Impact of climate variability on water footprint of sugarcane. A case study of the Dangote Sugar Company Numan, Adamawa State

Table of Content

DEDICATION

ACKNOWLEDGEMENTS

ABSTRACT

LIST OF TABLES

LIST OF FIGURES

LIST OF APPENDICES

ABBREVIATIONS

CHAPTER ONE

INTRODUCTION
1.1 BACKGROUND OF STUDY
1.2 STATEMENT OF PROBLEM
1.3 AIM AND OBJECTIVES
1.4 HYPOTHESIS
1.5 SIGNIFICANCE OF STUDY
1.6 STUDY AREA
1.6.1 LOCATION AND EXTENT
1.6.2 CLIMATE
1.6.3 GEOLOGY AND TOPOGRAPHY
1.6.6 ECONOMIC ACTIVITIES AROUND THE SUGARCANE ESTATES

LITERATURE REVIEW
2.1 I NTRODUCTION
2.2 CONCEPT OF CLIMATE CHANGE AND VARIABILITY
2.2.1 MECHANISMS OF CLIMATE CHANGE
2.2.2 MECHANISMS OF SEASONAL TO INTER - ANNUAL VARIABILITY
2.2.3 CLIMATE CHANGEAND WATER RESOURCES
2.2.4 CLIMATE VARIABILITY AND SUGARCANE CULTIVATION
2.3.1 WATER FOOTPRINT (WF) CALCULATION
2.3.2 GREEN , BLUE AND GREY WATER
2.3.3 CROP WATER FOOTPRINT
2.4 T HE SUGARCANE CROP
2.4.1 MORPHOLOGY OF SUGARCANE
2.4.2 CLIMATE OF SUGARCANE
2.4.3 PLANTING OF SUGARCANE
2.4.4 WATER MANAGEMENT
2.4.5 PRODUCTS DERIVED FROM MAIN PRODUCT AND BY PRODUCT OF SUGARCANE

CHAPTER THREE
METHODOLOGY
3.1 R ESEARCH DESIGN
3.2.1 CROPWAT MODEL

CHAPTER FOUR
RESULTS AND DISCUSSION
4.1 INTRODUCTION
4.2 S UGARCANE YIELD AND HARVESTED HECTARES
* CORRELATION IS SIGNIFICANT AT P < 0.05
4.5.1 CORRELATION ANALYSIS
4.5.2 PATH ANALYSIS
SUMMARY, CONCLUSION AND RECOMMENDATIONS
5.1 S UMMARY
5.2 C ONCLUSION
5.3 R ECOMMENDATIONS

REFERENCE

APPENDICES

DEDICATION

This research thesis is dedicated to my heavenly Father and our Lord Jesus Christ for Zoe that is at work in me. Also, to my parents Rev & Mrs Livinus Obi, for their immeasurable love and support. You made it happen. I love you.

ACKNOWLEDGEMENTS

Thanks be unto my God who has made me met to be accounted for as a seed of Abraham and a minister of reconciliation in this regeneration. Your kingdom is everlasting.

Many thanks to a lot of people who have in various ways contributed to the success of this research. Special thanks to my amiable Lecturer and Supervisor, Dr. A.A Zemba. Thank you sir for your exceptional understanding. I am also grateful to all my lecturers of Geography Department, Modibbo Adama University of Technology, Yola; Professor A.A. Adebayo, Professor M. Galtima, Professor A.L Tukur, Professor A. Bashir, Dr. H. H Ray, Dr. A.M Mubi, Dr. A.S Umar and Dr B. A Bashir, for their contributions in schooling me, thank you so much. To my valued Professor R. Odekunle and Dr V. Eneji for their constant follow up on my study work, God bless you sirs. To some other wonderful lecturers that have been of encouragement to me, Dr M. Ibrahim of Survey department, and Malam Mahmud, thank you so much. I will not fail to recognise Mrs Comfort and Mr Danjuma of the Geography department, they were like guardians to me right from my undergraduate days. My God bless you. To Mr Okoye of the UBRBDA Yola, I say a big thank you Sir.

I will like to appreciate the special support of my uncle Mr & Mrs Stephen Obi, my heart is full of gratitude for your immerse support. To my siblings Mrs Goodnews Martins, Shalom, Sharon, Christabel, David and Joy Jibril, your support and prayers have done a lot for me, thank you all. To my beloved brethren and friends Edward Ehizibue, Isaiah Nuhu, Peter Costan, Ogechukwu, Maranatha Ngene, Nacha Suleiman and Elizabeth Osamezu, you’re valuable to God and to me also. I love you all.

To my friends and colleagues, I will not neglect your support and friendship, Solomon Adediran, Jamilu Usman and Kabiru Shehu, you were like family to me, thank you. To all my course mates, quite a number of you, I appreciate your support, meeting you all has made life more interesting. God bless you.

