Evaluation of desert encroachment and atmospheric warming southwards of Nigeria

Nigeria is located south of the Sahara and is confronted with rapid desertification, with severe impacts in northern Nigeria with signs of desert encroachment and atmospheric warming southward of Nigeria. Therefore, this study assessed the rate of desert encroachment and atmospheric warming southwards in Nigeria. The climate of Imo State was studied using Nigerian Meteorological Agency (NIMET)data. The climatic variables studied were annual rainfall, maximum and minimum annual temperatures. The mean temperature was computed from the temperature data. Data from the 30-year period from 1987 to 2016 were used. The annual rainfall and temperature data were divided into three decades, from 1987 to 1996, 1997 to 2006, and 2007 to 2016, to study the variation in decades. Mean monthly variations were also studied. Land features were also assessed. Desert encroachment was assessed in the study area using the criteria for the evaluation of desertification status proposed by the FAO/UNEP (1984). The results revealed that annual rainfall in Owerri was highest in the first decade, with a mean of 2,526.2 mm and the lowest in the third decade, with a mean of 2,278.66 mm. This shows a drop in annual rainfall as the years progressed. The results also reveal that the annual rainfall totals in Imo State are reducing by 13.50 mm annually, indicating desert encroachment as evidenced in loss of vegetation and erosion menace. According to the FAO/UNEP (1984) rating of desertification, desert encroachment in the study area is rated as ‘moderate.’ The maximum temperature shows a mean of 32 ^°C for the first decade, 32.5 ^°C for the second decade, and 32.5 ^°C for the third decade. The mean annual temperature of Owerri was found to increase by 0.02 ^° °C per annum. This shows the atmospheric warming of Imo State.