Global Change Institute Monthly Lunch-time Seminar

Dr Auther Maviza will present on the Historical and projected summer rainfall onset changes using high resolution kilometre-scale (k-scale) climate data.

Historical and projected summer rainfall onset changes using high resolution kilometre-scale (k-scale) climate data over South Africa. Current climate research indicates that the onset of South Africa’s primary summer rainy season is likely to be delayed under future climate scenarios. Such a shift would have profound societal and ecological consequences, requiring significant updates to the scientific guidance provided to government bodies and agricultural stakeholders. Under the Methods to Enhance Capability in High-resolution information for AdaptatioN (MECHANICS) project, this study evaluates the utility of kilometre-scale (k-scale) climate data in the analysis of rainfall onset alongside existing evidence. While rainfall onset definitions vary globally to accommodate diverse climatic zones, this study adopts the agrometeorological index of Tadross and Hewitson (2003). This index has been widely used in South Africa and was selected for its specific focus on crop-water requirements and its compatibility with the Climate Projections for Africa (CP4A) dataset. We introduce the k-scale data and present preliminary findings on the spatial dynamics of annual and monthly climatologies, comparing historical (1997–2007) and future (2095–2105) rainfall onset days across South Africa’s summer rainfall region (srr). Finally, we discuss ongoing work comparing the k-scale rainfall onset outputs with the coarse-resolution ERA5 and CMIP6 Global Climate Model (GCM) projections, to determine if the k-scale data improves the detection of shifts in rainfall onsets days over South Africa’s srr. Results have potential implications on future climate adaptation strategies in the country’s agricultural sector.

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