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

==== 9.8.5.2 Projected Risks of Climate Change to Fisheries ====

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At 4.3°C global warming, maximum catch potential (MCP) from marine fisheries in African Exclusive Economic Zones (EEZs) would decrease by 12–69% by the end of the 21st century relative to recent decades (1986–2005), whereas global warming of 1.6°C would limit the MCP decrease to 3–41% ( [[#Cheung%20William--2016|Cheung William et al., 2016]] ; [[#IPCC--2019c|IPCC, 2019c]] ). By mid-century under 2°C global warming, MCP would decrease by 10 to &gt;30% on the western coast of South Africa, the Horn of Africa and west Africa, indicating these regions could be at risk to declines in MCP earlier in the century than other parts of Africa ( [[#Cheung--2016|Cheung et al., 2016]] ). Declining fish harvests due to sea temperature rise could leave 1.2–70 (median 11.1) million people in Africa vulnerable to deficiencies in iron, and up to 188 million to vitamin A and 285 million to vitamin B 12 and omega-3 fatty acids by mid-century under 1.7°C global warming ( [[#Golden--2016|Golden et al., 2016]] ). [[#Maire--2021|Maire et al. (2021)]] assessed the nutritional vulnerabilities of African countries to climate change and overfishing, and found that the four most vulnerable countries ranked on a scale from 0 (low vulnerability) to 100 (high vulnerability) were Mozambique (87), Madagascar (76), Tanzania (61) and Sierra Leone (58). Coral reef habitat in east Africa is projected to decrease, resulting in negative impacts on demersal fish stocks and invertebrates ( [[#Hoegh-Guldberg--2018|Hoegh-Guldberg et al., 2018]] ). Central, west and east Africa are projected to be at the greatest nutritional risk from sea temperature rise, leading to reduced catch in coastal waters (Figure 9.25; [[#Golden--2016|Golden et al., 2016]] ). In north Africa, a rise in water temperatures is expected to impact the phenology and migratory patterns of large pelagic species (e.g., bluefin tuna, ''Thunnus thynnus'' ) ( [[#Hidalgo--2018|Hidalgo et al., 2018]] ). Increased sea surface temperatures have been associated with increases in spring and summer upwelling intensity reducing the abundance and larval survival of small pelagic fishes and shellfish in west Africa ( [[#Bakun--2015|Bakun et al., 2015]] ; [[#Tiedemann--2017|Tiedemann et al., 2017]] ; [[#Atindana--2020|Atindana et al., 2020]] ). Ocean warming, acidification and hypoxia are predicted to affect the early life history stages of several marine food species, including fish and crustaceans ( [[#Kifani--2018|Kifani et al., 2018]] ). Climate warming is projected to impact water temperature and horizontal and vertical mixing on the southern Benguela ecosystem, with marked negative effects on the biomass of several important fishery resources by 2050 amplified under 2.5°C compared to 1.7°C global warming ( [[#Ortega-Cisneros--2018|Ortega-Cisneros et al., 2018]] ).

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[[File:dd7f7df3b9c3499f3c2fa8ab68a87c41 IPCC_AR6_WGII_Figure_9_025.png]]

'''Figure 9.25 |''' '''Climate change increases risks to the catch potential and nutrition from marine fisheries.'''

'''(a)''' The percentage of animal source foods consumed that originate from a marine environment. Countries with higher dependence are indicated by darker shades of green ( [[#Golden--2016|Golden et al., 2016]] ).

'''(b–c)''' Projected percentage change in maximum catch potential of marine fisheries compared to the recent past (1986–2005) under 1.6°C global warming and &gt;4°C global warming by end of 21st century (2081–2100) in countries’ Exclusive Economic Zones (EEZs) ( [[#Cheung%20William--2016|Cheung William et al., 2016]] ). Darker red indicates greater percentage reduction (negative values).

'''(d–e)''' Countries (in purple) that have overlap between high nutritional dependence on marine fisheries and high risk of reduction in maximum catch potential under the two global warming scenarios. Global warming levels were calculated using a baseline for pre-industrial global mean temperature of 1850–1900.

