CHAPTER ONE
1.0 INTRODUCTION
Climate change seems to be the foremost global challenge facing humans at the moment. The seasonal northward and southward oscillatory movement of the Inter-Tropical Discontinuity (ITD) largely dictates the weather pattern of Nigeria. The moist southwesterly winds from the South Atlantic Ocean, which is the source of moisture needed for rainfall and thunderstorms to occur, prevail over the country during the rainy season (April – October). In reverse, northeasterly winds which raise and transport dust particles from the Sahara Desert prevail all over the country during the harmattan period (November – March). The overall changes in temperature, rainfall and other meteorological parameters determine the changes in climate in the country each year (NCRB, 2010)
The knowledge of climate variability over the period of instrumental records and beyond on different temporal and spatial scale is important to understand the nature of different climate systems and their impact on the environment and society (Oguntunde et al. 2012). Most of the observational and numerical simulation studies on climate are based on the instrumental records of about a century which are aimed at the understanding of the natural variability of climate system and to identify processes and forces that contribute to this variability. This is essential if we are to predict global and regional climate variations, determine the extent of human influence on the climate and make sound projections of human induced climate change. The climate of a location can be understood most easily in terms of annual or seasonal averages of temperature and precipitation. The global climate has changed rapidly with the global mean temperature increasing by 0.70C within the last century (IPCC 2007). However, the rates of change are significantly different among regions (IPCC 2007). This is primarily due to the varied types of land surfaces with different surface albedo, evapotranspiration and carbon cycle affecting the climate in different ways (Meissner et al. 2003; Snyder et al. 2004).
IPCC (2007) defines climate change as a change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and /or the variability of its properties, and that persists for an extended period typically decades or longer. Although the length of time it takes the changes to manifest matters, the level of deviation from the normal and its impacts on the ecology are most paramount. This prompted Ayoade (2003) to state that secular variations in climate occurring over a period of 100 to 150 years may not qualify as a climate change if conditions will quickly reverse later, but a change in climate usually takes place over a long period of time of at least 150 years with clear and permanent impacts on the ecosystem. Climate change is different from the generally known terms like climatic fluctuations or climatic variability. These terms denote inherent dynamic nature of climate on various temporal scales. Such temporal scale variations could be monthly, seasonal, annual, decadal, periodic, quasi-periodic or non-periodic. Climate change is caused by two basic factors, which include natural processes (biogeographical) and human activities (anthropogenic).
The natural processes are the astronomical and the extraterrestrial factors. The astronomical factors include the changes in the eccentricity of the earth’s orbit, changes in the obliquity of the plane of ecliptic and changes in orbital procession while the extra-terrestrial factors are solar radiation quantity and quality among others. On the other hand, the anthropogenic factor in climate change involves human activities that either emit large amount of greenhouse gases into the atmosphere that depletes the ozone layer or activities that reduce the amount of carbons absorbed from the atmosphere. The human factors that emit large amounts of greenhouse gases include industrialization, burning of fossil fuel, gas flaring, urbanization and agriculture. On the other hand, human activities that reduce the amount of carbon sinks are deforestation, alterations in land use, water pollution and agricultural practices. The human factors have been proven to be responsible for the ongoing unequivocal climate change or global warming (IPCC 2007).
Available evidences show that climate change will be global, likewise its impacts, but the biting effects will be felt more by the developing countries, especially those in Africa, due to their low level of coping capabilities (Nwafor 2007).
1.1 STATEMENT OF THE PROBLEM
Rising trends in the frequency and severity of heat waves have recently been observed in many areas, and there is a concern that these trends are likely to continue towards the future due to global climate change. Improved understanding of meteorological causes and present and future probabilities of such extremes is essential, among others, in deciding on measures that need to be adopted to mitigate future negative impacts of hot summer weather. It is to this purpose that the researcher seeks to investigate the anomaly of air temperature in Sokoto metropolis.
1.2 AIMS AND OBJECTIVES
The aim of this research work is to analyze air temperature anomaly of Sokoto, Sokoto State over the period of thirty years (1981-2010).
The specific objectives are;
i. To analyze the mean monthly air temperature in Sokoto metropolis
ii. To determine the air temperature anomalies in Sokoto metropolis
iii. To determine the inter-annual temperature variability
1.3 SIGNIFICANT OF THE STUDY
This research work will provide adequate information about air temperature, variation in the heat indices and Knowledge of the thermal climate of Sokoto, hence providing vital information for planning on health, urban development, tourism and migration, among other matters in Sokoto metropolis.
1.4 SCOPE AND LIMITATION OF THE STUDY
This research work is limited to the monthly mean maximum temperature data over Sokoto metropolis sourced from the Institute of Tropical Agriculture, Ibadan for the period of thirty years (1981 - 2010). The project work was carried out alongside normal lectures, and therefore the time was not enough to study other climate variables.
1.5 DEFINITION OF TERMS
Temperature: the degree of heat as an inherent quality of objects expressed as hotness or coldness relative to something else.
Anomaly: the deviation from the normal or from expectations.
Weather: the short term state of the atmosphere at a specific time and place, including temperature humidity cloud cover wind etc.
Climate: is the long term pattern of weather on a particular area; it is the average weather over a long time period, usually 30 years
