Modelling climate change impacts on selected indigenous crops in marginalised communities of South Africa.

Abstract

Climate projections indicate a drier and hotter environment for the Sub-Saharan Africa (SSA) region, including South Africa (SA), under different emission scenarios. These changes present climate and environmental risks which have multifaceted consequences on agri-food and water systems, socio-economic and ecological systems, livelihoods, and food and nutrition security, particularly for rural smallholder farming households. Under these circumstances, promoting locally adapted, multi-risk resilient, and nutrient-dense crops is touted as a plausible adaptation strategy. This thesis integrates results from various numerical models to conduct interdisciplinary research, highlighting the interconnected challenges of climate risk, food insecurity and resource management in SA. This work highlights the transformative potential of and gaps in the utility of neglected and underutilised crop species (NUS) through a systemic literature review (chapter 2) while exploring their potential to transform South African agri-food systems (chapters 2 and 5) for environmental sustainability and human health within safe planetary boundaries under climate change (chapter 3). For chapter 3, changes in rainfall [Climate Moisture Index (CMI)], and air temperature [Thermal Heat Index (THI)], across three time periods [the present (1961-1990), near future (2015-2044) and distant future (2070-2099)] are computed and assessed using an ensemble of six GCMs forced by RCP 8.5 in three Hydro-climatic zones (HCZs 1,2 & 5) in South Africa. Chapter 4 assesses the relationship between the climate risk coping strategies of smallholder farming households and food and nutrition security outcomes among households in rural areas, focusing on the three poorest provinces in South Africa. We provide a comparative analysis of the Nutritional Yields (NY) and Nutritional Water Productivity (NWP) of Mainstream and NUS crops across the three time periods in the 5th chapter. In this chapter, the AquaCrop Model was used to determine crop yields and water use efficiency for selected NUS and Mainstream crops across 5838 South African sub-catchments. The simulations covered the years 1960 to 2100, divided into three 30-year timelines. The overall findings of the study underscore the necessity for climate-informed, context-specific interventions and support systems to facilitate the adoption of appropriate, effective and scalable multi-risk adaptation strategies. Such strategies are essential for agri-food systems transformation and for strengthening their long-term climate resilience and sustainability, within a food- and nutrition-sensitive framework that prioritises social equity, ecological integrity, and planetary health.