Assessing the impacts of climate change on climatic extremes in the Congo River Basin (original) (raw)
Related papers
Water
This study characterizes the future changes in extreme rainfall and air temperature in the Mono river basin where the main economic activity is weather dependent and local populations are highly vulnerable to natural hazards, including flood inundations. Daily precipitation and temperature from observational datasets and Regional Climate Models (RCMs) output from REMO, RegCM, HadRM3, and RCA were used to analyze climatic variations in space and time, and fit a GEV model to investigate the extreme rainfalls and their return periods. The results indicate that the realism of the simulated climate in this domain is mainly controlled by the choice of the RCMs. These RCMs projected a 1 to 1.5 °C temperature increase by 2050 while the projected trends for cumulated precipitation are null or very moderate and diverge among models. Contrasting results were obtained for the intense rainfall events, with RegCM and HadRM3 pointing to a significant increase in the intensity of extreme rainfall e...
Proceedings of the International Association of Hydrological Sciences, 2020
This study assessed the extreme rainfall and temperature changes over Mono river basin by the end of 21st century under the highest greenhouse gas emission scenario RCP8.5. Simulations of eight regional climate models (RCMs) provided by Africa-CORDEX program were considered. The maximum and minimum temperatures and rainfall were analyzed. Two groups of indices were analyzed. The first group consists of frequency indices: maximum number of consecutive dry days and wet days. The second group is intensity indices: fiveday maximum rainfall and simple daily intensity index. These variables were calculated at annual and seasonal scales. Changes from the baseline period 1971-2000 were computed for far future 2071-2100. As result, almost all the RCMs considered predicted a decrease of the rainfall and increase of maximum and minimum temperatures over most parts of the Mono basin, particularly in the south. Declining mean monthly precipitation and irregular rainy seasons at all scales were exhibited by most of the models. Simple daily intensity and five-day maximum rainfall are projected to decrease by the majority of the used models. As for dry and wet sequences, the RCMs showed an increase of the consecutive dry days and a decrease of wet days.
Atmosphere, 2013
We investigate the reasons for the opposite climate change signals in precipitation between the regional climate model REMO and its driving earth system model MPI-ESM over the greater Congo region. Three REMO simulations following three RCP scenarios (RCP 2.6, RCP 4.5 and RCP 8.5) are conducted, and it is found that the opposite signals, with REMO showing a decrease and MPI-ESM an increase in the future precipitation, diverge strongly as we move from a less extreme to a more extreme scenario. It has been shown that REMO simulates a much higher number of extreme rainfall events than MPI-ESM. This results in higher surface runoff and thus less soil infiltration, which leads to lower amounts of soil moisture in REMO. This further leads to less moisture recycling via evapotranspiration, which in turn results in less precipitation over the region. In the presence of a strong radiative forcing, the hydrological cycle becomes less intense in REMO and a downward trend in hydrological variables is observed. Contrary to this, the higher amounts of soil-moisture due to the lack of extreme rainfall events in MPI-ESM enhance the hydrological cycle. In the presence of strong radiative forcing, higher amounts of soil moisture result in increased evapotranspiration which in turn results in the higher amount of precipitation. It is concluded that the land-atmosphere coupling over the Congo region is very sensitive to the change in soil moisture amounts, which is likely to play a major role in global warming conditions. Therefore, adequate and improved representation of soil processes in climate models is essential to study the effects of climate change. However, the better representation of extreme rainfall events in REMO compared to
Trends and projections of climate extremes in the Black Volta River Basin in West Africa
Theoretical and Applied Climatology
This study used the RClimDex software to examine trends in extreme air temperature and rainfall in the Black Volta River Basin (BVRB) for the present (1981-2010) and future 2051-2080 (late twenty-first century) horizons. The analysis of the future extreme events was conducted using data output of four ensemble models for two IPCC emission scenarios, Representative Concentration Pathways (RCPs) 4.5 and 8.5. A bias correction method, the quantile-quantile (Q-Q) transformation technique, was applied to all the modelled temperature and rainfall data set prior to the index calculation. The results of analysis of the present-day climate indicate warming and wetting of the BVRB. Increasing trends were seen in the extreme warm indices while the extreme cold indices showed mostly decreasing trends. Majority of the trends observed in the indices were statistically significant (95% confidence level). The extremes in rainfall also showed increasing trends in amounts and intensity of rainfall events (majority of increasing trends were statistically insignificant). Projected temperatures for the late twenty-first century showed decreasing and increasing trends in the cold and warm indices respectively, suggesting warming during the period. Trend analysis of future rainfall projections mostly showed a mix of positive and negative trends offering no clear indication of the direction of change in majority of the extreme rainfall indices. An increase in extremely wet day events is however projected for the period. The results from this study could inform climate change adaptation strategies targeted at reducing vulnerability and building resilience to extreme weather events in the BVRB.
