◄UNIT 6 : CLASSIFICATION OF SOILS AND SOIL FORMATIOUNIT 8: GLOBAL DRAINAGE SYSTEMS►

UNIT 7: CLIMATE CHANGE

  • UNIT 7: CLIMATE CHANGE

    Key Unit competence
    By the end of this unit, I should be able to discuss the climate change and 
    its impact on Rwanda and the other countries
     
    Introductory activity
     1) Using internet research  and other geographical materials make a 
    research to establish relationship  between the following concepts: 
    i) Climate change and global warming
    ii) Green house phenomena and desertification 
    2) Basing on the knowledge acquired from the question 1, assess the 
    consequences of climate change on Rwanda.
    3) Which area of Rwanda is likely to experience the desertification? 
    Give reasons supporting your answer.

    7.1. Climate change: definition, causes and effects  
    Learning activity  7.1
    Study carefully the below photographs and answer the questions 
    that follow:

    1) What does climate change mean? 
    2) Explain how industries contribute to the climate change? 
    3) Describe the effects of climate change
     
    7.1.1. Definition of climate change
     Climate change refers to the long-term changes in average conditions and 
    characteristics of earth’s lower surface atmosphere resulting either from natural 
    variability or human activities that change atmospheric conditions of a region or 
    location. It is also defined as a long term change of climatic elements such as 
    temperature, rainfall, wind speed and direction, sunshine, atmospheric humidity, 
    atmospheric pressure, cloud cover over a given region of earth’s lower surface 
    atmosphere or globally. 

    7.1.2. Causes of climate change
    The causes of climate change are classified into natural causes and man - made 
    causes
    i) Natural causes of climate change 
    Natural causes of climate change include:

    Variations in the earth’s orbital characteristics
    The more elliptical orbit makes the earth to be once year in closest position to 
    the sun (Perihelion: 147 500 000 km) or in farthest position to the sun (Aphelion: 
    152 500 000 km). At the Aphelion, the earth receives the least solar energy 
    while the maximum is received at the Perihelion. 

    Volcanic eruptions
     Volcanic activity affects the climate. World temperatures are lowered after a 
    series of volcanic eruptions. This is due to the increase in dust particles in the 
    lower atmosphere which will absorb and scatter more of the incoming radiation. 
    Sulphur dioxide gas is given off during some of the eruptions. This gas remains 
    in the atmosphere for as long as three years and it reacts with water vapor 
    and forms a bright layer in atmosphere. This layer reduces the amount of solar 
    radiation reaching the earth surface by reflecting some back to universe.

    Variations in solar output 
    Sunspot activity which occurs in cycles, may significantly affect our climate. 
    Times of high annual temperatures on earth appear to correspond to periods 
    of maximum sunspot activity.  The results found from satellites measurements 
    showed a decrease of 0.1% of the total solar energy coming to the earth in the 
    early 1980s. This value was obtained over a period of 18 months. It is predicted 
    that the increase in solar output of 1% per century will contribute to the increase 
    of the global average temperatures by between 0.50C and 10C. 

    Variation of aerosols in atmosphere
     Aerosols like solid particles of varying sizes and liquid droplets which include: 
    ploughed soil cover, deserts, rocks, salt particles from seas and oceans; 
    meteoric particles, organic matter, such as bacteria, seeds, spores and pollen. 
    These particles help in selective scattering of shortwave electro-magnetic solar 
    radiation which adds varied color of red and orange at sunrise and sunset. Some 
    of the aerosols, mainly water droplets, absorb certain amount of solar radiation 
    while some amount of radiant solar energy is reflected back to the space. The 
    high concentrations of aerosols in atmosphere decrease the temperatures to 
    reach the earth surface.

