Potential impacts of global warming on the wave climates of the western and southern coasts of southern Africa

• Main Author: Marshall, Cole James
• Other Authors: Theron, Andre Karl, Owen, Robyn, Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
• Format: Thesis
• Language: English
• Published: Stellenbosch : Stellenbosch University 2023
• Subjects: Global warming; Ocean waves > Climate > Africa; Southern; Climatic changes > Africa; Coastal engineering > Africa; Southern Ocean
• Online Access: http://hdl.handle.net/10019.1/126980

Thesis (MEng)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Southern Africa is a region which is exposed to a high energy wave climate generated far off shore in the Southern Ocean by very high wind speeds and extra-tropical storms found in the westerly belt in the mid to high-latitudes of the Southern Ocean (Theron et al., 2014). Here, the impacts of global warming on the wave climate of southern Africa are investigated under the IPCC specified warming scenarios of RCP4.5 and RCP8.5. Literature on the climatic drivers of southern African wave climate and the changes already observed in these systems, and literature on global-scale wave projection models is reviewed to establish a foundation for projecting future change in the study area. Using NCEP WaveWatch III and ERA5 reanalysis data from 1979 to 2021, a baseline wave climate at several locations along the coastline of the study region is established, and data analysis on the historical data is performed. Projections for the 2080-2100 end-of-century time slice are made from the projections present in the literature, and short-term projections are made based on trends found in the historic data. In the short-term, there is a projected increase in wave heights and periods at all seasons for both the mean and annual maxima wave parameters, with the winter wave climate showing the most significant increasing trend. There is also a trend of anti-clockwise rotation, especially in the summer months, in mean wave direction that is projected in the short term. In the long-term, this anticlockwise rotation is expected to continue, with up to a 4⁰ rotation expected at some locations by 2100. The long-term projections also show projected increases in winter wave heights and extreme wave heights, however, there are projected decreases for summer wave heights across nearly all locations. 100-year return period wave heights experience the most significant increase of 8% along the southern coast of South Africa. These changes are then contextualised from an ...