ABSTRACT

There is an anticipation of a restructuring of the patterns of demand and supply of water for agriculture owing to possible effects of change in climate. Thus, the assessment of the influences of climatic variation on water consumption for agriculture is of import. Water footprint as an indicator provides a different methodology to the assessment of agricultural water consumption under variability of climate. This study offers an analysis of the impact of climate variability on the water footprint of sugarcane in Dangote Sugar Company, Numan during 1981-2013. Climate data was collected for a period of 33 years. Using the CROPWAT model, water footprint for sugarcane was calculated. The outcome was later correlated using the SPSS and SPSS AMOS 21 packages to find the relationship between water footprint of sugarcane and the climatic variation. Also the impact climatic variables had on water footprint of sugarcane was deduced. The results indicated that a) crop evapotranspiration and irrigation water requirements of sugarcane in the study area presented an uptrend and this is due to the variation in climatic factors; b) green water footprint (102 m3/ton) was lower than the blue water footprint (172 m3/ton) and; c) the climatic factors accountable for 17% of the variation in water footprint of sugarcane under the study period. From the results, it was observed that water footprint of sugarcane is influenced most by the rainfall element. However, there are other agricultural management factors that may also have an effect on it, even higher than that of climate. Attention however must be given for adaptation of effective strategies to reduce the agricultural production risk associated with climate change in the long run.

LIST OF TABLES

1: Advantages, Limitations and Application Time Step of Different ET Estimation Models

2: Type of Data Required for Inputting into CROPWAT

3: Correlation Analysis among ETc, WF (Green and Blue) and Climate Factors

4: Global and DSC Average Water footprint of Sugarcane

5: Regression Weights for Relationship between WFblue, WFgreen and Climatic Factors

6: Standardized Regression Weights

7: Summary of Results on the Impact of Climatic Variables on Water Footprint Using Correlation Analysis and Path Analysis

LIST OF FIGURES

1: Numan LGA where Study Area is Located

2: Study Area and Kiri Dam

3: Trends of Mean Annual Rainfall in Savannah Sugar Project area

4: Trends of Minimum and Maximum Temperature in Savannah Sugar project area

5: Water Footprint of National Consumption per Capita

6: The Water Footprint of Sugar Cane for the Main Producing Countries

7: Methodological Approach

8: Distribution of Sugarcane Yield and Hectares Harvested 1981-2013

9: Interannual Variability of Crop Evapotranspiration (ETc), Effective Precipitation (Eff) and Irrigation Water Requirements (IWR) of Sugarcane

10: Percentage Distribution of Green and Blue (WF) of Sugarcane, 1981-2013 of Study Area

11: Interannual Variability of Green Water Footprint and Blue Water Footprint of Sugarcane over the Study Period of Farming Activities Observed

12: Path Diagram Showing the Effect of Climatic Variables on Blue Water Footprint (WFblue) of Sugarcane

13: Path Diagram Showing the Effect of Climatic Variables on Green Water Footprint (WFgreen) of Sugarcane

14: Path Diagram Showing the Effect of Climatic Variables on Water Footprint (WF) of Sugarcane

LIST OF APPENDICES

I: Climatic Data for Gyawana for the Year 1981-2013

II: Sugarcane Planting Date and Generated Data from CROPWAT

III: Data for Calculating Water Footprint of Sugarcane

IV: SPSS Correlation Analysis Result

V: SPSS AMOS Path Analysis for Blue Water Footprint and Climate

VI: SPSS AMOS Path Analysis for Green Water Footprint and Climate

VII: SPSS AMOS Path Analysis for Water Footprint and Climate

ABBREVIATIONS

Abbildung in dieser Leseprobe nicht enthalten

CHAPTER ONE

INTRODUCTION

1.1 Background of Study

The world has over the past decades experienced a continuous deterioration in climatic condition. Climate change, agriculture and water security is now a global subject of concern. This statements are true arising from the volume of literatures currently available about these concerns. However, a good number of the studies seem to give more attention to developed countries. Due to economic and technological wherewithal, they are better prepared to adapt to the changes. In developing countries, not much has been done even though the developing nations seem to feel the impacts more.

Climate change and global warming have further contributed in intensifying water challenges especially for the arid and semi-arid zones (Kim, 2012). This has led toa diminishing of fresh water supplies annually. Climate change most likely increases water scarcity by reason of modifications in the patterns and intensity of precipitation. Much of the world’s poorest populations live in the subtropics and mid-latitudes. These areas are projected to turn out significantly drier, resulting in intensified water scarcity. A new Massachusetts Institute of Technology study also shows that reduced precipitation in some arid regions could trigger exponentially larger drops in groundwater tables (Morrison et al., 2009).

Fresh water is a necessary requirement for all economic activities especially for agricultural purposes. Agriculture on the other hand has been identified as a major water using sector accounting for over 70% of global water withdrawals (FAO, 2011; Dourte & Fraisse, 2012; Zoumides et al. 2014). In confirmation, Adams and Peck (2008) mentioned that effects of climate change on water resources availability and quality will have an impact on several sectors of the economy including agriculture, energy production and ecosystems. The water need per unit of product depends on both climate and water-use efficiency.

