keywords: Indicators, rainfall, maximum air temperature & relative humidity, climate change
This work identified, analyzed and interpreted some statistical indicators of climate change in Oyo, Nigeria. Data on daily rainfall amount (mm), maximum air temperature (oC) and maximum relative humidity (%) for Oyo metropolis was sourced from the International Institute of Tropical Agriculture (IITA), Ibadan and used in the study. The data span a period of 34 years (1977-2010). The statistical indicators indentified include; significant difference in the distribution of wet and dry days for each month over the period, increasing number of dry days and decreasing number of wet days over the period. Additional indicators identified include; significant difference in the distribution of warmer and colder maximum air temperature for each month over the period, increasing number of warmer days and decreasing number of colder days over the period. The last set of indicators include significant difference in the distribution of high and low relative humidity for each month over the period, increasing number of high relative humidity days and decreasing number of low relative humidity days over the period. One of the statistical methods employed in analyzing the indicators include; Kruskal-Wallis one-way analysis of variance test for ascertaining significant differences in the distribution of wet and dry days, distribution of warmer and colder maximum air temperature and the distribution of high and low relative humidity for each month over the period. The linear trend analysis was another method used in identifying the presence of increasing or decreasing trend in the distribution of the number dry and wet days, the number of warmer and colder maximum air temperature days and in the distribution of high and low relative humidity days. The study concludes that with these indicators, climate change is fast setting into Oyo metropolis, Nigeria and finally recommends that the best way to communicate the presence of climate change is through the use of indicators.
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