Rainfall Variability and Trends Analyses in Nigeria Using Remotely Sensed Data and CMIP5 Models

The complex rainfall patterns in Nigeria, with notable increases and declines, pose significant environmental risks and agricultural opportunities. Investigating their drivers and impacts is essential for understanding socio-economic and environmental dynamics. This research aims to analyse the spatial and temporal variability of rainfall patterns in Nigeria, identifying trends, potential impacts on agriculture, and the implications for climate change adaptation and sustainable development strategies in the region. Satellite-based precipitation data spanning from 1981 to 2019; and climate projection data from the Coupled Model Intercomparison Project Phase 5 (CMIP5), spanning the years 2020 to 2059 were employed. Statistical techniques such as the Coefficient of Variation (CV), Sen’s Slope estimator, and Mann–Kendall Trend Test were applied to assess precipitation variability and trends at both annual and seasonal scales, while rainfall variability and trend patterns were mapped using Kriging interpolation method in ArcGIS environment. The study revealed that annual precipitation across Nigeria was below 20%, reflecting less variability in inter-annual rainfall, while high variability (> 30%) occurred during March–May and September–November seasons in the northern part of the country, which makes the area vulnerable to drought. Increasing rainfall variability (2020–2059), especially in the north is also observed. The study further revealed a significant annual precipitation increase in Nigeria (1981–2019), with 94% of stations showing positive trends, mainly in the March–April-May and September–October-November seasons. Under RCP 8.5, significant rainfall decreases are expected, impacting water resources and agriculture, while RCPs 2.6 and 4.5 show non-significant trends. Urgent adaptation strategies like agricultural adaptation, water resource management, infrastructure development, capacity building, policy and planning, are essential in Nigeria to address climate risks like droughts in the north and floods in the south, promoting sustainable development and community resilience.