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

=== 9.8.3 Adapting to Climate Variability and Change in Agriculture ===

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Agricultural and livelihood diversification are strategies used by African households to cope with climate change, enabling them to spread risks and adjust to shifting climate conditions ( [[#Thierfelder--2017|Thierfelder et al., 2017]] ; [[#Thornton--2018|Thornton et al., 2018]] ). This includes adjusting cropping choices, planting times, or size, type and location of planted areas ( [[#Altieri--2015|Altieri et al., 2015]] ; [[#Nyagumbo--2017|Nyagumbo et al., 2017]] ; [[#Dayamba--2018|Dayamba et al., 2018]] ). In southern Africa, changes in planting dates provide farmers with greater yield stability in uncertain climate conditions ( [[#Nyagumbo--2017|Nyagumbo et al., 2017]] ). In Ghana, farmers are changing planting schedules and using early maturing varieties to cope with late-onset and early cessation of the rainy season ( [[#Antwi-Agyei--2014|Antwi-Agyei et al., 2014]] ; [[#Bawakyillenuo--2016|Bawakyillenuo et al., 2016]] ).

The use of drought-tolerant crop varieties is another adaptation available to African farmers ( [[#Hove--2018|Hove and Gweme, 2018]] ; [[#Choko--2019|Choko et al., 2019]] ). Adoption, however, is hindered by lack of information and training, availability or affordability of seed, inadequate labelling and packaging size for seed supplies and financial constraints ( [[#Fisher--2015|Fisher et al., 2015]] ). Moreover, drought-tolerant varieties do not address changing temperature regimes ( [[#Guan--2017|Guan et al., 2017]] ).

Crop diversification enhances crop productivity and resilience and reduces vulnerability in smallholder farming systems ( [[#McCord--2015|McCord et al., 2015]] ; [[#Mulwa--2020|Mulwa and Visser, 2020]] ). In Tanzania, diversified crop portfolios are associated with greater food security and dietary quality ( [[#Brüssow--2017|Brüssow et al., 2017]] ). In Kenya, levels of crop diversity are higher in villages affected by frequent droughts, which are the main cause of crop failure ( [[#Bozzola--2020|Bozzola and Smale, 2020]] ). Crop diversification also helps control pest outbreaks, which may become more frequent and severe under increased climate variability and extreme events ( [[#Schroth--2014|Schroth and Ruf, 2014]] ). High farming diversity enables households to better meet food needs, but only up to a certain level of diversity ( [[#Waha--2018|Waha et al., 2018]] ), and the viability of and benefits from mixed farming are highly context dependent ( [[#Thornton--2015|Thornton and Herrero, 2015]] ; [[#Weindl--2015|Weindl et al., 2015]] ).

Agroecological and conservation agriculture practices, such as intercropping, integration of legumes, mulching and incorporation of crop residues, are associated with household food security and improved health status ( [[#Nyantakyi-Frimpong--2017|Nyantakyi-Frimpong et al., 2017]] ; [[#Shikuku--2017|Shikuku et al., 2017]] ). These practices can enhance the benefits of other adaptations, such as planting drought- and heat-tolerant or improved varieties, although effects vary across soil types, geographical zones and social groups ( [[#Makate--2019|Makate et al., 2019]] ; [[#Mutenje--2019|Mutenje et al., 2019]] ). Non-climatic variables, such as financial resources, access to information and technology, level of education, land security and gender dynamics affect feasibility and adoption ( [[#Makate--2019|Makate et al., 2019]] ; [[#Mutenje--2019|Mutenje et al., 2019]] ).

To mitigate growing water stress, countries like Ethiopia, Rwanda, Tanzania and Uganda are striving to improve irrigation efficiency ( [[#McCarl--2015|McCarl et al., 2015]] ; [[#Connolly-Boutin--2016|Connolly-Boutin and Smit, 2016]] ; [[#Herrero--2016|Herrero et al., 2016]] ). The feasibility and effectiveness of this adaptation depend on biophysical and socioeconomic conditions ( [[#Amamou--2018|Amamou et al., 2018]] ; [[#Harmanny--2019|Harmanny and Malek, 2019]] ; [[#Schilling--2020|Schilling et al., 2020]] ). Irrigation is unaffordable for many smallholder farmers and only covers a negligible proportion of the total cultivated area. Nonetheless, in some regions of west Africa, small-scale irrigation, including the digging of ditches, holes and depressions to collect rainwater ( [[#Makondo--2018|Makondo and Thomas, 2018]] ), is widely adopted and promoted to support national food security ( [[#Dowd-Uribe--2018|Dowd-Uribe et al., 2018]] ).

African farmers are also diversifying their income sources to offset reduced yields or crop losses by shifting labour resources to off-farm work, or by migrating seasonally or longer term ( [[#Kangalawe--2017|Kangalawe et al., 2017]] ; [[#Hove--2018|Hove and Gweme, 2018]] ). Off-farm activities provide financial resources that rural households need to cope with extreme climate variability ( [[#Hamed--2018|Hamed et al., 2018]] ; [[#Rouabhi--2019|Rouabhi et al., 2019]] ). However, in some cases, these off-farm activities can be maladaptive at larger scales, such as when households turn to charcoal production, which contributes to deforestation ( [[#Egeru--2016|Egeru, 2016]] ). Whether off-farm activities constitute maladaptation depends on whether resources are available to upgrade skills or support investments that make a new business more lucrative. Without such resources, this option may lead to impoverishment (see Box 5.8).

