Editing IPCC:AR6/SRCCL/Chapter-5 (section)

==== 5.3.2.3 Role of agroecology and diversification ====

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Agroecological systems are integrated land-use systems that maintain species diversity in a range of productive niches. Diversified cropping systems and practicing traditional agroecosystems of crop production where a wide range of crop varieties are grown in various spatial and temporal arrangements, are less vulnerable to catastrophic loss (Zhu et al. 2011 <sup>[[#fn:r502|502]]</sup> ). The use of local genetic diversity, soil organic matter enhancement, multiple-cropping or poly-culture systems, home gardening, and agroecological approaches can build resilience against extreme climate events (Altieri and Koohafkan 2008 <sup>[[#fn:r503|503]]</sup> ).

However, Nie et al. (2016) <sup>[[#fn:r504|504]]</sup> argued that while integrated crop-livestock systems present some opportunities such as control of weeds, pests and diseases, and environmental benefits, there are some challenges, including yield reduction, difficulty in pasture-cropping, grazing, and groundcover maintenance in high rainfall zones, and development of persistent weeds and pests.

Adaptation measures based on agroecology entail enhancement of agrobiodiversity; improvement of ecological processes and delivery of ecosystem services. They also entail strengthening of local communities and recognition of the role and value of ILK. Such practices can enhance the sustainability and resilience of agricultural systems by buffering climate extremes, reducing degradation of soils, and reversing unsustainable use of resources; outbreak of pests and diseases and consequently increase yield without damaging biodiversity. Increasing and conserving biological diversity such as soil microorganisms can promote high crop yields and sustain the environment (Schmitz et al. 2015 <sup>[[#fn:r505|505]]</sup> ; Bhattacharyya et al. 2016 <sup>[[#fn:r506|506]]</sup> ; Garibaldi et al. 2017 <sup>[[#fn:r507|507]]</sup> ).

Diversification of many components of the food system is a key element for increasing performance and efficiency that may translate into increased resilience and reduced risks (integrated land management systems, agrobiodiversity, ILK, local food systems, dietary diversity, the sustainable use of indigenous fruits, neglected and underutilised crops as a food source) ( ''medium confidence'' ) (Makate et al. 2016 <sup>[[#fn:r508|508]]</sup> ; Lin 2011 <sup>[[#fn:r509|509]]</sup> ; Awodoyin et al. 2015 <sup>[[#fn:r510|510]]</sup> ).

The more diverse the food systems are, the more resilient they are in enhancing food security in the face of biotic and abiotic stresses. Diverse production systems are important for providing regulatory ecosystem services such as nutrient cycling, carbon sequestration, soil erosion control, reduction of GHG emissions and control of hydrological processes (Chivenge et al. 2015 <sup>[[#fn:r511|511]]</sup> ). Further options for adapting to change in both mean climate and extreme events are livelihood diversification (Michael 2017 <sup>[[#fn:r512|512]]</sup> ; Ford et al. 2015 <sup>[[#fn:r513|513]]</sup> ), and production diversity (Sibhatu et al. 2015 <sup>[[#fn:r514|514]]</sup> ).

Crop diversification, maintaining local genetic diversity, animal integration, soil organic matter management, water conservation, and harvesting the role of microbial assemblages. These types of farm management significantly affect communities in soil, plant structure, and crop growth in terms of number, type, and abundance of species (Morrison-Whittle et al. 2017 <sup>[[#fn:r515|515]]</sup> ). Complementary strategies towards sustainable agriculture (ecological intensification, strengthening existing diverse farming systems and investment in ecological infrastructure) also address important drivers of pollinator decline (IPBES 2016 <sup>[[#fn:r516|516]]</sup> ).

Evidence also shows that, together with other factors, on-farm agricultural diversity can translate into dietary diversity at the farm level and beyond (Pimbert and Lemke 2018 <sup>[[#fn:r517|517]]</sup> ; Kumar et al. 2015 <sup>[[#fn:r518|518]]</sup> ; Sibhatu et al. 2015 <sup>[[#fn:r519|519]]</sup> ). Dietary diversity is important but not enough as an adaptation option, but results in positive health outcomes by increasing the variety of healthy products in people’s diets and reducing exposure to unhealthy environments.

Locally developed seeds and the concept of seed sovereignty can both help protect local agrobiodiversity and can often be more climate resilient than generic commercial varieties (Wattnem 2016 <sup>[[#fn:r520|520]]</sup> ; Coomes et al. 2015 <sup>[[#fn:r521|521]]</sup> ; van Niekerk and Wynberg 2017; Vasconcelos et al. 2013 <sup>[[#fn:r522|522]]</sup> ). Seed exchange networks and banks protect local agrobiodiversity and landraces, and can provide crucial lifelines when crop harvests fail (Coomes et al. 2015 <sup>[[#fn:r523|523]]</sup> ; van Niekerk and Wynberg 2017 <sup>[[#fn:r524|524]]</sup> ; Vasconcelos et al. 2013 <sup>[[#fn:r525|525]]</sup> ).

