A new perspective on projected precipitation changes in Tanzania

Informed decision-making on adaptation strategies for future climate change need reliable climate information. In particular, vulnerable economies like Tanzania, which is strongly reliant on rain-fed agriculture, struggle with the lack of agreement on precipitation changes between the climate models. In order to find robustness in these projections, we compare precipitation simulations from the CORDEX Africa Ensemble under three emission scenarios (RCP 2.6, RCP 4.5, RCP 8.5) within different precipitation categories defined by the Standardized Precipitation Index (SPI). We find that despite the disagreement on the sign of the total precipitation trend, there is strong agreement among on a decrease in normal conditions and an increase in both extreme wet and extreme dry conditions throughout the 21st century. The differences between the projections in terms of total precipitation are related to shifts of (near) normal conditions to wetter conditions in the case of ‘wetter’ projections and to drier conditions for ’drier’ projections. These results indicate an overall broadening of the rainfall distribution especially toward extremely wet conditions.