]] ). Severe storms and flooding may disrupt wastewater treatment or disposal, potentially contaminating drinking water with carcinogenic substances.

Areas with low service provision (e.g., informal settlements in Africa) suffer from increased infestations of pests such as flies, cockroaches, rats, bedbugs and lice, which may be controlled by chemical pesticides ( [[#Rother--2020|Rother et al., 2020]] ) and may become more prevalent with a changing climate ( [[#Mafongoya--2019|Mafongoya et al., 2019]] ). Inappropriate pesticide use and disposal cause endocrine disruption and increased incidences of some cancers ( [[#Rother--2020|Rother et al., 2020]] ).

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===== 9.10.2.6.1 Mental health and well-being =====

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Mental health and well-being are affected by local climate conditions and are therefore sensitive to climate change ( [[#Burke--2018b|Burke et al., 2018b]] ; [[#Obradovich--2018|Obradovich et al., 2018]] ). High temperatures are strongly associated with poor mental health and suicide in South Africa ( [[#Kim--2019|Kim et al., 2019]] ). Exposure to extreme heat directly influences emotional control, aggression and violent behaviour, escalating rates of interpersonal violence, with homicides rising by as much as 18% in South Africa when temperatures are above 30°C compared with temperatures below 20°C ( [[#Burke--2015a|Burke et al., 2015a]] ; [[#Chersich--2019b|Chersich et al., 2019b]] ; [[#Gates--2019|Gates et al., 2019]] ).

Extreme weather events are often severely detrimental to mental health ( [[#Scheerens--2020|Scheerens et al., 2020]] ), with elevated rates of anxiety, post-traumatic stress disorder and depression in impacted individuals ( [[#Schlenker--2010|Schlenker and Lobell, 2010]] ; [[#Nuvey--2020|Nuvey et al., 2020]] ). Youths may be at especially high risk ( [[#Barkin--2021|Barkin et al., 2021]] ).

Loss of livestock from disease or lack of pastures is strongly linked with poor mental health among farmers ( [[#Nuvey--2020|Nuvey et al., 2020]] ). Climate change impacts on mental health among refugees is concerning but remains under-researched ( [[#Matlin--2018|Matlin et al., 2018]] ).

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==== 9.10.2.7 Air Quality-related Health Impacts ====

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Links between air quality and climate change are complex ( [[#Smith--2014|Smith et al., 2014]] ; [[#Szopa--2021|Szopa et al., 2021]] ). Increases in particulate matter concentrations are driven more by vehicle emissions, solid waste, biomass burning and development ( [[#Abera--2021|Abera et al., 2021]] ) than by climate change, and these factors vary widely across regions of the continent ( [[#West--2013|West et al., 2013]] ). Women and children who are exposed to high particulate matter concentrations when cooking indoors and HIV-infected people are more vulnerable to the health impacts of air pollution ( [[#Abera--2021|Abera et al., 2021]] ). Information on the direction of change of air quality in different African regions attributable to climate change are contradictory ( [[#Westervelt--2016|Westervelt et al., 2016]] ; [[#Silva--2017|Silva et al., 2017]] ). Additionally, much uncertainty remains about interactions between air quality and climate change and relative impacts of different modes of development and climate change on pollutants. However, increasing temperatures combined with a reduction in rainfall are ''likely'' to increase particulate matter concentrations ( [[#Abera--2021|Abera et al., 2021]] ), particularly in north Africa ( [[#Westervelt--2016|Westervelt et al., 2016]] ; [[#Silva--2017|Silva et al., 2017]] ).

Nevertheless, continued dependence on fossil-fuelled power plants will result in tens of thousands of avoidable deaths due to air pollution by 2030 ( [[#Marais--2016|Marais and Wiedinmyer, 2016]] ), and accelerate climate change. Actions to reduce air pollution can both mitigate climate change and have major co-benefits for health ( [[#West--2013|West et al., 2013]] ; [[#Rao--2016|Rao et al., 2016]] ; [[#Markandya--2018|Markandya et al., 2018]] ; [[#Rauner--2020a|Rauner et al., 2020a]] ; [[#Rauner--2020b|Rauner et al., 2020b]] ) see also AR6 WGIII, Chapters 3, 4, 8 and 10). Investing in renewable energy resources rather than reliance on the combustion of fossil fuels would mark an important step forward for African population health ( [[#Marais--2019|Marais et al., 2019]] ). This is especially important in South Africa which emits approximately half the total carbon emissions for Africa, ranking 12th in the world for carbon emissions ( [[#Mohsin--2019|Mohsin et al., 2019]] ).

Dust events in west Africa have severe health impacts (cardiorespiratory and infectious diseases, including meningitis) ( [[#Ayanlade--2020|Ayanlade et al., 2020]] ) given the proximity of the Sahara, which produces about half of the yearly global mineral dust ( [[#de%20Longueville--2013|de Longueville et al., 2013]] ). Wildfires are projected to become the main source of particulate matter in west, central and southern Africa under both the lowest and highest future emissions scenarios, whereas, under intermediate scenarios (i.e., SSP3/RCP4.5), anthropogenic sources of particulate matter are projected to exceed that produced by wildfires ( [[#Knorr--2017|Knorr et al., 2017]] ).