Related to locally developed seeds, neglected and underutilised species (NUS) can play a key role in increasing dietary diversity (high confidence) (Baldermann et al. 2016 <sup>[[#fn:r526|526]]</sup> ; van der Merwe et al. 2016 <sup>[[#fn:r527|527]]</sup> ; Kahane et al. 2013 <sup>[[#fn:r528|528]]</sup> ; Muhanji et al. 2011 <sup>[[#fn:r529|529]]</sup> ) (Box 5.3). These species can also improve nutritional and economic security of excluded social groups, such as tribals (Nandal and Bhardwaj 2014 <sup>[[#fn:r530|530]]</sup> ; Ghosh-Jerath et al. 2015 <sup>[[#fn:r531|531]]</sup> ), indigent (Kucich and Wicht 2016 <sup>[[#fn:r532|532]]</sup> ) or rural populations (Ngadze et al. 2017 <sup>[[#fn:r533|533]]</sup> ).

Dietary diversity has also been correlated ( ''medium evidence, medium agreement'' ) to agricultural diversity in small-holder and subsistence farms (Ayenew et al. 2018 <sup>[[#fn:r534|534]]</sup> ; Jones et al. 2014 <sup>[[#fn:r535|535]]</sup> ; Jones 2017 <sup>[[#fn:r536|536]]</sup> ; Pimbert and Lemke 2018 <sup>[[#fn:r537|537]]</sup> ), including both crops and animals, and has been proposed as a strategy to reduce micronutrient malnutrition in developing countries (Tontisirin et al. 2002 <sup>[[#fn:r538|538]]</sup> ). In this regard, the capacity of subsistence farming to supply essential nutrients in reasonable balance to the people dependent on them has been considered as a means of overcoming their nutrient limitations in sound agronomic and sustainable ways (Graham et al. 2007 <sup>[[#fn:r539|539]]</sup> ).

'''Ecosystem-based adaptation (EbA)''' . EbA is a set of nature-based methods addressing climate change adaptation and food security by strengthening and conserving natural functions, goods and services that benefit people. EbA approaches to address food security provide co-benefits such as contributions to health and improved diet, sustainable land management, economic revenue and water security. EbA practices can reduce GHG emissions and increase carbon storage (USAID 2017 <sup>[[#fn:r540|540]]</sup> ).

For example, agroforestry systems can contribute to improving food productivity while enhancing biodiversity conservation, ecological balance and restoration under changing climate conditions (Mbow et al. 2014a <sup>[[#fn:r541|541]]</sup> ; Paudela et al. 2017 <sup>[[#fn:r542|542]]</sup> ; Newaj et al. 2016 <sup>[[#fn:r543|543]]</sup> ; Altieri et al. 2015 <sup>[[#fn:r544|544]]</sup> ). Agroforestry systems have been shown to reduce erosion through their canopy cover and their contribution to the micro-climate and erosion control (Sida et al. 2018 <sup>[[#fn:r545|545]]</sup> ). Adoption of conservation farming practices such as removing weeds from and dredging irrigation canals, draining and levelling land, and using organic fertilisation were among the popular conservation practices in small-scale paddy rice farming community of northern Iran (Ashoori and Sadegh 2016 <sup>[[#fn:r546|546]]</sup> ).

Adaptation potential of ecologically-intensive systems includes also forests and river ecosystems, where improved resource management such as soil conservation, water cycling and agrobiodiversity support the function of food production affected by severe climate change (Muthee et al. 2017 <sup>[[#fn:r547|547]]</sup> ). The use of non-crop plant resources in agroecosystems (permaculture, perennial polyculture) can improve ecosystem conservation and may lead to increased crop productivity (Balzan et al. 2016 <sup>[[#fn:r548|548]]</sup> ; Crews et al. 2018 <sup>[[#fn:r549|549]]</sup> ; Toensmeier 2016 <sup>[[#fn:r550|550]]</sup> ).

In summary, increasing the resilience of the food system through agroecology and diversification is an effective way to achieve climate change adaptation (robust evidence, high agreement). Diversification in the food system is a key adaptation strategy to reduce risks (e.g., implementation of integrated production systems at landscape scales, broad-based genetic resources, and heterogeneous diets) ( ''medium confidence'' ).

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