ABSTRACT
A major challenge currently facing the world isclimate change andclimatevariability. In the Coastal Region of Nigeria, research interest had been on its impact. The degree of variability and the magnitudes of climate change which are crucial for planning adaptation and mitigation measures in the region need to be studied. This study which analyses climate variability and climate change in the Coastal Region of Nigeriais aimed at filling the identified research gap.
Climate Research Unit (CRU 0.5×0.5) gridded monthly climatic data for two climatic periods (1956-1986 and 1987-2016) were obtained.They were validated with data obtained from the Nigerian Meteorological Agency (NiMet). CRU data from 254 locations innin estates of the region were tested for normality, homogeneity, auto correlation, heteroscedasticity with the aid of XLSTAT Software to evaluate their properties. Tests for trend detection included: Mann-Kendal, Spearman’s Rho, and Linear Regression. Thei-Sen Slope test was used to determine the magnitude of the trend analysis. The cumulative sum, Cumulative Deviation, and Likelihood tests were used for Rainfall abrupt change detection. RankSumand Student's t-test were used to check for differences between Mean sof two Climatic periods. Periodicities were determined by spectral analysis and Climatic maps for rainfall and temperature from 1956 to 2016 for the coastal regions of Nigeria were developed by ordinary kriging.
The results of the study indicate the existence of climate variability and climate change in the region depicted by declining rainfall, rising temperature, and abrupt climatic changes in the region during the period 1956 to 2016. This was mainly from 1976-1985 decade with 1980 the most probable year of abrupt change. The Hottest months of the years were in February and March while the coldest months were in August in alllocations in the study area. The wettest decade was 2006-2015 with an average rainfall change of 69.8 (mm/decade). The most probable year was2012whenNigeria experienceda high level of flooding. The driest decade was 1976-1985 with amean rainfall change of 17.45 (mm/decade). The hottest decade was 1976-1985 with amean temperature change of 0.1348 (°C/decade). The coolest decade was 1996-2005 with a mean temperature change of 0.022 (°C/decade). There was very high rainfall variability with the coefficient of variability (CV) values ranging between 62.43% and 69.46% and low-temperature variability with the CV values ranging between 4.314% and 6.037%. Period ogram plots revealed significant periodicity for rainfall and temperature of between 15 years and 20 years. The results of this study revealed the urgent need for mitigation and adaptation measures to be putin place by policy makers to combat anticipated impacts of climate change variability so as to raise awareness of the risks of declining water quantity and quality, energy and food security, flooding and coastal erosion. The development of techniques and technologies for early warning signals, good adaptation programmes, and mitigation projects can greatly reduce these risks. Themaps produced are useful guides to water engineers as well as other persons involved in the use of climatic data for development in order to attain the United Nations Sustainable Development Goals.
