Tanzania CMIP5 climate change projections

Abstract

This paper presents updated climate change projections for Tanzania based on Coupled Model Intercomparison Project phase 5 (CMIP5) using Mid-Century Representative Concentration Pathway (RCP) 8.5. A total of twenty global circulation models (GCMs) were downscaled based on the eleven Tanzania climatological zones using thirteen synoptic weather stations. For each climatological zone, the skill score test of the 20 GCMs was done against the observed rainfall and the threshold of 80% except for one zone, which used threshold of 75%, to select GCMs for projecting future rainfall and temperature. It was found that in all the climatological zones the number of GCMs which performed above the threshold ranged between five and twelve. Rainfall and temperature of skilled GCMs were then down-scaled by Delta method and then evaluated for uncertainty. The skill score test showed that climatological zones in the western part of Tanzania had higher skills and higher agreement compared to zones located in the eastern side. Stations in the bimodal rainfall zones such as Musoma and Same showed high level of uncertainty in the projected future rainfall and temperature. Temperature uncertainty was ± 0.4oC for Same, Musoma and Dodoma stations followed by Songea and Mbeya at ± 0.3oC. On average, temperature was projected to increase by about 0.9oC and also rainfall to increase but mainly in the month of April in the central and southern zones.