Population growth, though a source of development is commonly regarded as one of the most dreadful cause of environmental degradation. Population can be defined in terms of a particular section, group, or type of people or animals living in an area or country. Population growth has been defined in diverse ways by various authors and institutions (Wikipedia1). In this context, population growth refers to the growth of human population in the world in terms of how the number of individuals in a population increases over time.

According to The United International Strategy of disaster reduction, environmental degradation is the reduction of the capacity of the environment to meet social and ecological objectives and needs. (UNISDR, 2009)
A report by the United Nations population Division 1998, records that the world population has doubled since 1950. About 90 million babies are born each year. At this rate, by the year 2050, global population will reach 10 billion. The current world population is on average very young and has many years of reproductive life ahead. Because of this the population will grow even if the fertility rates seem to decrease. The population growth takes mostly place in developing countries. These countries are in charge of 90 percent of current population growth. It has been estimated that by the year 2025 even 84 percent of the world’s people will live in developing regions.
Most estimates for the carrying capacity of the earth is between 4 billion and 16 billion. Depending on which estimate is used human population may or may not have already occurred. The main concern therefore is the rising population and its auspicated effects on the environment especially in the developing Nations where we have a high population growth rates and poor modes of food production.
The environment and key natural resources in most African countries have been increasingly threatened by escalating and unsustainable pressures from fast-growing populations (UNEP, 1999). Nations with high population growth are often not able to produce enough goods to meet their basic needs of their inhabitants.

An expansion of the production of various goods seems necessary in order to sustain the population. However an increase the amount of goods produced may aggregate environmental problems; in particular if the less developed countries follow the pattern of Development of Western Industrialized countries.
The demand placed on the environment to provide resources for increased human activities such as industrialization, exploitation of water and land resources and Urbanization, and absorption of wastes steadily increases and long term effects is the simultaneous degradation of the environment.
The aim of this paper is to examine how increased world population through human beings change of life degrades the environment. Man degrades the environment through his direct or indirect acts that include:-
Ø  Altering and disturbing the natural resources
Ø  Through intensive  Agriculture practices
Ø  Development of cities (Urbanization)
Ø  Rapid growth and expanding off industries

Urbanization refers to the general increase in population and the amount of industrialization of a settlement. It includes increase in the number and extents of cities. It symbolizes the movement of people from rural areas to urban areas.
Urbanization happens because of the increase in the extent and density of urban areas. The density of population in urban areas increase because of the migration of people from less industrialized regions to more industrialized areas
Causes of urbanization
Urbanization usually occurs when people move from villages to cities to settle, in hope of a higher standard of living. This normally takes place in developing countries
In rural areas, people become victims of unpredictable weather condition such as drought and floods, which can adversely affect their livelihood. Consequently these people move to cities in search of better life. This can be seen in areas like Budalangi, Kano plains, Tana Delta where these people move to Kisumu, Nairobi, and Mombasa etc to escape poverty.
Cities in contrast, offer opportunities of high living and are known to be places where wealth and money are centralized
Most industries and educational institutions are located in cities whereas there are limited opportunities within rural areas. Thus further contribute to migration to cities
Environmental impacts of urbanization
Due to factors such as paving over formerly vegetated land, increasing number of residences, and high-rise apartments and industries temperatures increases drastically.
Air pollution
Factories and automobiles are symbols of urbanization. Due to harmful emission of gases and smoke from factories and vehicles, air pollution occurs.
Most of the ambient air –pollution in urban areas comes from the fossils fuel industry, motor vehicles, heating and electricity generation. In some cities the main air polluter is the domestic heating which results into indoor air pollution. Indoor air pollution may pose an even greater hazard for human health. