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

=== 5.10.3 Projected Impacts ===

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The impacts of climate change on risk in mixed farming systems are projected to be dependent on market, ecosystem and policy context ( ''medium evidence'' , ''low agreement'' ). In mixed crop–livestock farms in a semi-arid region of Zimbabwe, Descheemaeker (2018) found that feeding forages and grain could alleviate dry-season feed gaps to the 2050s, but their effectiveness depended on the household’s livestock stocking density. In comparing different commercial production systems, Tibesigwa (2017) found that, under South African conditions, climate change to the 2050s will reduce productivity across the agricultural sector, with the largest impacts occurring in specialised commercial crop farms owing to their relative lack of diversity. Mixed farming systems were the least vulnerable in terms of relative effects on farm output; this applied to commercial and subsistence sectors ( [[#Tibesigwa--2017|Tibesigwa et al., 2017]] ). Other studies suggest increased risk in mixed systems in semi-arid conditions. In northern Burkina Faso, Rigolot (2017) examined different crop fertilisation and animal supplementation levels under RCP8.5 to the 2050s. They found that, although aggregate profits could be increased via moderate levels of inputs, the use of external inputs may increase risk because of marginal costs exceeding marginal benefits in lower rainfall years. In the Western Australian wheat belt, Thamo (2017) assessed climate-change-induced shifts in farm profitability to the 2050s. For most options, the adverse effects on profitability were greater than the advantageous effects, profit margins being much more sensitive to climate change than production levels. However, in the same system, Ghahramani (2018) evaluated adaptation options to 2030 and found that a shift to a greater reliance on livestock could be profitable, even in years with low rainfall.

Risk management in integrated production systems may constitute a barrier to uptake of adaptation options ( [[#Rigolot--2017|Rigolot et al., 2017]] ). Watson (2018) highlighted the current lack of financial risk management tools that could be used in smallholder coastal communities. Alongside other risk management tools such as weather-based index insurance, risk pooling may find wide application in different farming systems as an effective adaptation measure ( ''medium agreement'' , ''limited evidence'' ) ( [[#Hansen--2019a|Hansen et al., 2019a]] ).

Climate change impacts on productivity of agroforestry systems are similar to individual perennial crops, although there is limited research on tree crops (see [[#5.4.1.2|Section 5.4.1.2]] ). Impacts include increased temperature or water stress, an increase in pathogens affecting crops, changes to pollinator abundance, and changes in the nutrient content of one or more of the agroforestry components. Many tree products such as fruits and nuts are grown in agroforestry settings. The quality and nutrition of these products and other specialty crops are often negatively affected by rising temperatures, ambient CO 2 concentrations and tropospheric ozone ( [[#Ahmed--2016|Ahmed and Stepp, 2016]] ). There is also evidence that the fungus coffee rust will be positively affected by climate change ( [[#Avelino--2015|Avelino et al., 2015]] ; [[#Bebber--2016|Bebber et al., 2016]] ), with adverse effects on coffee agroforestry systems.

While shade trees can ameliorate increasing stand temperatures that will significantly impact arabica coffee ( [[#Ovalle-Rivera--2015|Ovalle-Rivera et al., 2015]] ; [[#Schroth--2015|Schroth et al., 2015]] ), the opposite can also be true. Comparing shade and full-sun coffee systems in Ghana, Abdulai (2018) concluded that the leguminous tree species providing shade and additional nitrogen led to soil water competition with the coffee trees during severe drought, resulting in enhanced coffee mortality. On the other hand, experimentally induced drought in a soybean-intercropping agroforestry system in eastern Canada led to crop losses in the monocropping system only, whereas N-fixation declined in both systems ( [[#Nasielski--2015|Nasielski et al., 2015]] ). Thus, balancing the synergies and trade-offs of multiple component systems is necessary based on local context. While species diversification can enhance resilience to climate shocks, lack of water can constrain the implementation of agroforestry practices in arid locations ( [[#Apuri--2018|Apuri et al., 2018]] ).

For people reliant on both agriculture and fisheries for food production, regional differences in productivity effects of climate change are expected; populations in LMICs that are already vulnerable will be most affected by simultaneous reductions in fisheries and agricultural productivity ( [[#Blanchard--2017|Blanchard et al., 2017]] ). Twelve out of 17 high-income countries in Europe showed projected increases in agricultural production where adaptive capacity is higher, and agricultural and food fisheries’ dependence was lower. Some LMIC countries (Nigeria, Cameroon, Ghana and Gabon) showed relative reductions in both fisheries and agricultural production, where food insecurity, human population growth and fisheries overexploitation rates are high ( [[#Blanchard--2017|Blanchard et al., 2017]] ). Model projections under the RCP6.0 scenario show decrease in marine and terrestrial production to 2050 in 87 out of the 119 coastal countries studied, even though there is a wide variance in adaptive capacity and relative and combined dependencies on fisheries and agriculture ( [[#Blanchard--2017|Blanchard et al., 2017]] ). A projected 2050 move towards greater consumption of cultured seafood and less meat showed that aquaculture requires less feed crops and land, but was regionally dependent upon differing patterns of production, trade and feed composition ( [[#Froehlich--2018b|Froehlich et al., 2018b]] ).