Modelling climatic trends for the Zambezi and Orange River Basins: implications on water security
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 Africandomain 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.
This paper performs non-parametric Mann Kendall (MK) trend analysis of historical hydroclimatic data (1961-2016), an ensemble climate model validation and a computation of 16 Expert Team on Climate Change Detection and Indices (ETCCDI) temperature and rainfall extremes indices. The climate indices are evaluated using MK test and annual trend analysis for two Representative Concentration Pathways (RCP4.5 & RCP8.5) future scenarios from 2020 to 2045 over Mono River Basin (MRB) in Togo. The annual and seasonal trend analyses are assessed on historical potential evapotranspiration, mean temperature, rainfall and discharge data. Results show positive and negative trends of hydroclimatic data over MRB from1961 to 2016. Mean temperatures increase significantly in most of the stations while a negative non-significant trend is noticed for rainfall. Meanwhile, the discharge presents a significant seasonal and annual trend for three gauge stations (Corrokope, Nangbéto and Athiémé). Validation ...
Analysis of temperature and rainfall trends in Beni City, Democratic Republic of Congo
Proceedings of the Indian Academy of Sciences. Earth and planetary sciences/Journal of earth system science, 2024
Understanding local-scale climate change is vital to developing adaptive strategies in the face of the century-old river of global warming posing a threat to humanity. This study focuses on assessing temperature and rainfall trends in Beni City, using monthly and yearly (1990-2020) weather station data. Climate variability was analysed using the standardised variable index, and rainfall concentration patterns were highlighted using the precipitation concentration index (PCI). The climate trends were analysed by using the Mann-Kendall test and Sen's slope estimator. The Bndings indicated that the T min is 18.82±0.62°C, and T max is 28.22±0.75°C, resulting in a mean temperature of 23.52±0.57°C. The annual and seasonal temperature trend analysis indicated that a significant warming trend was observed in both T min and T max. Beni City's precipitation trends also showed a mean annual rainfall of 1988.38±416.59 mm, with significant year-to-year variations. Annual rainfall analysis exhibited a slight upward trend; meanwhile, the seasonal trend analysis revealed an increase in rainfall during Mar-Apr-May (MAM) and Aug-Sep-Oct-Nov (ASON) seasons with roughly no discernible trend during Dec-Jan-Feb (DJF), and Jun-Jul (JJ) seasons. Overall, annual and seasonal analyses of speciBc temperature and rainfall patterns have shown pronounced warming and increased rainfall in the study area.
Congo Basin rainfall climatology: can we believe the climate models?
Philosophical Transactions of the Royal Society B: Biological Sciences, 2013
The Congo Basin is one of three key convective regions on the planet which, during the transition seasons, dominates global tropical rainfall. There is little agreement as to the distribution and quantity of rainfall across the basin with datasets differing by an order of magnitude in some seasons. The location of maximum rainfall is in the far eastern sector of the basin in some datasets but the far western edge of the basin in others during March to May. There is no consistent pattern to this rainfall distribution in satellite or model datasets. Resolving these differences is difficult without ground-based data. Moisture flux nevertheless emerges as a useful variable with which to study these differences. Climate models with weak (strong) or even divergent moisture flux over the basin are dry (wet). The paper suggests an approach, via a targeted field campaign, for generating useful climate information with which to confront rainfall products and climate models.
Theoretical and Applied Climatology, 2020
This study analyzes projected changes in seasonal extreme precipitation intensity and dry spell length in the investigation area (Côte d'Ivoire) under RCP4.5 and RCP8.5 forcing scenarios. To this end, a multi-model ensemble of fourteen CORDEX-Africa regional climate model simulations is used during the three stages of the West African Monsoon (WAM) season (April-June (AMJ), July-September (JAS), and October-December (OND)). The results indicate that Côte d'Ivoire is subject to a robust increase of cumulative intensity of precipitation associated with an amplification of extreme precipitation events during the WAM. In particular during JAS, a substantial increase in extreme precipitation reaching up to 50-60% compared to the reference mean value prevails in the western and coastal areas in the far future and under the RCP8.5 scenario. In addition, AMJ season is dominated by an increase in dry spell length of about 12% and 17% in the near future and 20% and 30% in the far future in the entire country under RCP4.5 and RCP8.5 scenarios, respectively, albeit considerable uncertainties. OND considered as the post-monsoon season is mostly characterized by a robust decrease in dry spell length more marked in the southwest in the RCP8.5 scenario during the far future. These results suggest that agricultural production and particularly cocoa plantations in the southwestern regions could be at the risk of flooding events and that water stress remains a threat for cocoa, coffee, and other cash crop plantations in the eastern regions.