    Sunspots
     Sunspots, defined as dark areas within photosphere of the sun and surrounded 
    by chromosphere, are created in the solar surface (photosphere) due to periodic 
    disturbances and explosions. These dark areas are cool areas because they are 
    characterized by 1, 5000C less temperature than remain part of photosphere. 
    The increase or decrease in number of sunspot is completed in a cycle of 
    11 years. It is believed that the energy radiated from the sun increases when 
    the number of sunspots increases and consequently the amount of insolation 
    received at the earth’s surface also increases.
     
    ii) Human causes of climate change
     Human activities have been the mostly responsible for atmospheric alterations. 
    Human activities participate highly in atmospheric pollution leading to the 
    change in composition of atmosphere. 
    The atmosphere is polluted by human activities in the following ways:

     Variations of carbon dioxide in atmosphere
     Carbon dioxide (CO2 ) is an important heat-trapping (greenhouse) gas. It 
    is released through human activities such as burning fossil fuels and gases 
    released from industries, as well as natural processes such as respiration and 
    volcanic eruptions. There is a positive relationship between the concentration of 
    carbon dioxide in atmosphere and the global temperatures: high concentrations 
    of carbon dioxide result to the rise of temperature on the earth surface while low 
    concentrations of carbon dioxide result to the lower temperatures. 

    Forest and grassland fire
     It increases the concentration of carbon dioxide in atmosphere resulting from 
    the burn of trees and grassland which are cut and put under fire for different 
    purposes.
     
    Deforestation and land use changes
     When people clear large areas of forests and grasslands for cooking or 
    construction, they reduce the main disposal system for carbon dioxide from 
    atmosphere by photosynthesis, which leading to the increase of carbon dioxide, 
    and eventually to the increase of temperature on the earth surface.
     
    Industrial developments
     Gases like methane, nitrous oxide, chlorine, bromine and fluorine are added into 
    the atmosphere through industrial activities.

    Industrial waste and landfills
     Industries which are involved in cement production, fertilizers, coal mining 
    activities, oil extraction produce harmful greenhouse gases. Also, landfills filled 
    with garbage produce carbon dioxide and methane gas contributing significantly 
    to greenhouse effect.
     
    Urbanization
    The buildings of cities increase the reflection and decrease the absorption of 
    solar radiation which would change the temperatures on the earth surfaces. The 
    urban activities participate also in increasing the concentrations of greenhouse 
    gases in atmosphere leading to the rise in temperature.
     
    Increase in Population
     It is obvious that this last two decades the people have been huge increase in 
    the population. Now, this has resulted in increased demand for food, cloth and 
    shelter. New manufacturing hubs have come up cities and towns that release 
    some harmful gases into the atmosphere which increases the greenhouse 
    effect. So, more people means more usage of fossil fuels which in turn has 
    aggravated the problem.
     
    Farming
     Nitrous oxide is one the greenhouse gas that is used in fertilizer and contributes 
    to greenhouse effect which in turn leads to global warming.
     
    7.1.3. Effects of climate change in the world (global, Africa, Rwanda)
     i) Effects of climate change in the world
    The following are the effects of climate change in different parts of the world:
    Increase in the amount of rainfall: A rise in global temperatures could lead 
    to an increase of evapotranspiration. This could eventually lead to the rise in 
    amount of rainfall.
     
    Melting of glaciers:     A rise of temperature leads to the melting of glaciers in 
    polar and mountainous regions resulting into flooding. This would cause the 
    levels of the sea to rise by 20 cm by the year 2030.

    Rise in the sea and ocean levels:     The increase in the amount of rainfall and 
    melting of glaciers leads to the increase of the sea and ocean levels destroying 

    both human and physical features at the coast.
    Increases in intensity of extreme weather: Climate change increases 
    events such as heat waves, tornadoes and hurricanes.

     The prolonged severe droughts: Some regions may experience prolonged 
    droughts caused by reduction in rainfall, which may result in aridity.

     Depletion of ozone layer: High amount of harmful ultraviolet radiation 
    increases the cases of animal and human diseases such as cancers, blindness 
    and other eye diseases.

    Occurrence of acid rain:     Acid rain is harmful to animal and human being.

    Lower crop and timber yields:     Since ultraviolet radiation slows down many 
    aspects of plant growth such as photosynthesis and germination in many plants 
    leading to low production.

    R    eduction of plankton growth:     As temperature goes beyond coral reefs 
    living standard, fish breeding and feeding patterns are disrupted.

    Decrease of agricultural production    : In some regions, the rainfall may 
    decrease, or agriculture seasons be disrupted because of climate change. 
    Some regions became drier and make soil infertile for crop production.

