Evaluation of Projected Distribution of New Urban Climates and Its Implications for Nigeria

Abstract

Responding to the threats of climate change by cities requires taking relevant actions that will communicate future conditions in reliable and effective manner for sustainable and transformational climate actions. As the population of urban areas in Nigeria continues to rise and changes in climate condition continue to have profound implications on the urban residents, a better understanding of the implication of these changes has informed this study. The study presents the current and future climatic conditions of major Nigerian cities in the past and the implications for future sustainable city related actions. The future climates of the cities were identified in the past under the different representative concentration pathways RCP4.5 (mitigation scenario), RCP8.5 (emissions continuing to rise throughout the 21st century). The climate similarity was calculated using CMIP5 data set which is a downscaled and biased-corrected projections of future climate for total monthly precipitation and average temperature (running mean of 2030s) and (running mean of 2050s). The results revealed that the climate of the cities in the current and future periods will be similar to conditions of another place on the globe during the historical period; Kano city will experience even more drastic changes because of the low level of similarity which is an indication of climate novelty; the new places found with similar temperature conditions are generally to the south of the corresponding cities thus indicating warming. The results also revealed that for temperature indices, the highest warming in minimum temperature is in Kano and Abuja while reduction in the number of cool nights and days occurred in all the cities. Precipitation indices show that the highest increase in the total precipitation is in Lagos at 124mm per decade while Kano shows a reduction of (-95mm per decade). A significantly increasing trend in the hottest day and warmest nights and the decreasing trends in the occurrence of cool days is an indication of warming for the cities. These are indications of increased exposure of the urban areas to climate disasters such as floods, heatwaves, and in Kano, water scarcity. By providing information on the future or current conditions of the cities in the historical period, land managers and city planners will understand and contextualize the future. Drawing from the interaction between cities and their analogues, the study highlighted sustainable city related actions such as the incorporations of urban designs and policies to enhance human thermal comfort as adaptation and solution strategies. While future research might apply qualitative studies and additional data to support the analogue results, our findings can guide the understanding and application of the analogue approach into environmental issues in Nigeria and other West African countries in accordance to sustainable city goals (SDG 11).