Exploring extreme warm temperature trends in South Africa: 1960–2016

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.