Observed trends and projections of temperature and precipitation in the Olifants River Catchment in South Africa

Abstract

Among the projected effects of climate change, water resources are at the center of the matrix. Certainly, the southern African climate is changing, consequently, localized studies are needed to determine the magnitude of anticipated changes for effective adaptation. Utilizing historical observation data over the Olifants River Catchment, we examined trends in temperature and rainfall for the period 1976–2019. In addition, future climate change projections under the RCP 4.5 and RCP 8.5 scenarios for two time periods of 2036–2065 (near future) and 2066–2095 (far future) were analysed using an ensemble of eight regional climate model (RCA4) simulations of the CORDEX Africa initiative. A modified Mann-Kendall test was used to determine trends and the statistical significance of annual and seasonal rainfall and temperature. The characteristics of extreme dry conditions were assessed by computing the Standardized Precipitation Index (SPI). The results suggest that the catchment has witnessed an increase in temperatures and an overall decline in rainfall, although no significant changes have been detected in the distribution of rainfall over time. Furthermore, the surface temperature is expected to rise significantly, continuing a trend already evident in historical developments. The results further indicate that the minimum temperatures over the Catchment are getting warmer than the maximum temperatures. Seasonally, the minimum temperature warms more frequently in the summer season from December to February (DJF) and the spring season from September to November (SON) than in the winter season from June to August (JJA) and in the autumn season from March to May (MAM). The results of the SPI affirm the persistent drought conditions over the Catchment. In the context of the current global warming, this study provides an insight into the changing characteristics of temperatures and rainfall in a local context. The information in this study can provide policymakers with useful information to help them make informed decisions regarding the Olifants River Catchment and its resources.

Unveiling Deviations from IPCC Temperature Projections through Bayesian Downscaling and Assessment of CMIP6 General Circulation Models in a Climate-Vulnerable Region

“…Recent studies warn that, in this state, 1980-2019 air temperatures have increased by about 0.01 • C per year (0.008-0.017 • C) [26]. Similar annual change magnitudes have also been detected in South Africa or Australia [27][28][29]. However, the region of the globe where the Mediterranean climate reaches its maximum extent is in the European Mediterranean Basin [22].…”

Time Series Analysis of Temperature and Rainfall in the Savannah Region in Togo, West Africa

“…According to the IPCC (2007) [1], the temperature in Africa is predicted to increase by 1.5 to 3 • C by 2050. Malhi and Wright (2004) [2] discovered that African tropical forests and South Africa will get warmer by 0.29 • C. Adeola et al (2022) [3], using a modified Mann-Kendall test on historical observation data from the period 1976-2019, found that the Olifants River Catchment in South Africa experienced an increase in temperature and an overall decline in rainfall, although no significant changes were detected in the distribution of rainfall time. Hulme et al (2005) [4] stated that rainfall in Africa has both spatial and temporal variability: in West Africa since the late 1960s, rainfall has been decreasing (Nicholson and Selato, 2000;Chappell and Agnew 2004;Dai et al, 2004) [5][6][7] while the Guinean coast recorded a 10% increase in annual rainfall between 1995 and 2005.…”