    City environments becoming warmer:     The increase of carbon dioxide 
    makes the temperatures to increase most in urban areas.

     Water use and long-term planning: A wetter or drier climate can affect 
    water resources planning. Water reservoirs, dams, and hydroelectric projects 
    might become useless in coming years.
     
    Spread of vector-borne diseases: Because of high temperature there can 
    be an increased range of insects.

    Acidification of oceans:     This can create a reduction in plankton, coral reefs 
    and a drop-in fishing yield.
     ii) Effects of climate change in Africa
     The following are some of the facts showing the climate change and variability 
    in Africa:
    – Melting of glaciers on the top of the highest African mountains such as 
    Kilimanjaro, Rwenzori, Kenya and Karisimbi;
    – Warming in African tropical forests has been evaluated at 0.29 °C for 
    the past 10 years and 0.1 °C to 0.3 °C in South Africa, while it ranged 
    between 0.2 °C and 0.3 °C in the Nile Basin countries;
    – Decreasing trends in temperatures; in eastern Africa, the situation has 
    been complex because they have been observed over the regions 
    close to the coast or major inland lakes and increasing in the rest of 
    the region;
    – The gradual heating, between 1961 and 2000, over the continent 
    meant more warm spells (days) and fewer cold days across Africa. 
    An increase in temperature in Sahara desert has led to the decline in 
    volume of water in Lake Chad;
    – Fluctuations of precipitation; the extent of variability is complicated and 
    exhibits more spatial and temporal fluctuations across the continent;
    – The decrease in rainfall has been registered in West Africa (between 4 ° 
    and 20 °North; 20 °West and 40 °East), by up to 20% to 40% for the 
    periods 1931-1960 and 1968-1990 respectively. A similar decline in 
    mean annual rainfall has also been observed in the tropical rain-forest 
    zone. A reduction of around 4% in West Africa, 3% in North Congo 
    and 2% in South Congo for the period 1960-1998.;
    – Increases in rainfall have been registered in different parts of southern 
    Africa (e.g., Angola, Namibia, Mozambique, Malawi, and Zambia);
    – Increase in the desertification in south of the Sahara desert;
    – Links have also been identified between the warm Mediterranean Sea 
    and abundant rain fall over the surrounding regions.
     
    iii) Effects of climate change in Rwanda
     Rwanda experiences some rainfall events that cause unexpected flooding and 
    catastrophic events such as landslides etc. These extreme events are attributed 
    to climate change. The figure below represents some effects of extreme rainfall 
    events of climate change in Rwanda.
     
    The following are effects of climate change in Rwanda:
    – Significant increase in precipitations at a rate of between 2 and 6.5 mm 
    per year over the Congo-Nile crest and the northern highlands for the 
    period of 1935–1992.
    – Floods that occurred in May 2002 caused the death of 108 persons in 
    North western regions while the one occurred in 2007 have resulted to 
    displacement of more than 456 families and destruction of hundreds of 
    hectares of crops in Bigogwe sector in Nyabihu District;
    – During September 2008 heavy rainfall accompanied by winds affected 
    8 of the 12 sectors of Rubavu district and provoked the displacement 
    of more than 500 families, caused the destruction of about 2,000 
    hectares of crops and many other infrastructures;
    – Floods reported in September 2012 in Nyabihu, Rubavu, Bugesera 
    and Kirehe districts whereby more than 1000 families were displaced 
    and their crops submerged completely;
    – The landslides and floods caused by heavy rainfall are regulary observed 
    mainly in north- western parts of Rwanda (Rulindo, Gakenke, Musanze, 
    Nyabihu and Rubavu districts). For instance, the floods which occurred 
    on 2nd and 3rd April, 2016 caused the death of 12 people, with 19 
    injured and destruction of 196 houses across the country. The floods 
    which took place in Musanze district on 20th April 2016 caused the 
    destruction of 64 houses and many hectares of crops and cattle;
    – The significant increase in mean annual temperatures of between 0.036 
    and 0.066 °C per year for the period of 1961-1991;
    – Since 1902, a number of famines following prolonged droughts 
    episodes have been registered in Rwanda notably in eastern and 
    south-eastern regions;
    – More occurrences of lightning combined with the thunderstorms in 
    2013 caused 12 deaths in Karongi, 12 in Rubavu, 4 in Rusizi and 5 
    death in Rutsiro districts, respectively. The same districts suffered from 
    the same extreme weather events which were reported to cause 15 
    deaths in 2015 (January-October) with 30 people injured.