In 2002, Allan Hoekstra introduced the Water Footprint (WF) indicator as a means to represent the water use for commodities. The WF of a commodity is thus defined as the aggregate volume of freshwater used throughout the production process. For crops, their water use comprises largely of water (green and blue water) consumed during the growing period and grey water, that is the volume of water required to dilute a certain amount of pollution for it to meet ambient water quality standards (Hoekstra and Chapagain, 2008). The water footprint is a helpful tool in the quantification of water use through a process. It provides valuable insights into the component and location in a process having the largest water consumption (Ene et al. 2012).

Sugarcane (Saccharumofficinarum.) is a very important crop in the world in general. This is owing to its immense usefulness in the daily consumption of any society as well as for industrial purposes of small, medium and large scale production. Girei and Giroh (2013) acknowledged that Sugarcane contributes around 60% of the total global sugar demand whereas the remaining 40% comes from sugar beet. Aside from the production of sugar, the sugarcane crop is a suitable raw material in the production of biofuels such as ethanol that is useful in the reduction of dependence on fossil fuels and possibly mitigate climate change (Dominguez-Faus, 2011).

1.2 Statement of Problem

Sugarcane is one among the three most important food crops with a huge contribution to global agricultural food production. An agricultural crop like sugarcane is very water intensive hence, the intensification of its cultivation will aggravate the over exploitation of freshwater consumption. Currently, over 70% of freshwater withdrawals are applied in agro related uses. There is a growing competition for water resources plus the climate change on the global hydrological cycle. It is expected that the modifications in climate will restructure the patterns of demand and supply of water for both rain-fed and irrigated agriculture especially for Nigeria as one of the countries with a documented high inefficiency in water use especially for agricultural purposes (Kim, 2012). For instance, FAO (2011) reported that increasing temperature conditions will engender increased evapotranspiration in crop, variation in yield and water productivity. Therefore, it is important that for proper adaptation in the agricultural system to changing climatic conditions, knowledge on the effect climate will have on agricultural production and water use efficiency will be required. This forms the bases for the utilization of the water footprint concept in the study.

So far, a lot of research work on water footprint of sugarcane since the first efforts made by Hoekstra and Hung (2002) to provide the first global estimation of freshwater needed to produce crops. Chapagain and Hoekstra (2004) later created the first global dataset for major agricultural products after which years later Mekonnen and Hoekstra (2011) improved on it. Several studies assessed the water footprint of food crops and energy crops. Chapagain and Orr (2007) improved on the WF methodology, linking global consumption to local water resources, focusing on Spanish Tomatoes. Lindholm (2011) explored the WF of oat and other oat products for the south western Finland. For Sudan, Ahmed and Ribbe (2011) attempted an assessment of water consumption of crops using the WF and virtual water concept. Kim (2012) investigated the WF for seed cotton in Turkmenistan, focusing on blue water. Specifically, for energy crop, Kongboon and Sampattagul (2012) and Tiewtoy et al. (2012) made an assessment of water footprint for sugarcane and cassava for northern and eastern Thailand. Gerbens-Leens and Hoekstra (2011) showed that the crop WF of sugar from sugarcane is much more than that of maize and sugar beet.

These studies have focused on water footprint and crop production from a consumptive perspective. A gap left by these studies is the climate change perspective from which water footprint is being affected. Not much has been done in investigating the place of climate change as a global phenomenon on the water footprint of crops in Nigeria as a whole. This study assesses the water use of sugarcane, including the role climate change through its several factors has on water footprint of sugarcane crop for a Guinea savannah environment with a tropical climate (marked by dry and rainy seasons); the Dangote Sugar Company savannah area.

1.3 Aim and Objectives

This study is aimed at analysing the impact of climate variation on water footprint of Sugarcane using the sugarcane estate of the Dangote Sugar Company as a case study. Within this framework, the study’s specific objectives include to:

i. Determine the green and blue water footprint of sugarcane production.
ii. Assess the contribution of the individual climatic parameters to each of green and blue water footprint of sugarcane.
iii. Examine the relationship between climatic elements and overall water footprint pattern of Sugarcane.

1.4 Hypothesis

Ho: There is no relationship between climate parameters and water footprint of Sugarcane.

H1: There is a relationship between climate parameters and water footprint of Sugarcane.

1.5 Significance of Study

Water footprint as a tool is relevant in helping societies and organizations better analyse their water resource consumption behaviour in order to identify alternative levels for reducing water stress and for companies to monitor their reliance on scarce water resources along their supply chain. In the light of climate variability, the study will be able to provide not only evidence for water resources and water footprint, but also new trend of thought for the development of water footprint and climatology in Adamawa state.

