Abstract
Warm extreme temperature events or ‘heatwaves’ have disastrous impacts. Several high-impact heatwave events have recently occurred in the Global North, resulting in significant losses of human life and dire effects on economies. The expected increases in the frequency and intensity of extreme heat events under climate change pose a significant threat to South Africa. South Africa, a developing country, with an increasing population, faces many socioeconomic challenges. This study presents the first comprehensive annual and seasonal, spatial and temporal trend analyses of daily maximum and minimum extreme temperature events recorded from 20 meteorological stations across South Africa, spanning 1960–2016. Trend results based on the World Meteorological Organization Expert Team on Climate Change Detection (ETCCDI) and the World Meteorological Organization Commission for Climatology and Indices Expert Team on Sector-Specific Climate Indices (ET-SCI). Indices describing the characteristics of warm extremes are calculated using RClimDex and ClimPACT, respectively. The non-parametric Mann-Kendall test, Spearman rank correlation coefficient and Sen’s slope estimates were used to determine the statistical significance and magnitude of the calculated trend. Results show a general annual trend increase in maximum temperature at a rate of 0.02 °C year−1. The majority of stations reveals statistically significant trends in warm days and nights; with the strongest, general annual trend increases experienced in warm days at a rate of 0.15% year−1. Seasonally, the strongest increases of 0.11% days year−1 in warm days are evident for autumn, while increases of 0.07% days year−1 are calculated for summer. A general increasing trend in heatwave events is recorded at 0.03 events year−1 countrywide.
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Acknowledgements
We acknowledge the financial and collegial support offered to Adriaan J van der Walt from the Faculty of the Natural and Agricultural Sciences and the Geography Department at the University of the Free State. Jenner M Fitchett received funding from the DST-NRF Centre of Excellence for Palaeoscience. The authors thank Professor Christopher Curtis for suggestions and advice on earlier stages of the project. The authors would also like to thank Yang Feng for assistance with the download and usage of RClimDex and RHtestV4 software.
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JF receives operational support funding from the DSI-NRF Centre of Excellence for Palaeosciences.
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JF conceptualized and lead the project and was the principal supervisor. AvdW collected, curated and analysed the data and wrote the first draft. AvdW and JF developed the methodology, conducted the validation and wrote and revised the manuscript.
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van der Walt, A.J., Fitchett, J.M. Exploring extreme warm temperature trends in South Africa: 1960–2016. Theor Appl Climatol 143, 1341–1360 (2021). https://doi.org/10.1007/s00704-020-03479-8
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DOI: https://doi.org/10.1007/s00704-020-03479-8