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'''Box 5.7: Perspectives of Crop and Livestock Farmers on Observed Changes in Climate in the Sahel'''
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The Sahel region of West Africa has experienced some of the most severe multi-decadal rainfall variations in the world: excessive rainfall in the 1950s–1960s followed by two decades of deficient rainfall, leading to a large negative trend until the mid-to-late 1980s with a decrease in annual rainfall of between 20% and 30%. Recently, there has been a partial recovery of annual rainfall amounts, more significant over the central than the western Sahel. This recovery is characterised by new rainfall features, including false starts and early cessation of rainy seasons, increased frequency of rainy days, increased precipitation intensity and more frequent and longer dry spells ( [[#Salack--2015|Salack et al., 2015]] ; [[#Sanogo--2015|Sanogo et al., 2015]] ; [[#Salack--2016|Salack et al., 2016]] ; [[#Biasutti--2019|Biasutti, 2019]] ). The Sahel is experiencing a new era of rainfall extremes ( [[#Bichet--2018|Bichet and Diedhiou, 2018]] ; [[#Panthou--2018|Panthou et al., 2018]] ), suggesting an intensification of the hydrological cycle ( [[#Doblas-Reyes--2021|Doblas-Reyes et al., 2021]] ).

The ways in which crop and livestock farmers in the Sahel have responded to climatic variability have been studied widely (Sissoko, 2011; [[#Gonzalez--2012|Gonzalez et al., 2012]] ; [[#Jalloh--2013|Jalloh et al., 2013]] ; [[#Gautier--2016|Gautier et al., 2016]] ; [[#Sultan--2016|Sultan and Gaetani, 2016]] ; [[#Zougmoré--2016|Zougmoré et al., 2016]] ; [[#Segnon--2019|Segnon, 2019]] ). Local communities have developed an extensive Indigenous ecological knowledge system, enabling them to make use of ecosystem services to support their livelihoods and to survive environmental change ( [[#Nyong--2007|Nyong et al., 2007]] ; [[#Mertz--2009|Mertz et al., 2009]] ; [[#Lahmar--2012|Lahmar et al., 2012]] ; [[#Segnon--2015|Segnon et al., 2015]] ). These knowledge systems have been crucial in people’s resilience to and recovery from major environmental change, such as the severe drought period experienced in the region in the 1970s and 1980s ( [[#Nyong--2007|Nyong et al., 2007]] ; [[#Lahmar--2012|Lahmar et al., 2012]] ; [[#Segnon--2015|Segnon et al., 2015]] ; [[#Gautier--2016|Gautier et al., 2016]] ; [[#Zouré--2019|Zouré et al., 2019]] ). As climate change became evident and a primary concern on the global agenda, interest in local people’s knowledge and understanding of climate change has also increased ( [[#Mertz--2009|Mertz et al., 2009]] ; [[#Tambo--2013|Tambo and Abdoulaye, 2013]] ; [[#Traore--2015|Traore et al., 2015]] ; [[#Kosmowski--2016|Kosmowski et al., 2016]] ; [[#Sanogo--2017|Sanogo et al., 2017]] ; [[#Segnon--2019|Segnon, 2019]] ).

There is no simple understanding of crop and livestock farmers’ response in the Sahel to rainfall variability. [[#Nielsen--2010|Nielsen and Reenberg (2010)]] developed human–environment timelines for the period 1950–2008 for a small village in northern Burkina Faso, relating livelihood diversification and crop–livestock management changes that map closely to local rainfall variability, such as fields abandoned in dry years and intense animal manure use in wet years. Although they found a significant correlation between crop–livestock management practice changes and major climatic events, the climate is only one of many interacting factors that influence local adaptation strategies ( [[#Mortimore--2010|Mortimore, 2010]] ; [[#Nielsen--2010|Nielsen and Reenberg, 2010]] ; [[#Sendzimir--2011|Sendzimir et al., 2011]] ). Robust attribution of observed changes to specific change drivers remains a challenge.

Crop and livestock farmers’ knowledge and perceptions of increases in temperature and temperature-related stressors (heatwaves, number of extreme hot or cold days) are consistent with the observed meteorological data ( [[#Mertz--2009|Mertz et al., 2009]] ; [[#Mertz--2012|Mertz, 2012]] ; [[#Tambo--2013|Tambo and Abdoulaye, 2013]] ; [[#Traore--2015|Traore et al., 2015]] ; [[#Sanogo--2017|Sanogo et al., 2017]] ; [[#Segnon--2019|Segnon, 2019]] ). Their perceptions of changes in rainfall amounts have not always been consistent with the observational record ( [[#Mertz--2012|Mertz, 2012]] ; [[#Segnon--2019|Segnon, 2019]] ). Nevertheless, their perception of increases in dry spell occurrence during the rainy season and changes in rainfall pattern (onset, cessation, intensity and distribution) were consistent with the recent observations ( [[#Barbier--2009|Barbier et al., 2009]] ; [[#Ouédraogo--2010|Ouédraogo et al., 2010]] ; [[#Tambo--2013|Tambo and Abdoulaye, 2013]] ; [[#Salack--2015|Salack et al., 2015]] ; [[#Traore--2015|Traore et al., 2015]] ; [[#Kosmowski--2016|Kosmowski et al., 2016]] ; [[#Salack--2016|Salack et al., 2016]] ; [[#Segnon--2019|Segnon, 2019]] ). Rainfall patterns within the season, rather than the total amounts of rainfall, matter more for crop and livestock farmers in the Sahel ( [[#Segnon--2019|Segnon, 2019]] ).

Crop and livestock farmers in the Sahel have a sophisticated understanding of the local climate. There is considerable potential to harness this knowledge, coupled with an enabling institutional environment, in developing policies and adaptation plans ( [[#Rasmussen--2018|Rasmussen et al., 2018]] ); the Sahel is a region where meteorological stations and observed data are scarce ( [[#Buytaert--2012|Buytaert et al., 2012]] ; [[#Nkiaka--2017|Nkiaka et al., 2017]] ). A deeper understanding of the resilience of local ecological knowledge systems, in light of the hydro-climatic intensification currently experienced in the region and future changes, may well provide further insights into their long-term effectiveness.

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