Abstract
Climate change is real, likewise its impacts, which cannot disappear on its own, unless we urgently act about it. The scenario currently constitutes the major environmental problem facing mankind in this century, with some serious repercussions on man and his environment. The unprecedented changes in the pattern of some of its elements (Temperature and Rainfall) in recent decades is alarming. This study analyzed trends and variability in air temperature as evidence of climate change in Zaria, Kaduna state, Nigeria. Monthly and annual Temperature data for 40 years (1979 – 2018) were sourced from Nigeria Meteorological Agency (NIMET), Zaria station and used for the study. Both descriptive (mean, standard deviation and coefficient of variability) as well as inferential statistics (Mann-Kendall trend test and Sen’s slope estimator, Cramer’s test and Student’s t-test (paired samples) were employed in analyzing the data, using appropriate software packages. For the monthly minimum temperature series, the result revealed the highest variability in December series (18.38%), while January had the most variable maximum and average temperature (8.60% and 7.46% respectively) over the period. The result also revealed significant positive trends in 10 of the monthly minimum, whole of the monthly maximum and six of the monthly average as well as the annual minimum, maximum and average temperature over the period. The highest total increase for the minimum temperature over the period was in June series (+2.40C) at 0.060C year-1, while for the maximum was in January and June series (4.00C each) at 0.100C year-1. However, for the average, it March and December series (1.60C each) at 0.040C year-1. Result for the annual series revealed a total increase of 1.20C, 2.80C and 2.00C for the minimum, maximum and average temperature over the 40-year period. Variation detected in the data series (Cramer’s test) through various sub-periodical windows shows that, the last sub-period (2009 – 2018) was significantly warmer than the beginning sub-periods (1979 – 1988) at α=0.05. While comparison of the sub-periods (Student’s t-test paired samples) shows more of significant positive difference between beginning and the last sub-periods, but significant negative between the beginning and middle sub-periods at α=0.05. However, if the trend detected in the data series persist, the annual minimum, maximum and average temperature would increase by 2.430C, 5.70C and 4.050C respectively, by the end of the present century. Therefore, the study concluded that, temperature of Zaria significantly rises, with a lot of variability over the last 40-years, indicating gradual shift to a new climatic normal, with possible impacts on socioeconomic wellbeing of the people. Thus, the study recommended that, further studies should be conducted on the socio-economic effects of the rising temperature in the study area; relevant agencies (both state and federal) should take the findings of this study as useful in coming up with policies and programs for managing the socio-economic impacts of the rise in temperature among other things; and more synoptic weather stations should be established in the study area, to have more spatial coverage of weather data record, which could be useful for further studies.
Key-Words / Index Term
Temperature, Trends, Variability, Mann-Kendall Trend Test, Sen’s Slope, Cramer’s Test, Zaria
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