Projected Temperature and Precipitation Changes in Brazzaville, Republic of Congo: A CMIP6-Based Analysis

Climate change is a key driver of climatic instability and hydroclimatic extremes, particularly in regions like Brazzaville, in the Republic of Congo, where rising mean surface temperatures and increasing precipitation variability pose critical risks to water resources, agriculture, and urban infrastructure. Despite advances in global climate modelling (GCM), the lack of high-resolution and regional-specific projections limits data-driven adaptation strategies, hindering climate resilience planning. This study aims to assess future temperature and precipitation changes in Brazzaville using CMIP6 climate projections across different time scales: historical time (1981–2010), mid-century time (2031–2060), and late-century time (2071–2100). The study employs climate modelling and statistical analysis, utilizing CMIP6 projections from the ACCESS-CM2 model under the SSP2-4.5 scenario. Climate data were processed using MATLAB, incorporating bias correction (quantile mapping), statistical downscaling (CORDEX methods), trend analysis, and correlation assessments. Key climate indicators, including temperature and precipitation, were evaluated using mean, median, and standard deviation. Results show a statistically significant warming trend, with mean temperatures projected to increase by 3.5°C (± 0.2°C) between 2071 and 2100 compared to the historical baseline. Monthly mean temperatures may exceed 32.1°C during peak heat events, with seasonal anomalies suggesting an increase in extreme heat events beyond the 95th percentile. Precipitation projections show a + 6.8% increase in peak wet season rainfall, while dry season precipitation is projected to decline by − 10.3%, worsening seasonal contrasts. The probability of extreme precipitation events (> 90 mm/day) increases by 14.7%, showing a higher risk of flooding and runoff intensification. Meanwhile, consecutive dry days (CDDs) in the dry season are expected to increase by + 8 days per year, heightening drought severity and soil moisture deficits. Future microclimate is expected to undergo significant variability due to global climate change.