    Application activity 7.1
     1) Identify the areas of Africa that are susceptible to face the climate 
    change challenges? 
    2) Describe the effects of climate change in Eastern and Western 
    provinces of Rwanda.
     
    7.2. Global warming and the green house phenomena 
    (definition, causes and the effects)
    Learning activity  7.2
     1) Use different resources to find the meaning of the following:
     i) Global warming
     ii) Green house phenomena
    2) Explain the reasons of practicing greenhouse farming.

     7.2.1. Definitions of global warming and greenhouse 
    phenomena
    These two phenomena of global warming and greenhouse are related but are 
    different.   

    i) Global warming
     Global warming refers to the gradual rise in world temperatures. This is a gradual 
    increase in the average temperature of the earth›s atmosphere and oceans due 
    to increase in the amount of carbon dioxide. The increase in the amount of 
    carbon dioxide leads to greenhouse effect. It is a change that is believed to be 
    permanently changing the earth›s climate. An increase in greenhouse gases 
    increases the greenhouse effect which in turn increases the global warming. 
    In the last 100 years, the mean surface temperature on earth has increased by 
    0.5 °C.  

    i) Greenhouse effect 
    The greenhouse effect is a phenomenon in which the atmosphere of a planet 
    traps radiation emitted by sun. It is caused by gases such as carbon dioxide, 
    water vapor, and methane that allow incoming solar radiation to pass through 
    but retain heat radiated back from the planet’s surface. 

     7.2.2. Causes of global warming and green house 
    phenomena
    The following are the causes of global warming and green house phenomena:
     
    1) Human factors 
    Human activities produce various gases ejected in the atmosphere that are 
    responsible for the global warming. These activities are destroying earth at fast 
    rate: the emission of carbon dioxide from industries and vehicles, the burning 
    of fossil fuels, cutting of trees and forests to build some new buildings and new 
    malls, dumping of trash everywhere and not even recycling it, excessive use of 
    the plastics and smoke from factories. All the activities performed by human 
    beings are the major factors for gases that pollute the air and warm up the earth. 
    These may contribute to the destruction of the ecological balance of the nature 
    leading to the global warming.

    Burning of fossil fuels
     Fossil fuels are burnt on day-to-day basis. This activity produces large 
    percentage of gases such as carbon, petroleum, coal and many other different 
    gases which are emitted in earth’s atmosphere. Carbon dioxide being one of 
    gases with greenhouse effect is provided in excess in our atmosphere in far 
    greater quantity in comparison with other gases produced by human activities.

    Use of chemical fertilizers
    The use of the artificial chemicals for crops has become one reason for the global 
    warming. These chemicals are dangerous to the earth as well as to the human 
    beings. These fertilizers are rich in the nitrogen oxide which is more dangerous 
    than the carbon dioxide. Those oxides of  nitrogen destroy ozone layer even 
    faster than other greenhouse gas and hence let harmful ultraviolet rays enter 
    atmosphere thus making earth warm and leading to the global warming.

     Industrial advancement
     More and more different industries and factories are set up in modern world to 
    meet needs of the human beings. These factories need large amount of fuels like 
    some coal, petroleum for power generation and electricity required by machines 
    to work. Burning of these fuels also releases large amount of the carbon dioxide 
    which absorbs harmful radiations from sun making it warm, hence increasing 
    global warming.  

    Deforestation
    The mass removal of trees, called deforestation, also affects the amount of 
    carbon dioxide in our atmosphere. Forests around the world are being cleared 
    for cultivation, mining, building, roads building, grazing cattle, etc. As they grow, 
    trees take in carbon dioxide. When trees are removed, the carbon dioxide that 
    they could have removed from the atmosphere is left. Cut-down trees are often 
    burned. Burning produces more carbon dioxide.  If the trees are cut, plants will 
    not be able to produce oxygen and concentration of the carbon dioxide will 
    increase. Increase of the carbon dioxide in air is very harmful for the human beings 
    and also disturbs water cycle and hence total imbalance of our ecosystem. So 
    being one of greenhouse gases it will lead to the global warming.