Judging from the scarcity of literature on climate and water footprint specific to Nigeria, this work served as an empirical awareness creator on the application of water footprint analysis as a tool in general resource sustainability studies for Nigeria, both for academic and non-academic purposes. It opens the door for further studies for the purpose of advancement of indicator formulation towards promotion of resource sustainability and climate. The Dangote Sugar Company Ltd (DSC) in line with its agenda for the integration of its sugar production to Green Cane Farming, in keeping with the Nations’ New Sugar Master Plan, an assessment of this sort stands to be of significant benefit to the company and environment as a whole. Sugarcane produces more biomass dry matter per hectare than any other crop species. Therefore, it can have a strong positive impact on the environment and so has a great future in providing food and/or energy in a sustainable way for a greener climatic environment. The findings not merely would be of use to stakeholders and policymakers for better water management but also could be used as basis data of sub-national water footprint for crop production.

Some of the main concerns for many stakeholders in climate and environmental resource issues has to do with climate change and natural resources. Because climate affects the availability and sustainability of these natural resources like water, directly or indirectly, it is only smarter to be proactive. Proper know-how on their nature and extent and nexus will create a bases for informed decision making if these resources will serve humanity for the coming generations. There is a general wide spread quest for cognizance vis-a-vis sustainability standards. One area of sustainability that has drawn a lot of attention in recent years is that of climate change and resource utilization. It is expected that in the long run, conforming to such standards will save money, as resources are used more responsibly and a cut back on waste and pollution is achieved.

1.6 Study Area

1.6.1 Location and extent

The study area as in Figures 1 and 2, covers an area located between latitudes 9o22' N and 9o38'N and longitudes 11o45'E and 12o00'E, covering the farm and the factory of the Savannah Sugar Company. The Savannah Sugar company being the main focus of the study is located north of the River Benue and 20km North of Numan town in Adamawa state, North East Nigeria (Dangote Sugar Company Ltd., 2014) as seen in Figure 1. It lies at an elevation of 150m above sea level (Mirchaulum and Eguda 1995). The company has a land mass of about 32,000 unfenced hectares spread, north of the Yola-Gombe highway within Bafio,

Gyawana, Zekun, Opalo, Zangun and Imburu communities of the Bachama tribe. To the south, Savannah is spread within Kwapukai, Sabon Pegi, Kem and Kola communities mostly of the Lunguda and Kanakuru tribes with a few others like the Hausas, Bares and Wajas (SSCL, 2014).

Abbildung in dieser Leseprobe nicht enthalten

Source: Adapted from Mirchaulum (1999)

Figure 1: Location of Study Area in Numan LGA

Abbildung in dieser Leseprobe nicht enthalten

Source: Adapted from Google Earth of 29/02/2016

Figure 2: Study Area and Kiri Dam

The out grower farms of the Savannah Sugar Company are situated in six out grower zones, respectively managed by estate mangers. They include Zekun, Gyawana, Lafia, Danto and Opallo estates. Irrigation is done by the use of irrigation water from Kiri Dam (Figure 2), connected from a 30km distance canal to the sugar cane estates which commences two or three weeks after the rain stops (Gireh & Giroh, 2013).

1.6.2 Climate

The climate of the area is that of the semi-arid type, Guinea Savannah to be precise, characterized by wide seasonal and diurnal temperature ranges. There are two main marked tropical seasons in the study area. The wet season lasting from April-October has a mean rainfall of about 905mm with its peak in August and September (Yahaya, 2013; Binbol, 2006).

Between November - January the Harmattan pushes the Inter Tropical Discontinuity (ITD) to its most southerly latitude position of 2-5°N. All through this period, most of Adamawa State is influenced comparatively by stable dry continental air mass from the NE and hence rainfall is actually low (Adebayo 1999). The dry season is from November -March. Averagely, the monthly temperature is 26.9°C, with minimum temperature of 18oC and a maximum of 40°C (Binbol, 2006).

The Savannah Sugar project area which includes the study area has displayed a variability in climate over an observable time from 1975-2010 (Adebayo and Yahaya, 2015). Breaking down climatic factors of rainfall, minimum and maximum temperatures, on a temporal scale to period before and after the sugar project, they authors identified a general warming and drying of the climatic environment around the study area. Rainfall was found to be declining by about 5mm/year in Figure 3. This is indicative of a drying period. Olaniran (2002) reported a 50-75mm decline in the rainfall data of the Yola-Enugu axis from 1971­2000. The findings of Adebayo and Yahaya (2015) agrees with Olaniran (2002).

Temperature was found to rise by about 0.841oC per decade as seen Figure 4 and this development was attributed to the landuse change and other activities relating to the sugar manufacturing company (Adebayo & Yahaya, 2015). This finding supports Adebayo (2010) of a 0.867oC rise in the temperature of Yola, Nigeria. On a global scale, Sachez-Lorenz (2009) in Adebayo & Yahaya, (2015) reported a 0.13± 0.03oC rise in mean surface temperature in over 50 years past. The major sign of greater warming nocturnal in majority of world regions. However, this warming is unevenly distributed globally.

Yahaya (2013) research included an analysis of climatic trends indicated that there has been a significant variation in climate in the entire savannah sugar area which includes the study area. The independent variable of time accounts for the variation in 23% of relative humidity (readings taken at the 9am daily), 62% of evaporation, 90% of sunshine and 32% of wind run.

