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

== 9.2 Key Risks for Africa ==

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A key risk is defined as a potentially severe risk. In line with AR5, ‘severity’ relates to dangerous anthropogenic interference with the climate system, the prevention of which is the ultimate objective of the United Nations Framework Convention on Climate Change (UNFCCC) as stated in its Article 2 ( [[#Oppenheimer--2014|Oppenheimer et al., 2014]] ). The process for identifying key risks for Africa included reviewing risks from [[#Niang--2014|Niang et al. (2014)]] and assessing new evidence on observed impacts and projected risks in this chapter.

Several key risks were identified for both ecosystems and people including species extinction and ecosystem disruption, loss of food production, reduced economic output and increased poverty, increased disease and loss of human life, increased water and energy insecurity, loss of natural and cultural heritage and compound extreme events harming human settlements and critical infrastructure (Table 9.2). In order to provide a sector- and continent-level perspective, the key risks aggregate across different regions and combine multiple risks within sectors. For detailed assessments of observed impacts and future risks within each sector and each sub-region of Africa, see the sector-specific sections of this chapter (Sections 9.6 to 9.12).

'''Table 9.2 |''' Key risks from climate change in Africa

{| class="wikitable"
|-
! Key climate change risk

! Climate impact driver

! Vulnerability

! Section

|-
| Local or global extinction of species and reduction or irreversible loss of ecosystems and their services, including freshwater, land and ocean ecosystems

| Increasing temperatures of freshwaters, ocean and on land; heatwaves; precipitation changes (both increases and decreases); increased atmospheric CO 2 concentrations; sea level rise; ocean acidification

| Vulnerability highest among poorly dispersing organisms (plants) and species with narrow and disappearing niches (e.g., mountain endemics), and is exacerbated by non-climate hazards (e.g., habitat loss for agriculture or afforestation projects); vulnerability is high for Protected Areas surrounded by transformed land preventing species’ dispersal and areas with limited elevational gradients that reduce their potential to act as climate refugia.

| 9.6

|-
| Risks to marine ecosystem health and to livelihoods in coastal communities

| marine heatwaves, increased acidification and sedimentation/turbidity

| low-income coastal communities (e.g., artisanal fisherfolk, fishmongers) whose livelihood depends on healthy coral reefs, seagrass beds and mangroves

| 9.6, 9.8

|-
| Loss of food production from crops, livestock and fisheries

| Increasing temperatures and heat waves for freshwaters, ocean and on land; precipitation changes; drought; increased atmospheric CO 2 concentrations

| High for low-income coastal and riparian communities whose livelihood depends on healthy ocean and freshwater ecosystems, and for populations reliant on fish for protein and micronutrients. Vulnerability is high for many food producers dependent on rainfall and temperature conditions, including subsistence farmers, the rural poor, and pastoralists. Lack of access to climate information and services increases vulnerability.

| 9.8

|-
| Mortality and morbidity from increased heat and infectious diseases (including vector-borne and diarrhoeal diseases)

| Increasing temperatures; heatwaves; precipitation change (both increases and decreases)

| Vulnerability is highest for the elderly, pregnant women, individuals with underlying conditions, immune-compromised individuals (e.g., from HIV) and young children.

Regions without vector control programmes in place or without detection and treatment regimens.

Inadequate insulation in housing in informal settlements in urban heat islands. Inadequate improvements in public health systems.

Inadequate water and sanitation infrastructure, especially in rapidly expanding urban areas and informal settlements.

| 9.10

|-
| Reduced economic output and growth, and increased inequality and poverty rates

| Increased temperatures; reduced rainfall; drought; extreme weather events

| Conditions underlying severe risk are lower income growth, higher population levels, low rates of structural economic change with more of the labour force engaged in agriculture and other more climate-exposed sectors due in part to physical labour outdoors.

| 9.11

|-
| Water and energy insecurity due to shortage of irrigation and hydropower

| Heat and drought

| High reliance on hydropower for national electricity generation, especially east and southern African countries. Planned for high reliance on irrigated food production. Concentrations of hydropower plants within river basins experiencing similar rainfall and runoff patterns. Limited electricity trade between major river basins.

| 9.7; 9.9; Box 9.5

|-
| Cascading and compounding risks of loss of life, livelihoods and infrastructure in human settlements

| Extreme heat; floods; drought; sea level rise and associated coastal hazards; compound climate hazards (e.g., coinciding heat and drought)

| Coastal and low-lying urban areas and those in dryland regions with rapidly growing populations. People living in informal settlements. Increased magnitude of heat waves due to urban heat island effects. Climate shocks to municipal revenues (e.g., from water). Unaffordable maintenance of transport and protective infrastructure with increasing climate impacts. Greater water resource demand from urban and non-urban populations and key economic sectors.

| 9.9

|}

Several expert elicitation workshops of lead and contributing authors were held to develop ‘burning embers’ assessing how risk increases with further global warming for a subset of key risks, specifically risk of food production losses, risk of biodiversity loss and risk of mortality and morbidity from heat and infectious disease (Figure 9.6). These key risks were selected in part because of underlying assessment work in the chapter to connect multiple studies to observed impacts and/or risk at increasing global warming levels (Sections 9.6.2; 9.8.2; 9.8.5.2; 9.10.2).

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'''Figure 9.6 |''' '''Risks increase with increasing levels of global warming, as shown by this Burning Embers figure for selected key risks from climate change in Africa.''' Increases in risk are assessed for the levels of global warming above pre-industrial (1850–1900). All three risks are assessed to have already transitioned to moderate risk by the recent level of global warming 2010–2020 (1.09°C). Risks are characterised as undetectable, moderate, high, or very high, and the transition between risk levels as a function of global warming is represented by the colour change of each bar ( [[#IPCC--2021|IPCC, 2021]] ). Vertical lines show the range of global warming for a change in the risk level. The dots indicate the confidence level for a given transition in risk and are placed at the level of global warming that is the assessed best estimate for that increase in the risk level. For the range of global warming levels for each risk transition used to make this figure see Supplementary Material Table SM 9.1.

