Merging historical data records with MPI-ESM-LR and CanESM2 scenarios to assess long-term climate trends for the Massili Basin in central Burkina Faso

English Abstract:

Burkina Faso is facing tremendous challenges for its water and agricultural sector considering extreme droughts and floods which increased during the previous decades and given IPCC climate projections for West Africa. Addressing the lack of knowledge on past, present and future climate trends at local and regional scale in central Burkina Faso, this paper assesses trends in rainfall as well as minimum (TMIN) and maximum (TMAX) temperature from 1971 to 2100 in the Massili basin (2612 km²). Hence, a 50 years record (1961-2011) from Gonse station as well as data from two Regional Climate Models (MPI-M-MPI-ESM-LR and CCCma-CanESM2) were analyzed. The model data were extracted from the Coordinated Regional Climate Downscaling Experiment (CORDEX) data archive and included historical runs (1971-2005) and two representative concentration pathways scenarios (RCP4.5 and RCP8.5) for the period 2006-2100, all at 50*50 km²spatial resolution. The analysis of the simulation data and their comparison with the observed record indicate that both models reproduce the climate trend in the basin sufficiently. However, a bias correction was done using the observed data to improve the model data. The MPI-ESM-LR data predict an increase of TMIN by 1.8 ° C (RCP4.5) and 3.0 °C (RCP8.5)from 1971 to 2100, while TMAX increased by 1.8°C (RCP4.5) and 2.7°C (RCP8.5).The CanESM2 data however refer to an increase of TMIN by 2.2°C(RCP4.5) and 3.5°C (RCP8.5) as well as of TMAX and1.9°C (RCP4.5)and2.9 °C (RCP8.5). With an increase of 7.5 mm (RCP4.5) and a decrease of 14.8 mm (RCP4.5) until 2100, both rainfall scenarios from MPI-ESM-LR provide contradictory estimates. The CanESM2 data however refer to an increase of TMIN by 2.24°C (RCP4.5) and 3.48°C (RCP8.5) as well as of TMAX from 1.89°C (RCP4.5) to 2.9 °C (RCP8.5). In contrast, both CanESM2 scenarios show an increase of rainfall by 39 mm (RCP4.5) and 73.5mm (RCP8.5). The study showed that linking historic climate data with RCM projections are suitable assessing long-term climatic trends and, therewith, providing the required knowledge to develop climate adaptation strategies in Burkina Faso.