Abbildung in dieser Leseprobe nicht enthalten

Source: Adebayo & Yahaya, (2015)

Figure 3: Trends of Mean Annual Rainfall in Savannah Sugar Project area 1975-2010

Abbildung in dieser Leseprobe nicht enthalten

Source: Adebayo & Yahaya, (2015)

Figure 4: Trends of Minimum and Maximum Temperature in Savannah Sugar project area 1975-2010

Between the months of August/September and February/March, the relative humidity can read as high as 77.9% and as low as 16.3% respectively. Sunshine hours of 6-8hr/day are enjoyed in the area, with high wind speed of 152 km/hr on the average (National Sugar Development Council, NSDC 2001). Mean annual evaporation is approximately 10mm.

1.6.3 Geology and topography

According to Bawden (1972), the area is underlain by the upper cretaceous rocks of marine sediments. The major components from shale are limestone, sandstones and siltstones. The study area falls among the plains of the extensive Benue valley, gently undulating to nearly flat beneath the Lamurde Lunguda plateau (Yahaya, 2013). The author also recognized a primary topographical feature of sandstone hills/knolls as well as anthills. The average elevation of this region ranges from 152-259m above sea level. The topography of the area consists of alluvial plains along the Benue River and its tributaries (Binbol, 2006).

1.6.4 Soils

The study area has good and favourable soil made up of alluvial and vertisol soils (Tukur and Adebayo, 1997). Gireh and Giroh (2013) reported that the vertisols of the Savannah Sugar Company Numan are derived from quaternary alluvium underlain by the Bima sandstones found on nearby level plain. However, Mirchalum and Eguda (1995) reported that the Savannah Sugar Company Vertisols owe their origin from the olivine basalts of the Lunguda plateau. The vertisol soils is that which is present in depressions and low- lying areas, which are usually heavily dark soils derived majorly from argillaceous sediments, rich in iron concentration and deep wide cracks when dry. This type of soil is structurally sticky, with colours between dark gray. Virmani (1987) made reference to the high productivity of vertisols if managed properly and also their relative susceptibility to erosion. He recommended that soil and climatic parameters be studied alongside for better understanding of crop environment in the regions with vertisol. The author noted that length of growing season is closely related to soil-water balance (Vahyala et al., 2013).

Tekwa et al. (2013), showed some characteristics of the soils as having a heavy presence of clay content of about 70% the vertisol soils; bulk density ranges from 1.25-1.40 mg/m-3in fallow soils and 1.47-1.52 mg/m-3in cultivated soils; porosity of about 43% in fallow soils and about 40% in cultivated soils; soil moisture content extending between 65% - 80%. Generally, they are regarded as difficult soils to be cultivated owing to poor drainage, low nutrient and organic matter contents.

1.6.5 Flora and fauna

Under the agro-ecological zone, the study area is found among the Sudan Savannah vegetation. The company owns a 32,000 hectares of land area. Some portion of the land around the sugar company have been cleared for mono-culturally agricultural activities of Sugar cane cultivation. There are however large portions of uncultivated fallow land with natural vegetation such as Acacia spp., Calotropisprocera, etc. Following the study of NSDC (2001), the community of animals around the study area associated with the cane fields basically include Quale birds, snakes, crabs and snails, termites, ants, frogs/toad and bees.

1.6.6 Economic activities around the sugarcane estates

The defunct Savannah Sugar Company Limited now Dangote Sugar Company commenced commercial production in 1980 however Binbol et al. (2006) noted that the main factor influencing the variation in crop yield is climate. The major settlements around the Sugar Company: Gyawana, Opallo, Kem and Rigange have traditionally practiced other forms of land resource exploitation like peasant rainfed farming, but with the coming of the company, basically the canal from the Kiri dam, irrigated farming have commenced aside that of the sugarcane estates. Under the out-growers scheme of the company, up to 5000 people are engaged in the cultivation of sugarcane for the sugar mill (Yahaya, 2013). The out grower farms are located in some zones namely Zekun, Gyawana, Opallo, Danto and Lafia. The sugarcane project production covers approximately 27,000 hectares. After the first phase of rehabilitation in the Dangote Sugar Company, about 6700 hectares of sugarcane fields are newly cultivated (GAIN Report, 2013). Also reported is that sugar cane yield decreased from 66 tons per hectare in 2010/2011 to 60 tons in 2011/2012. The average yield of refined sugar from a ton of cane is estimated at approximately 0.961 or 9 percent (GAIN Report, 2013).

Sugarcane cultivated in the study area takes averagely 12 months to be due for harvest. About 1100-1500mm of water hence the application of irrigation water even during the rainy season as the rain water is inadequate for its growth to rely on.

1.7 Delimitation and Limitation

The data presented in this study is based on climatic period 1981-2013 and fresh water requirement in crop production with optimal assumptions. For assessment of the water footprint of sugarcane, the study integrated information from several sources which adds a degree of uncertainty. For example, the CROPWAT software required input on planting date. No data on planting dates were provided by the company under study. Thus, the planting date used for the model was assumed, counting 11 months backwards form the harvesting dates provided (bearing in mind that the sugarcane crop matures under 12 months averagely). This of cause is not the same as the actual planting date as used by the company. Unavailability of data for some other inputs was also a challenge. For instance, soil and crop parameters required for the CROPWAT model was unavailable. This challenge was overcome by applying the generalized data gotten from the CROPWAT package. This however may differ from the actual data for the crop.