    Air pollution
    The harmful gases emitted from vehicles and the factories and greenhouse gases 
    cause some pollution in the air and these gases get captured in atmosphere. 
    The smoke gather up in atmosphere forming some clouds full of harmful gases 
    which later fall as the acid rain which destroys plants. Plants provide us with 
    oxygen and if they die level of carbon dioxide will increase in atmosphere which 
    is known as a harmful gas. These gases emit heat which increases temperature 
    of earth, hence causing global warming.
     
    2) Physical factors 
    Volcanic eruptions
    Volcanic eruptions are also among the causes of global warming. These eruptions 
    contain the dust particles and gases like the sulfur dioxide which stays in the 
    atmosphere for years and blocks the sunlight from reaching surface of earth 
    making it somewhat cool. These dust particles affect balance of atmosphere 
    and become contributing factor of the global warming. 

    Depletion of ozone layer
     Depletion of ozone layers is an important factor that causes global warming. 
    The ozone layer is known as the layer outside the atmosphere which protects 
    surface of the earth from harmful ultra-violet and the infrared radiations causing 
    some dangerous diseases like the skin cancer. Ozone layer depletion is one 
    of causes of the global warming; entering of the harmful gases which helps 
    in heating up the earth but other greenhouse gases like the carbon dioxide 
    and methane that helps in heating up and tears up ozone layer making a hole 
    called “Ozone hole”. So, ozone layer depletes due to these gases which allow 
    ultra violet radiations to enter the earth’s atmosphere making it more warm than 
    normal and also affects temperature leading to the global warming. 

    7.2.3. Impact of greenhouse process on global warming  
    Greenhouse effect is a process in which the atmosphere of the earth traps 
    some of the heat coming from the sun and fails to radiate, making earth warming. 
    This is due to the burning fuels, cutting of trees, concentration of the heat on 
    earth is increased to some abnormal levels making the greenhouse effect as 
    one of the major causes of the global warming. Carbon dioxide, nitrous oxide 
    and methane are the greenhouse gases which help to keep earth warm. It is 
    natural phenomenon that takes place with adequate concentrations of some 
    greenhouse gases. When concentration of these gases rises then they disturb 
    climatic conditions, thus making earth warmer. These gases are not able to 
    escape and that causes the worldwide increase in temperatures. So balance of 
    the carbon dioxide and some other gases should be maintained so that it does 
    not become major reason for the global warming.

    A    pplication activity 7.2
     1) Explain why causes of climate change and green house differ in rural 
    and urban areas. 
    2) Among the effects of climate mentioned above, which ones do you 
    observe in your local environment?
     3) Referring to the greenhouse phenomenon, describe the advantages 
    and disadvantages of the farming practiced in greenhouse.
     
    7.3.  Adaptation measures and mitigation for the climate change  
    Learning activity  7.3
    In your local environment, identify any evidence of climate change and 
    propose sustainable strategies to deal with it.
     
    7.3.1. Adaptation measures for climate change 
    Adaptation for climate change refers to measures and strategies taken to 
    cope with climate change and variability. These measures vary from one domain 
    to the other like agriculture, livestock keeping, tourism, public health and 
    water management; from one climatic region to the other as dry, wet, hilly, flat, 
    depression, mountains, floodplains; from season to season as in dry and wet 
    seasons; and across diverse actors as private, public, national, international, 
    NGOs, local communities. Hence, adaptation measures are many and are not 
    homogeneous. Some of them are briefly described below: 

    Maintaining current ecosystems wherever possible:     This implies 
    strengthening, extending and in some cases refining global protected area 
    networks to focus on maintaining large blocks of intact habitat with a particular 
    emphasis on climate change.

    Agro-forestry:     This is a land-use system that incorporates trees in food crop 
    fields. In other words, it is a combination of agriculture and forestry for more 
    diverse, profitable, productive and sustainable land use. 

    Progressive and radical terracing    : This is used to reduce runoff, soil 
    erosion and landslides. At the same time, terracing helps to improve soil 
    quality and moisture retention, especially in steep areas.

