Abstract/Description
Extreme temperatures driven by global warming pose significant challenges to ecosystems, infrastructure, and human activities in worldwide, particularly in regions such as Central Africa, which exhibits low resilience and limited capacity for adaptation and mitigation. The present study examines the performance of the RegCM4 model in reproducing extreme temperatures in Central Africa during the 2002-2006 period, considered as the control period, and evaluates the variations in the near future under the emission scenarios RCP2.6, RCP4.5, and RCP8.5. The study uses six extreme temperature indices based on the recommendations of the Expert Team on Climate Change Detection and Indices (ETCCDI). These include four intensity indices and two duration indices. Special attention has been given to two sub-regions integrated into the study area for more specific analysis. The first sub-region, named Zone 1, is semi-arid, while the second, named Zone 2, is humid. In the context of our projections, particular attention has also been given to a third sub-region, named Zone 3.
We found that regardless of the region or season, RegCM4 performs quite well in simulating intensity indices related to daily minimum temperatures (TNn and TNx), with underestimations not exceeding 4°C. For intensity indices based on daily maximum temperatures (TXx and TXn), warm biases can reach 10°C, attributed to the model’s limitations in representing solar and surface thermal fluxes. While warm sequences are overestimated, cold sequences are better captured. Statistical evaluations confirm RegCM4’s suitability for studying extreme temperatures, particularly for TNn, TNx, and cold sequences (CSDI), which were prioritized in projections.
Future projections indicate a widespread increase in intensity indices, especially in northern regions, while Zones 2 and 3 experience a milder effect. Under RCP8.5, extreme warming surpasses 30°C in several areas. Compared to 1985-2004, biases suggest moderate changes under RCP4.5 (1-2°C) but significant shifts under RCP2.6 and RCP8.5 (2-3.5°C). Cold nights are expected to become rare, with hot nights increasing. The CSDI results predict a sharp decline in cold sequences, potentially disappearing under RCP2.6 and RCP8.5. However, under RCP4.5, cold sequences may persist, with gaps reaching 40 days regionally and up to 80 days in Zone 1.