Due to challenges encountered by the company in previous years, there were years without any record of farming activities. These years include 1983/84, 1996/97 and 2003­2006. These years were not accounted for in the determination of water footprint of sugarcane.

CHAPTER TWO

LITERATURE REVIEW

2.1 Introduction

The discussion in this chapter will revolve around relevant literatures akin to this research topic. Works involving climate change and variability, green and blue water, water resource use and sugarcane crop production were reviewed. In relation to the research objectives, this chapter is presented in three captions: (a) Climate Change/Variability (b) Water Footprint (c) Sugarcane Crop.

2.2 Concept of Climate Change and Variability

There are earth system interactions of atmosphere, biosphere, hydrosphere and geosphere that are influenced by human activities. This implies that the changes in one part of the system will have a positive or negative effect on one or more other systems (Vladlmir, et al. 2011). Climate change may occur over a duration of time, ranging from decades (30 years and above) to millennia. Ayoade (2003) argues that a 30-year period is not sufficient time to declare a change in climate. Rather, when the changes that occur are more than 150 years then an alarm on climate change will be appropriate. This changes according to Abiodun et al. (2011) may affect one or more seasons or the whole year, and involves changes in one or more aspects of the weather such as rainfall, temperature or winds. Climatic anomalies occur when observations of substantial departures from the normal on monthly, seasonal or annual basis are made. These departures are more or less fluctuations (Adakayi, 2012).

The Intergovernmental Panel on Climate Change (IPCC) has been at the fore front in driving the global responses to climate change, providing predictions and projections. IPCC Working Group 1 (2007) acknowledged that there was a wide knowledge of the detected rise in global temperatures for some decades linked with human activities. Nevertheless, there is uneven distribution in global temperature increase. As at 2005, world average surface temperature had increased by around 0.74oC within 1906-2005. In some regions, greater change is experienced, specifically the hinterlands of continental regions such as those of the Sahel in West Africa. Besides, the increasing rate of change in the global average temperature is an indication that temperature is rising more rapidly. Significantly, this rise in the rate of change is expected to continue theoretically bringing about speedier changes in climate for the future. This points to the conclusion of a warmer earth, rising from the fact that global temperatures are set to be greater than they are at the moment and again because of the pressures to be applied on the available resources to make sure they carter for a bigger population.

IPCC (2013) reported that there have been observed changes in the atmosphere, cryosphere and ocean. Also, it was reported that 1983-2012 is the 30 years’ period with the warmest surface temperature trend in the northern hemisphere. Also, that the globally averaged combination of land and ocean surface temperature showed warming of 0.85 [0.65­1.06] °C, over the period 1880-2012. The total increase between the average of the 1850­1900 period and the 2003-2012 period is 0.78 [0.72 to 0.85] °C, based on the single longest dataset available. For the ocean, the IPCC (2013) WG1 reported that for the increase in energy stored in the climate system, ocean warming is dominant, accounting for over 90% of energy accumulation between the periods 1971 and 2010. In the cryosphere, the report was that the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover is undergoing persistent drop in extent over the last two decades. The report also captured that the rate of global mean sea level rise over the period 1901-2010, rose by 0.19 [0.17 to 0.21] m. Furthermore, the atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have enlarged to extraordinary levels in at least the last 800,000 years. Concentrations of carbon dioxide have risen by 40% since pre-industrial times, mainly from emissions of fossil fuel and secondarily from net land use change emissions. The ocean has absorbed around 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification.

The report also captured that the frequency and intensity of drought has prospectively increased in the Mediterranean and West Africa, and likely decreased in central North America and north-west Australia. This is in line with Gleyzes, (2007) that the length and concentration of drought has increased over wider areas since the 1970s, particularly in the tropics and subtropics.

Projections for climate change by the IPCC (2013) conveyed that:

- Global surface temperature changes for the end of the 21st century will probably go above 1.5°C
- The difference in precipitation between wet and dry regions and between wet and dry seasons will increase
- Though there may be regional exceptions global ocean will continue to warm during the 21st century
- Heat will penetrate from the surface to the deep ocean and disturb ocean circulation
- Arctic sea ice cover will continue to shrink and thin
- Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises
- Global glacier volume will additionally decrease
- Climate change will affect carbon cycle processes in a way that will impair the increase of CO2 in the atmosphere and further uptake of carbon by the ocean will increase ocean acidification.

Ever since the beginning of the Holocene period, the tropics have experienced large and occasional sudden fluxes in the water balance. Water levels were generally high in the equatorial region and Northern hemisphere at the beginning of the Holocene, a trend that was akin to many Southern Hemisphere records. Aside the event of desiccation in many African lakes between 8000 and 7,500yr BP, the water levels increased until C. 5000yr BP. Intermediate to high lake levels existed in the Southern Hemisphere sites at C. 6000yrs BP. The drying phase that the tropical lakes experienced was between 5000 and 3000yrs BP. For instance the tropical lakes like the Lake Chad experienced desiccation between 5000 and 3000yrs BP, and has continued to dry till now (Adakayi, 2012).