    Soil fertility conservation:     Practices like the use of manure, mulching, 
    planting of leguminous crops help to improve soil fertility by increasing the 
    micro-organism composition in the soil.

    Seed and grain storage    : This involves collecting seeds and grains from 
    farmers at post-harvesting season and releasing them within the timely agreed 
    periods. 

    The use of pesticides:     It is a wide range use of compounds such as 
    insecticides, fungicides, herbicides, rodenticides, molluscicides, nematicides, 
    plant growth regulators and others to control pests, insects, fungi, weeds, 
    bacteria, rodents, all of which are harmful to crops. 

    Ecological pest management:     This is the use of natural enemy dynamics 
    or environmental positioning (e.g. crop shading) to eliminate or reduce the 
    presence of pests.

    The use of improved seeds and species:     This is vital to improve crop 
    productivity. 

    Crop varieties and diversification: This measure consists of integration of 
    different varieties of crops and hybrids of a particular crop. Multiple cropping 
    aids in replenishing the soil and maintaining its fertility by ensuring that there 
    is a constant balance of nutrients by decreasing dependence and saturation 
    of any one product.

    Land use consolidation programmes:     This encourage farmers with 
    adjacent lands to grow the same crop. This facilitates the provision of inputs 
    (e.g. seeds and fertilizers), post-harvest activities (e.g. driers, seed and grain 
    storage facilities) and safer and faster transport of agricultural products. 

    Rain water harvesting:     It is the practice of collecting and storing rainwater 
    from rooftops, land surfaces or rock catchment areas for different use.

     Irrigation like drip irrigation is a practice based on the constant application 
    of specific and controlled quantity of water to the crops. The system uses 
    pipes, valves and small drippers or emitters that transport water from the 
    sources (i.e. wells, tanks and reservoirs) to the root area and applying it in 
    controlled quantities and pressure specifications while Sprinkler irrigation 
    involves spraying the crops with water using sprinklers in a manner that 
    resembles rainfall.

    Wastewater use    : It forms a reliable source for crop irrigation and a positive 
    way to dispose of sewage water. Whereas wastewater contains a lot of 
    nutrients on the one hand, it carries pollutants like micro and macro organic 
    and inorganic matters that potentially pose hazards to human health, the 
    environment, crops and soils, on the other.

    Biotechnology of crops    : It involves the practical application of biological 
    organisms, or their sub-cellular components in agriculture and livestock. The 
    techniques currently in use include tissue culture, conventional breeding, 
    molecular marker-assisted breeding and genetic engineering. 

    Barrier crops:     These are crops that are used as a cultural control strategy 
    for reducing the spread of pests and diseases to the most vulnerable crops. 
    These crops provide benefits over “hard infrastructure” in a number of ways: 
    first, they offer a natural form of protection; second, they contribute to the 
    biodiversity and often soil improvement; third, they can provide an added 
    source of food provisions or income and, finally; they can play a determinant 
    role in soil erosion reduction. 

    Integration of meteorological information in agriculture:     It is used to 
    develop early warning systems, crop monitoring and disaster management. 

    Training farmers: By offering short courses, seminars and group discussions 
    on the impacts of climate changes and on various ways of adaptation.

    Facilitating the farmers: this consists of facilitating farmers to access 
    capital that they need to purchase seeds, installation of tube wells, drilling 
    of pumping sets, chemical fertilizers, plant protection chemicals, tractors, 
    harvesters, threshers and other accessories.
     
    Development of infrastructure: This concerns the improvement of 
    transport networks, electricity and marketing facilities which use to be 
    affected by climate change phenomena to promote a sustainable livelihood 
    of population.

    Development of agricultural institutions:     The institutions such as 
    universities provide experts and researchers who offer critical services 
    like assessment, promotion of agricultural and livestock innovations and 
    dissemination of research findings to agronomists and farmers at all levels.
     
    7.3.2. Measures for mitigating the climate change
     Mitigation measures for climate change consist of actions to limit the magnitude 
    and the rate of long-term climate change. Climate change mitigation generally 
    involves reductions in human (anthropogenic) emissions of greenhouse gases. 
    Anthropogenic greenhouse gases include carbon dioxide (CO2), methane 
    (CH4), Nitrous oxide (N2O) and a group of gases referred to as halocarbons. 