All three of these key risks are assessed to have already transitioned completely into moderate risk—that is, negative impacts have been detected and attributed to climate change—before the 2010–2020 level of global warming (1.09°C) above pre-industrial times ( [[#IPCC--2021|IPCC, 2021]] ), with ''medium confidence'' for increased mortality and morbidity and ''high confidence'' for losses of food productivity and biodiversity (Figure 9.6). For biodiversity, these impacts include repeated mass die-offs of coral reefs due to marine heat ( [[#9.6.1.4|Section 9.6.1.4]] ), reductions in lake productivity due to warming ( [[#9.6.1.3|Section 9.6.1.3]] ), and woody encroachment of grasslands and savannas due to increased atmospheric CO 2 concentrations ( [[#9.6.1.1|Section 9.6.1.1]] ), with negative impacts on livelihoods ( [[#9.6.2|Section 9.6.2]] ). For food production, climate change impacts include up to 5.8% mean reduction in maize productivity due to increased temperatures in sub-Saharan Africa (Sections 9.8.2.1; 9.8.2.2) and reduced fisheries catches due to increased temperatures, especially in tropical regions ( [[#9.8.2|Section 9.8.2]] ). For health, climate change impacts include increased mortality and morbidity from changes in the distribution and incidence of malaria and cholera and the direct effects of increasing temperatures ( [[#9.10.2|Section 9.10.2]] ).

In scenarios with low adaptation (that is largely localised and incremental), the transition to high risk—widespread and severe impacts—has already begun at the current level of global warming for biodiversity loss ( ''high confidence'' ), and begins below 1.5°C global warming for both food production ( ''medium confidence'' ) and mortality and morbidity from heat and infectious disease ( ''high confidence'' ). Across all risks, the best estimate for the transition to high risk is at 1.5°C of global warming, with transition to high risk completing before 2°C (Figure 9.6). Projected impacts considered high risk around 1.5°C include: across more than 90% of Africa, more than 10% of species are at risk of local extinction (Figure 9.6; Table 9.1); the further expansion of woody plants into grass-dominated biomes ( [[#9.6.2.1|Section 9.6.2.1]] ); 9% declines in maize yield for west Africa and 20–60% decline in wheat yield for southern and northern Africa, as well as declines in coffee and tea in east Africa and sorghum in west Africa (Figures 9.22; 9.23; Sections 9.8.2.1; 9.8.2.2), and &gt;12% decline in marine fisheries catch potential for multiple west African countries, potentially leaving millions at risk of nutritional deficiencies (Figure 9.25; [[#9.8.5|Section 9.8.5]] ); tens of millions more people exposed to vector-borne diseases in east and southern Africa (malaria), and north, east and southern Africa (dengue, zika), increased risk of malnutrition in central, east and west Africa, and more than 15 additional deaths per 100,000 annually due to heat in parts of west, east and north Africa (Figures 9.32; 9.35; Sections 9.10.2; 9.9.4.1).

The transition from high to very high risk—that is severe and widespread impacts with limited ability to adapt—begins either at or just below 2°C for all three risks (Figure 9.6). The assessed temperature range for the transition to very high risk is wider for food production than for biodiversity and health. Projected impacts for food include: 10–30% decline in marine fisheries catch potential for the Horn of Africa region and southern Africa and more than 30% decline for west Africa at 2°C global warming, with greater declines at higher levels of warming ( [[#9.8.2|Section 9.8.2]] ). Beyond 2°C global warming, over 50% of commercially important freshwater fish species across Africa are projected to be vulnerable to extinction (Figure 9.26). Between 2°C and 4°C, wheat, maize and rice yields are projected, on average, to be lower than 2005 yields across all regions of Africa. From 2°C global warming, over 40% losses in rangeland productivity are projected for western Africa. By 3.75°C, severe heat stress may be near year-round for cattle across tropical Africa (Figure 9.24). Multiple countries in west, central and east Africa are projected to be at risk from simultaneous negative impacts on crops, fisheries and livestock (Sections 9.8.2; 9.8.5; [[#Thiault--2019|Thiault et al., 2019]] ).

The best estimate for the onset of very high risk for biodiversity and health is at 2.1°C. Projected impacts considered very high risk for biodiversity include potential destabilisation of the African tropical forest carbon sink, risk of local extinction of more than 50% of plants, vertebrate and insect species across one-fifth of Africa, 7–18% of African species at risk of total extinction including, a third of freshwater fish, and more than 90% warm-water coral reefs lost ( [[#9.6.2|Section 9.6.2]] ). For health, projected impacts considered high risk include potentially lethal heat exposure for more than 100 days per year in west, central and east Africa, with more than 50 additional heat-related deaths per 100,000 annually across large parts of Africa, and hundreds of millions more people exposed to extreme heat in cities ( [[#9.5|Section 9.5]] ; 9.10.2; 9.9.4.1; Figure 9.35), tens to hundreds of thousands of additional cases of diarrhoeal disease in east, central and west Africa, and tens of millions more people exposed to mosquito-borne arboviruses like dengue or zika in north, east and southern Africa ( [[#9.10.2|Section 9.10.2]] ).

The feasibility and effectiveness of existing adaptation options under current levels of warming are assessed in [[#9.10.2|Section 9.10.2]] and adaptation options considering future levels of warming are assessed in the chapter section for each sector.

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