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'''Box 9.6 | Pandemic risk in Africa: COVID-19 and future threats'''
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Rapid advances in vaccination and other control measures in high-income countries means that the burden of COVID-19 is increasingly concentrated in low- and middle-income countries, including those in Africa. The extent to which the COVID-19 pandemic is influenced by weather or by future changes in climate remains contested ( [[#WMO--2021|WMO, 2021]] ). In time, COVID-19 may develop seasonal dynamics ( [[#Baker--2020|Baker et al., 2020]] ; [[#Kissler--2020|Kissler et al., 2020]] ) similar to other respiratory infections ( [[#Carlson--2020b|Carlson et al., 2020b]] ).

Early work interpreted low-reported cases of COVID-19 in Africa as suggesting evidence of a protective climatic effect, but increasing evidence indicates the role of climate is secondary to the timing of disease introduction, the pace of implementation of non-pharmaceutical interventions and surveillance gaps ( [[#Evans--2020|Evans et al., 2020]] ; [[#WMO--2021|WMO, 2021]] ). Going forward, testing coverage, reporting, governance, non-pharmaceutical interventions and vaccine distribution and uptake are ''likely'' to be far more significant for Africa’s COVID-19 trajectory than climate change. Compounding risks, where climate hazards and natural disasters impair outbreak responses, may disrupt interventions or cause additional deaths ( [[#Phillips--2020|Phillips et al., 2020]] ; [[#Salas--2020|Salas et al., 2020]] ).

Emerging and future pandemic threats

Future influenza pandemics are highly ''likely'' , as are regional epidemics and pandemics of novel zoonotic viruses (including coronaviruses and flaviviruses) ( ''high confidence'' ). In the next decades, climate change will reshape the risk landscape for emerging zoonotic threats as wildlife-livestock-human interfaces shift, facilitating the emergence of novel zoonotic threats and spillover of known zoonoses into novel geographies ( [[#Carlson--2020a|Carlson et al., 2020a]] ; [[#Mordecai--2020|Mordecai et al., 2020]] ). Characteristics of urban development and level of service provision, for example, crowded living spaces and transport facilities, and access to water and sanitation will influence the transmission of COVID-19 and future disease outbreaks ( [[#Wilkinson--2020|Wilkinson, 2020]] ). Historically, west and central Africa were considered especially at risk of outbreaks given their high biodiversity, high intensity of human–wildlife contact including wild meat trade, vulnerable health systems and history of Ebola virus disease outbreaks ( [[#Paige--2014|Paige et al., 2014]] ; [[#Allen--2017|Allen et al., 2017]] ; [[#Pigott--2017|Pigott et al., 2017]] ). However, as the Middle East respiratory syndrome coronavirus (MERS-CoV) and COVID-19 pandemics have shown, there are multiple hotspots of viruses with pandemic potential globally, many of which are not in Africa. Thus, labelling African rainforests as unique ‘hotspots’ undermines global health work and pandemic preparedness.

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'''Box 9.7 | The health–climate change nexus in Africa'''
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The intersections between climate change and human health involve interactions of numerous systems and sectors (Lindley et al., 2019; Yokohata et al., 2019). This complexity means that holistic, transdisciplinary and cross-sectoral (systems) approaches like One Health, EcoHealth and Planetary Health can improve the long-term effectiveness of responses to health risks (Zinsstag, 2012; Whitmee et al., 2015; Nantima et al., 2019). More research is needed to identify sustainable solutions (Rother et al., 2020), as recently re-emphasised by the Intergovernmental Panel on Biodiversity in its report on the COVID-19 pandemic (IPBES, 2020). The close dependency of many Africans on their livestock and surrounding ecosystems forms a context where integrated health approaches are especially critical for addressing climate change risks to health (Figure Box 9.7.1; Watts et al., 2015; Cissé, 2019).

Integrated approaches to health in Africa can deliver multiple benefits for humans and ecosystems For example, rather than addressing micronutrient deficiencies with supplements, which may not be accepted culturally and can be disrupted by stockouts or similar, addressing nutrient deficiencies in staple crops by selecting or breeding more nutritious varieties (e.g., orange-fleshed sweet potatoes or ‘golden rice’ for vitamin A deficiency) may prove to be more sustainable options (Datta et al., 2003; Nair et al., 2016; Laurie et al., 2018; Oduor et al., 2019; Stokstad, 2019). Additionally, some micro- or macronutrient deficiencies and food insecurities may be improved by addressing the depletion of soils through better management, including the incorporation of holistic, sustainable principles, such as those promoted by agroforestry or regenerative agriculture (Rhodes, 2017; Elevitch et al., 2018; [[#LaCanne--2018|LaCanne and Lundgren, 2018]] ; Chapter 5 Section 5.12.4).

[[File:4cbbd13cb814b56b9422e27ff59021ef IPCC_AR6_WGII_Figure_9_Box_9_7_1.png]]

'''Figure Box 9.7.1 |''' ''' Human, ecosystem and animal health are intimately interlinked, and require transdisciplinary approaches such as One Health, EcoHealth and Planetary Health for effective, sustainable, long-term management.''' This schematic shows some examples of these interlinkages, and how they impact human health, highlighting the complex interactions and the importance of holistic, systems approaches to health interventions, including for climate change adaptation. Supporting literature: (1) (Egoh et al., 2012); (2) (Wangai et al., 2016); (3) (Failler et al., 2018); (4) (Ifejika Speranza, 2010); (5) (Brancalion et al., 2020); (6) (Bloomfield et al., 2020); (7) (Rojas-Downing et al., 2017).

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