    The following are mitigation measures for climate change:
     Storing and reducing carbon dioxide: Carbon dioxide can be captured and 
    stored, but also it can be reduced. Carbon dioxide Capture and Storage (CCS) 
    is a process consisting of the separation of CO2 from industrial and energy 
    related sources, transport to a storage location and long-term isolation from the 
    atmosphere. Conserving electricity is one strategy to reduce CO2. 
    When we conserve electricity, we reduce the amount of fossil fuel that must be burnt. One 
    way to save fuel is to change daily activities that rely on energy from burning 
    fuel.

    Use of energy that reduces the atmospheric pollution:     The use of 
    renewable energy supply technologies, particularly solar, wind, geothermal and 
    biomass are recommended to reduce the atmospheric pollution. Renewable 
    energy systems such as hydro-electricity can contribute as well to the security 
    of energy supply and protection of the environment.

    Reduction of the energy use in buildings:     Cooling energy use in buildings 
    can be reduced by different measures, for example reducing the cooling load by 
    building shape and orientation. 

    Land-use management:     Forest land, cropland, grassland, wetlands, 
    settlements have to be well managed by fighting against any threaten to them. 
    Changes in land use may result in net changes in carbon stocks and in different 
    impacts on water resources. 

    Crop land management:     The use of agricultural practices which promote 
    the conservation of water, and its quality. There is a need for improved crop 
    and grazing land management to increase soil carbon storage; restoration of 
    cultivated peaty soils and degraded lands.
     
    Afforestation and reforestation: The increase of number of trees helps to 
    capture the CO2 and decreases the flow of water from catchments.

    Solid waste management and waste water treatment:     Controlled landfill 
    (with or without gas recovery and utilization) controls and reduces greenhouse 
    gas (GHG) emissions but may have negative impacts on water quality in the 
    case of improperly managed sites.

    Application activity 7.3
     1) If you were the Director General of REMA, demonstrate the adaption 
    measures to climate change in Rwanda.
     2) Suppose that you are a manager of a big industrial complex, describe 
    the strategies to mitigate climate change.
     3) Explain the process by which the use of refrigerator contributes to 
    climate change.
     
    7    .4. Desertification (definition, causes, effects)
     Learning activity  7.4
     Study the photograph below and answer the questions that follow:
     1. Explain what happen in the area shown in the photograph.
     2. Explain how climate change contributes to desertification.
     3. Referring to the figure below, describe the challenges that face 
    people living in desert areas.

     
    7.4.1. Definition of desertification
     Generally, desertification is described as the turning of the land into desert. It 
    is the process by which the land undergoes degradation from which a relatively 
    dry land region becomes increasingly arid, typically losing its bodies of water as 
    well as vegetation and wildlife. Desertification is caused by a variety of physical 
    factors, mainly the climate change and human activities.

    7.4.2. Causes of desertification
     Desertification is caused by a combination of factors that change over 
    time and vary with location. These include the following: 
    Less rainfall (total amount) and increased drought (frequency and 
    intensity) lead to drought of rivers and water bodies and decrease in protective 
    vegetation cover. 

    Global warming:     It causes higher temperatures and increased 
    evapotranspiration. This reduces condensation and leads to shortage of 
    rainfall.

    Population growth:     The effect of this is the over-cultivation which reduces 
    soil fertility and leaves the soil exposed to erosion.   

    Deforestation:     An increased demand for cultivation land, wood for cooking, 
    heating, building, increases the risk of soil erosion. 

    Poor crop cultivation practices    : Some farmers do not know how to use 
    the land efficiently. Farmers may essentially strip the land of everything that 
    it has before moving on to another plot of land. By stripping the soil of its 
    nutrients, desertification becomes more and more of a reality for the area that 
    is being used for farming.

    Urbanization and other types of land development:     Development can 
    cause people to go through and kill the plant life. It can also cause issues 
    with the soil due to chemicals and other things that may harm the ground. As 
    areas become more urbanized, there are less places for plants to grow. This 
    can contribute to the process of desertification.