Adakayi (2012) also captured that El Nino Southern Oscillation (ENSO) and land cover change are two potentially imperative drivers of African climate variability. Therefore, in respect to inter-annual rainfall variability in Africa, the ENSO plays one of the most substantial roles. El Nino refers to the warming of surface waters while Southern Oscillation refers to changes in the Walker Circulation. The period of warmer than normal sea surface temperatures is often followed by a cold phase (La Nina) in which waters in the eastern Pacific are abnormally cold. El Nino (warm episodes) and La Nina (cold episodes) are opposite extremes of the ENSO cycle. El Nino episodes are characterized by abnormally warm sea surface temperatures across the eastern equatorial Pacific. During a strong El Nino episode such as in 1997, the 28°C isotherm extends well east of the dateline and ocean temperatures are more than 2 - 3°C warmer than normal between the dateline and the west coast of South America. During the El Nino episodes, the normal difference between high pressure over the eastern tropical Pacific and low pressure over the west, which drives the easterly trade winds, diminishes. This is seen in the Southern Oscillation Index, which quantifies the difference in sea level pressure between Tahiti and Darwin, Australia. Prolonged periods of a negative phase, with below normal air pressure at Tahiti and above normal air pressure at Darwin, coincide with abnormally warm water in the eastern tropical

Pacific. This reflects a reduced strength of the Walker Circulation whose pattern changes every few years. There is a large-scale warming of sea surface temperature in the tropical Pacific east of the dateline recognized as El Nino (Bonan, 2002).

2.2.1 Mechanisms of climate change

The causes may be natural or attributed to human (anthropogenic) activities. Some of the natural processes influencing the natural changes in climate (Bonan, 2008) include:

a. Plate tectonics , which alters the distribution of continents and oceans and produces mountain ranges;
b. Geometry of Earth’s orbit around the Sun , responsible for changing the aggregate of solar radiation received by the Earth;
c. Chemical composition of the atmosphere , implying that increasing concentrations of water vapour, CO2, methane, nitrous oxide, and other radiatively important gases in the atmosphere warm climate through the greenhouse effect;
d. Changes in the cycling of water over land , altering the runoff of freshwater to oceans and the thermohaline circulation;
e. Solar variability , in which the amount of radiation emitted by the Sun varies in relation to sunspot activity; and
f. Aerosols in the atmosphere , which alters Earth’s radiative balance.

In present-day use, the term "climate change" frequently denotes changes caused by anthropogenic factors (BNRCC, 2011). The role of human influence has been noted as a major contributor in the warming of the atmosphere and ocean, changes in the global water cycle, reductions in snow and ice, global mean sea level rise, and in changes in some climate extremes (IPCC, 2013). Human influences on climate change include for instance accumulation of emissions of greenhouse gases like CO2, land use change and/or emissions of aerosols. Bonan (2008) mentioned that before 1850, the emission of CO2 in fossil fuel combustion was relatively negligible. As societies industrialized and population grew, the annual emission rate has increased so much so that currently, annual human activities emission is about 6.5 x 1015 g C to the atmosphere annually. Burning of fossil fuels accounts for the larger portion of the increase in atmospheric CO2. Also, land use practices such as, deforestation and reforestation contribute to a net release of an additional amount equal to 15% of the fossil fuel emission. Nevertheless, only about one-half of the total anthropogenic emission of CO2 is remaining in the atmosphere (Bonan, 2008). Gleyzes (2007) holds that the yearly emissions of carbon dioxide as at 2007 were 26% higher than those of 1990; energy consumption in the household sector increased by about 40%; between 1996 and 2004, distances travelled via private cars increased by almost 17%; and the number of passenger kilometres by means of plane rose from 125 -260 billion worldwide amid 1990 and 2000.Continued emissions of greenhouse gases will cause more warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions (IPCC, 2013).

Bonan (2008) suggests that there has been an increase in methane and nitrous oxide concentration in the atmosphere. Methane is emitted during agricultural activities and the decomposition of wastes in landfills, production and transportation of coal, natural gas and oil. Nitrous oxide on the other hand is emitted during agricultural and industrial activities and during combustion of fossil fuels. When forest areas are converted to cultivated lands and agricultural inputs like fertilizer or manure are applied on farms, nitrous oxide emission is increased.

2.2.2 Mechanisms of seasonal to inter-annual variability

There are several factors that determine the air masses that control a geographic region at a given period. The atmosphere could be a chaotic system wherein a small-scale atmospheric events may produce large-scale consequences. Bonan (2008) gave an example of this chaotic behaviour as described in Lorenz (1993) is the infamous butterfly effect by which the flapping of the wings of a butterfly flapping in Asia could produce events affecting weather over the United States. The chaos theory however places a limitation on the predictableness of weather for more than several days. Therefore, forecasters can never exactly identify all the conditions affecting weather. Variation in tropical circulation and precipitation do impact seasonal temperature and precipitation all over the world (Bonan, 2008).