Smallholder farmers’ responses tend to address short-term shocks or stresses by deploying coping responses (e.g., selling labour, reducing consumption and temporary migration), rather than longer-term sustainable adaptations ( [[#Ziervogel--2014|Ziervogel and Parnell, 2014]] ; [[#Jiri--2017|Jiri et al., 2017]] ). This is partly due to institutional barriers (e.g., markets, credit, infrastructure and information) and resource requirements that are unaffordable to smallholder farmers ( [[#Pauline--2017|Pauline et al., 2017]] ). There is a need for policies that strengthen natural, financial, human and social capitals, the latter being key to household and community resilience, especially where government services may be limited ( [[#Mutabazi--2015|Mutabazi et al., 2015]] ; [[#Alemayehu--2017|Alemayehu and Bewket, 2017]] ). There is evidence that collective action, local organisations and climate information are associated with higher food security, and that institutional interventions are needed to ensure scaling up of adaptations ( [[#Thornton--2018|Thornton et al., 2018]] ).

A range of options is considered potentially effective in reducing future climate change risk, including plant breeding, crop diversification alongside livestock, mixed planting, intercrops, crop rotation and integrated crop–livestock systems (see [[IPCC:Wg2:Chapter:Chapter-5|Chapter 5]] Sections 5.4.4; 5.14.1; [[#Thornton--2014|Thornton and Herrero, 2014]] ; [[#Cunningham--2015|Cunningham et al., 2015]] ; [[#Himanen--2016|Himanen et al., 2016]] ; [[#Farrell--2018|Farrell et al., 2018]] ; [[#Snowdon--2021|Snowdon et al., 2021]] ). However, adaptation limits for crops in Africa are increasingly reached for global warming above 2°C ( ''high confidence'' ), and in tropical Africa may already be reached at current levels of global warming ( ''low confidence'' ).

Global warming beyond 2°C will place nearly all of sub-Saharan Africa cropland substantially outside of its historical safe climate zone ( [[#Kummu--2021|Kummu et al., 2021]] ) and may exponentially increase the cost of adaptation and residual damage for major crops ( [[#Iizumi--2020|Iizumi et al., 2020]] ). Without accounting for CO 2 increases, global-scale studies employing ensembles of gridded crop models for 2°C of global warming find that for adaptation using genetic cultivar change in most of Africa net losses are projected, even with adaptation up to 2°C of global warming for rice, maize, soybean and wheat ( [[#Minoli--2019|Minoli et al., 2019]] ; [[#Zabel--2021|Zabel et al., 2021]] ), although model uncertainty is still high ( [[#Müller--2021|Müller et al., 2021]] ). In contrast, when accounting for CO 2 increases, applying new genetics for rice under warming is projected to fully counteract all climate change-induced losses in Africa up to 3.5°C of global warming, except in west Africa ( [[#van%20Oort--2018|van Oort and Zwart, 2018]] ).

However, compared to temperate regions, risks of adaptation shortfalls—that is climate change impacts even after adaptation—are generally greater for current agricultural conditions across much of Africa (tropical, arid and semi-arid) ( [[#Sun--2019|Sun et al., 2019]] ). The overall adaptation potential to offset yield losses across Africa for rice, maize and wheat reduces with increasing global warming. On average, in projections including adaptation options, yield losses, in the median case, are reduced from −33% to −10% of 2005 levels at 2°C of global warming and from −46% to −23% at 4°C, but estimates vary widely (Figure 9.22; [[#Hasegawa--2021|Hasegawa et al., 2021]] ). Across Africa, the risks of no available genetic varieties of maize for growing season adaptation are higher for east Africa and southern Africa than for central or west Africa ( [[#Zabel--2021|Zabel et al., 2021]] ). To keep pace with expected rates of climate change, crop breeding, development and adoption must accelerate to meet the challenge ( [[#Challinor--2016|Challinor et al., 2016]] ). Regional modelling has shown very little efficacy for late sowing, intensification of seeding density and fertilizers, water harvesting and other measures for cereals in west Africa at 2°C of global warming ( [[#Sultan--2016|Sultan and Gaetani, 2016]] ; [[#Guan--2017|Guan et al., 2017]] ). Historical climate change adaptation by crop migration has been shown in some cases ( [[#Sloat--2020|Sloat et al., 2020]] ) but poses risks to biodiversity and water resources, and this option may be limited for maize in Africa by suitable climate shifting completely across national borders and available land at the edges of the continent ( [[#Franke--2021|Franke et al., 2021]] ). More research is required to evaluate the potential effectiveness and limits of adaptation options in African agriculture under future climate change (see [[IPCC:Wg2:Chapter:Chapter-5|Chapter 5]] [[IPCC:Wg2:Chapter:Chapter-5#5.4.4|Section 5.4.4]] for more details).

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