Abstract
Abstract Climate change impacts are dependent on changes in air temperature, rainfall (frequency and amount) and climate indices, which are highly certain. Climate extreme indices are important metrics that are used to communicate the impacts of climate change. The CORDEX African-domain RCM (SMHI-RCA4) run by seven CMIP5 (CCCma-CanESM2, IPSL-IPSL-CM5A-MR, MIROC-MIROC5, MPI-M-MPI-ESM-LR, NCC-NorESM1-M, MOHC-HadGEM2-ES and NOAA-GFDL-GFDL-ESM2M) and two representative concentration pathways (RCP4.5 and RCP8.5) were used in this study. The future climate change is analysed relative to 2020–2050/1970–2000 using a multi-model ensemble projection. Selected climate indices were analysed using a multi-model ensemble of CMIP5 GCMs (GFDL-ESM2G, HadGEM2-ES and IPSL-CM5A-MR). The climate data operators (CDOs) were used in merging and manipulating the modelled (RCM) data and ETCCDI climate indices. The Mann–Kendall was used to compute the trends in time-series data at p < 0.05. Results indicate that temperature will increase in the Orange and Zambezi River Basins. Rainfall shows variability in both river basins. The temperature-based indices (tn90pETCCDI, tnnETCCDI, tnxETCCDI, tx90pETCCDI, txnETCCDI and txxETCCDI) were statistically significant with positive linear trends. The dtrETCCDI and wsdiETCCDI were statistically significant with positive linear trends within the Zambezi River Basin. csdiETCCDI and tn10pETCCDI were statistically significant with negative trends in both basins. The change in rainfall, temperature and climate indices will have implications on agricultural production, provisions of various ecosystem services, human health, water resources, hydrology, water security, water quality and quantity. The climate extreme indices can assist in analysing regional and global extremes in meteorological parameters and assist climate, and crop modellers and policymakers in assessing sectoral impacts.
Highlights
Climate change is an important environmental issue (Javadinejad et al 2020) and is defines as a significant shift in the state of climate identified using statistical assessments by changes in either the mean state of the climate or in its variability, persisting over a long period of time (Intergovernmental Panel on Climate Model (IPCC 2007)
Once a riverine ecosystem is affected, the impacts will be felt through the hydrological regimes within the ecosystem but will affect human activities that depend on the water resources
Several other consequences are likely to follow if the dynamics of these riverine systems were to change due to climate change
Summary
Climate change is an important environmental issue (Javadinejad et al 2020) and is defines as a significant shift in the state of climate identified using statistical assessments by changes in either the mean state of the climate or in its variability, persisting over a long period of time (Intergovernmental Panel on Climate Model (IPCC 2007). Once a riverine ecosystem is affected, the impacts will be felt through the hydrological regimes within the ecosystem but will affect human activities that depend on the water resources. This is in addition to the threats to the survival of aquatic systems, wildlife and all organisms dependent on river systems. These riverine systems support wetlands, riparian areas and flood plains within their course, all of which would be affected by the impacts of climate change. Lack of integrated drought and flood management, low adaptive capacity, variability and uneven distribution of rainfall are expected to be amplified in future due to changes in precipitation and temperature (UNFCCC 2007; SADC-WD/ZRA 2008; Chisanga 2019; Chisanga et al 2020a)
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