The trade winds blowing from east to west around the equator drive warm surface water temperatures westward across the tropical pacific resulting in an extensive pool of warm surface water with temperatures in excess of 28°C around Australia and Indonesia. Distinct from the former is the condition of cooler degrees in the waters of the eastern Pacific, off the Peruvian and Ecuadorian coast of South America, as the warm surface water is replaced by deep cold water. This trend of warmest temperatures in the west and coldest temperatures in the east is manifest all through the year, although it is highest in late summer and early autumn when sea surface temperatures in the eastern tropical Pacific reach a minimum (Bonan, 2008).

Accompanying the pattern of warm surface water in the western tropical Pacific and cold surface water in the eastern tropical Pacific is the large-scale atmospheric circulation across the Pacific: the Walker Circulation. This circulation is described by low-level easterly winds and upper-level westerly winds across the Pacific. Over the western tropical Pacific, where the air is warmed by the warm seas, there is low surface air pressure and ascending motion. In this region, the warm, moist air rises to form deep clouds that produce heavy rains over northern Australia, Indonesia, and the Philippines. In disparity, the eastern tropical Pacific, where the air is colder, has higher surface pressure and descending air motion. Rainfall is light in this region of sinking rather than rising air (Bonan, 2008).

2.2.3 Climate change and water resources

Adams and Peck (2008) are of the opinion that effects of global climate change are having significant consequences for water resources include increased rates of evaporation, and mentioning that water supplies in many regions are expected to reduce due to increased evaporation rates. Other effects include a higher proportion of precipitation received as rain rather than snow, earlier and shorter runoff seasons, increased water temperatures, and decreased water quality both for inland and coastal areas. Gleyzes (2007) also added that drier climatic conditions in arid and semi-arid parts of the world will make conditions of water scarcity in the world more tightly in the future. The greatest deficits are expected to happen during the summer, which will lead to decreased soil moisture levels and more frequent and severe agricultural drought. All of these is arising from climate change which will have serious management implications for water resource users. Agricultural producers and urban areas are particularly vulnerable, (Adams and Peck, 2008). In Nigeria, the geographical location of the northern region is generally prone to drought, wind and water erosion. Adelalu (2012), has shown that both rainfall and runoff along the Benue River have experienced significant decline over a 49 years duration in Yola, so that for every 0.01mm rise in rainfall there was Imillion m3 increase in discharge and vice versa.

2.2.4 Climate variability and sugarcane cultivation

Local climate structure is strongly being affected by global climate change as well as climate variability (Eriksen, 2005). Temperature and evaporation increases coupled with conditions of relative drought persistence in the Sudan-Sahelian region of Nigeria (Binbol et al., 2006), is expected to lower crop yields and consequently affecting the sugarcane industry in Nigeria significantly.

In studying the impact of climate on the growth and yield of Sugar cane, Binbol et al. (2006) concluded that evaporation at boom stage and minimum temperature at germination stage are the critical climatic factors with a major effect on the variations in crop yield. Evaporation alone at boom stage accounts for 59.8% of the yield variation while minimum temperature at germination stage accounts for 9.4% of the yield in the study area. Binbol et al. (2006) established that climate plays an important role in agricultural productivity in the region. Climate mechanisms that are important to the region include El Nino, where over the years the Nigerian region has seen reduced rainfall, and higher temperatures and evaporation. Observed and predicted climate change can potentially influence sugarcane production in the region. The projections of the effects of regional climate change have a tendency to lower crop yields in the study area, as now obvious in the yield of sugar cane.

2.3 Water Footprint

Water footprint provides a unique methodology designed for evaluating the consumption of water resources in the practice of agricultural production (Hoekstra & Hung, 2002; Hoekstra et al., 2011). In the production of a particular product, its water footprint refers to the volume of water used to produce the particular product, measured at the point of production. Chapagain and Hoekstra (2011) defined the water footprint of crop production as “the volume of freshwater both consumed and affected by pollution during the crop production process, and it has three components: 1) green water footprint (the volume of the precipitation consumed in crop production process); 2) blue water footprint (the volume of surface or groundwater consumed in crop production process); and 3) grey water footprint (the volume of freshwater that is required to assimilate the load of pollutants during the crop production process” (Sun et al., 2012; pg 1177; para 2).

A water footprint is an all-inclusive volume of freshwater consumption that joins consumptive water use to a certain place, time, and type of water resource. Water footprint differs from the typical measure of water use, water withdrawals, because a water footprint only accounts for consumptive water use, which is water that becomes unavailable locally in the short term due to evaporation or quality decline (Doute & Fraisse, 2012). Water footprint as an indicator of water use does not only apply in the evaluation of water consumption and production. Its evaluation of water resource system can also be broadened to offer information on water utilization for decision-making (Sun et al., 2012).

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