Climate Variability in Temperature Trends and Change Point in Yenagoa, Nigeria

Abstract

This study aims to analyse temperature trend, variation, and change point patterns in Bayelsa State, Nigeria over a 31-year period (1992-2022). The daily temperature data used for the study were obtained from the Nigerian Meteorological Agency (NIMET). The daily maximum and minimum temperature data were further processed to obtain the annual maximum, minimum, and mean temperatures. Several statistical tests were utilized to investigate the temperature trend and to detect change point year. Linear regression and Mann-Kendall tests were employed to establish if there are significant trend in the temperature data series. Distribution-free CUSUM test and Sequential Mann-Kendall test were used to identify the change point year. The results reveal a statistically significant increasing trend in annual mean temperature at a rate of 0.020°C per year (0.2°C per decade or 2.0°C per century). Annual maximum temperature showed a marginally significant positive trend of 0.037°C per year, while annual minimum temperature exhibited a non-significant negative trend of -0.043°C per year. Change point analysis identified significant shifts in annual mean temperature patterns around 2007 and 2015. The findings indicate that Bayelsa State is experiencing warming consistently with global climate change patterns. However, cooler temperature is still experienced during the early hours and evening session as not significant increasing trend was observed in the annual minimum temperature.