    Soil erosion:     The losses of the top soils and vegetation leads to the 
    desertification.

    Climate Change    : Climate change plays an important role in desertification. 
    As the days get warmer and periods of drought become more frequent, 
    desertification becomes more and more eminent. Unless climate change is 
    slowed down, huge areas of land will become desert; some of those areas 
    may even become uninhabitable as time goes on.

    Over exploitation of the land of resources:     If an area of land has natural 
    resources like, oil, or minerals, people will come in and mine it or take it 
    out. The removal of resources is usually associated with the striping of the 
    soil and depletion of nutrients. Consequently, plants are died and from there 

    starts the process toward becoming a desert biome as time goes on.

    Natural disasters: There are some cases where the land gets damaged 
    because of natural disasters, such as natural fires, drought, floods, and 

    earthquakes.

    Rise of salinity: In the soil which causes the vegetation to be stunted.
    Overgrazing: If there are too many animals that are overgrazing in certain 
    spots, it is difficult for the plants to grow back. Biomes are affected and lose 

    their original vegetation.

     7.4.3. Effects of desertification
     The following are the major effects of desertification:
     Farming becomes unproductive: If an area becomes a desert, it’s almost 
    impossible to grow substantial crops there without special technologies. 
    This can cost a lot of money to try and do so as many farmers will have to sell 
    their land and leave the desert areas.

    Hunger (famine):     Without farms in these areas, the food that those farms 
    produce will become much scarcer. The people who live in those local areas 
    will be a lot more likely to try and deal with hunger problems. Animals will also 
    go hungry due to food shortage.

    Flooding:     Without the plant life in an area, flooding is much more eminent. 
    Some huge rivers cross deserts which experience a lot of flooding because 
    there is nothing to stop the water from gathering and going all over the place. 

    Poor water quality:     If an area becomes a desert, the water quality is going 
    to become a lot worse than it would have been otherwise. This is because 
    the plant life plays a significant role in keeping the water clean and clear.

    Overpopulation of the new areas    : When areas start to become desert, 
    animals and people will go to other areas where they can actually thrive. This 
    causes overcrowding and overpopulation, which will, in the long run, end up 
    continuing the cycle of desertification that started this whole thing anyway.

    Poverty:     All of the issues that are described above (related to the problems 
    of desertification) can lead to poverty if it is not kept in control. Without food 
    and water, it becomes harder for people to thrive, and they take a lot of time 
    to try and get the things that they need for their subsistence.

    Acceleration of desertification    : The increased frequency and severity of 
    droughts resulting from projected climate change is likely to further accelerate 
    desertification.

    Involuntary migration:     Rural population affected by the effects of climate 
    change, especially the drought or aridity migrate towards different areas. This 
    may also lead to rural exodus. 

    Shortage of drinking water and water to use for other purposes: 
    This is where overpopulation causes pressure to exploit dry lands for farming. 
    These marginally productive regions are overgrazed, the land is exhausted, 
    and groundwater is over drafted.
     
    Application activity 7.4 

    Observe carefully the picture below and answer the questions that follow:

     i) Referring to the factors of desertification discussed above, describe 
    the causes of the above phenomenon.
    ii) Explain the effects of drought to the people living in such area.
     iii) Considering the physical conditions of Rwanda, suggest the districts 
    in which the above phenomenon is likely to happen and the strategies 

    to limit this problem.

    Skills Lab
     Provide specific examples and analyze how human activities affect climate change.

    End unit assessment
     1. Compare the factors that can cause the climate change in China 
    and Rwanda.
     2. Explain the causes of climate change in developed and developing 
    countries.
     3. The World needs to develop at high rate with its industrialization 
    processes which is among the most causes of greenhouse effects. 
    Suggest the mitigation measures for climate change in this regard. 
    4. The world is facing the problem of climate change and this is 
    substantially leading to the problem of desertification.
     a. Indicate the most affected areas by that problem? 
    b. Suggest the sustainable strategies to address the problem of 

    desertification.

    ◄UNIT 6 : CLASSIFICATION OF SOILS AND SOIL FORMATIOUNIT 8: GLOBAL DRAINAGE SYSTEMS►