There is evidence that Nigeria is already experiencing environmental challenges attributed to climate change (CC) and its impacts. This has clearly highlighted the need for knowledge-based strategies to help plan adequate mitigation and adaptation measures for the country. One of the basic requirements to ensure such strategies is the development of a database of national CC research. This will aid in the assessment of past and present scientific publications from which directions for future study can be mapped. The present study used standard, systematic, and bibliographic literature reviews to analyse the trend, focus, spatial variability, and effectiveness of published research on CC impacts in Nigeria. Four thematic areas of CC impact research were defined: Agriculture, Environment, Human and Multi-disciplinary study. A total of 701 articles were found to be relevant and the review shows that CC impacts and adaptations in the literature vary across research categories and locations. The period between 2011 (68 studies) and 2015 (80 studies) showed a tremendous rise in CC impact research with a peak in 2014 (84 studies). Studies in the agriculture category had the highest publications in 23 States of Nigeria. The review revealed three research gaps: (1) lack of research that investigated the magnitude of present and potential future impacts in the aquatic environment (2) little attention on CC impacts and adaptation in the Northern regions of Nigeria (3) absence of study investigating the effects of multiple variables of CC at the same time. The findings suggest that it would be useful to advance CC research in Nigeria beyond perceptive approaches to more quantitative ones. This is particularly important for highly vulnerable animals, crops, locations, and for better planning of adaptation strategies.

This study examines the effect of climate change on the yield for four main grain crops in Nigeria (sorghum, maize, millet and rice) over the period 1970-2014. Cobb Douglas and Maximum Likelihood Estimation were explored to obtain reliable estimates. Results suggests that climate have diversified effects on grain yield and variability which shows that as the climate becomes warmer, higher yield variability can be observed on these selected crops. In addition more rainfall increases the yield variability on sorghum, maize, millet and rice. The increasing variation on rainfall also increased crop yield variability on rice. Based on the empirical findings it can be concluded that climate change, through an increase in actual average temperature and changing rainfall pattern has resulted to a decline in productivity of most food grain crops. This effect varies within crops and there is need to adapt different policies for various crops to mitigate the adverse effect of climate change in Nigeria.

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