For inland fisheries, 55–68% of commercially harvested fish species will be vulnerable to extinction under 2.5°C global warming by the end of the 21st century (2071–2100) compared to 77–97% under 4.4°C global warming (Figure 9.26). This will increase the number of countries that are at food security risk due to fishery species declines from 10 to 13 (Figure 9.26). Other recent analyses suggest that African countries with the highest inland fisheries production have low- to mid-range projected climate risk (2.4°C–2.6°C local temperature increase compared to other regions with 2.7°C–3.3°C increase by end of century) based on a 3.9°C global warming scenario ( [[#Harrod--2018b|Harrod et al., 2018b]] ). In regions where inland fishery production is derived primarily from lakes, there is a lower likelihood of reduced catch, especially where precipitation is projected to increase (e.g., African Great Lakes region) ( [[#Harrod--2018b|Harrod et al., 2018b]] ). Regions reliant on rivers and floodplains (e.g., Zambezi and Niger basins) are more ''likely'' to experience downturns in catch, as hydrological dynamics may be altered ( [[#Harrod--2018b|Harrod et al., 2018b]] ). Projections suggest that opportunistic species that do well in modified systems ( [[#Escalera-vázquez--2017|Escalera-vázquez et al., 2017]] ) and small pelagic fishes will remain important components of inland fishery food systems ( [[#Kolding--2016|Kolding et al., 2016]] ; [[#Gownaris--2018|Gownaris et al., 2018]] ; 2019). Climate adaptation responses that rely on freshwater resources (e.g., hydroelectric power generation, agricultural irrigation) represent threats to inland fisheries ( [[#Cowx--2018|Cowx et al., 2018]] ; [[#Harrod--2018c|Harrod et al., 2018c]] ), by changing flow regimes, reducing water levels, and increasing runoff of pesticides and nutrients ( [[#Harrod--2018c|Harrod et al., 2018c]] ).

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[[File:16a1a5a6a362d2da1a05b2693b7ca404 IPCC_AR6_WGII_Figure_9_026.png]]

'''Figure 9.26 |''' '''Climate change risk to''' '''freshwater fisheries.'''

'''(a)''' Countries’ dependence on inland fisheries for nutrition; darker green shows higher dependence on inland fisheries.

'''(b–c)''' Projected numbers of freshwater fishery species vulnerable to climate change within freshwater ecoregions under &gt;2°C global warming and &gt;4°C global warming estimated by the end of the 21st century (2071 to 2100). Numbers of vulnerable fish species translate to an average of 55–68% vulnerable at &gt;2°C and 77–97% vulnerable at &gt;4°C global warming. Darker reds indicate higher concentrations of vulnerable fish species.

'''(d–e)''' Countries (in purple) that have an overlap between high dependence on freshwater fish and high concentrations of fishery species that are vulnerable to climate change under two warming scenarios. Countries’ dependence on inland fisheries for nutrition was estimated by catch (total, tonnes) ( [[#FAO--2018b|FAO, 2018b]] ; [[#Fluet-Chouinard--2018|Fluet-Chouinard et al., 2018]] ), per capita catch (kg per person per year) ( [[#FAO--2018b|FAO, 2018b]] ), percentage reliance on fish for micronutrients, and percentage consumption per household ( [[#Golden--2016|Golden et al., 2016]] ). Z-scores of each metric were averaged for each country to create a composite index describing ‘current dependence on freshwater fish’ for each country with darker blue colours indicating higher dependence. Data on vulnerable fish species was from ( [[#Nyboer--2019|Nyboer et al., 2019]] ).

For both marine and freshwater fisheries, climate-related extreme weather events and flooding may drive the loss of fishing days, cause damage and loss to fishing gear, endanger the lives of fishers and block transportation from damaged roads ( [[#Muringai--2021|Muringai et al., 2021]] ). Fish processing via weather-dependent techniques such as sun drying may be hampered, causing post-harvest losses ( [[#Akintola--2017|Akintola and Fakoya, 2017]] ; [[#Chan--2019|Chan et al., 2019]] ).

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