ANALYSIS OF CLIMATE CHANGE FOR DROUGHT PROJECTION OVER SUDANO-SAHELIAN NIGERIA

Abstract

The study is aimed at analyzing climate change as it relates to drought and to make projections for future occurrences for better adaptation in the Sudano-Sahelian region of Nigeria. The specific objectives were to: evaluate the performance of regional climate model results for rainfall with the observed surface data over the region for present climate; assess anticipated climatic changes that may occur in the region, and Produce a drought severity map for the present and future climate regimes. Monthly surface observed rainfall data of six selected synoptic stations in the region for the period of (1980-2010) and a Swedish Meteorological and Hydrological Institute (SMHI) regional climate model (RCM) data were used for the same period. Drought projections for the future climate (2011-2055) were made using Inter governmental panel on climate change (IPCC) scenario data sets of A1B, A2, and B1 of the HADCM3 global climate model based on different assumption of climate change projections which are continuous balance in green house gases emission, continuous increase in green house gases emission and continuous decrease in green house gases emission respectively for the future climate. The performance of the (RCM) data over the surface observed data was done using regression analysis and the result shows a good correlation (between 0.74 and 0.82) in all the stations under study. Drought years in all the stations for the future climate were projected and classified by their intensities into moderately, severely and extremely dry years using the standard precipitation index (SPI). The result shows many years of drought in the region for the future climate with Maiduguri station having most of the drought years (2011, 2015, 2021, 2027, 2028, 2029 2030, 2040 2042 2046, 2050 2055). Digitized SPI spatial assessment maps for the two climate regimes were produced to indicate areas of drought severity. The result shows decrease of rainfall from the south to the north of the region for each of the scenarios during the future with Nguru and Sokoto stations as the driest and Yelwa as the wettest station. From the result of the work, there is a high possibility of regular occurrences of drought with severe intensities if human activities in the region continue without proper consideration of the environment thereby allowing increase in the green house gases concentration in the atmosphere during the future climate (drought projections based on A2 scenario). The A1B projections also gave a high possibility of drought occurrences with lesser intensities than that of A2 scenario in the region. But this could be averted by introducing environment friendly policies with a view to protecting the atmosphere from excessive green house gases arising from human activities with a decreasing effect of drought occurrences and intensities in the region (projection based on B1 scenario).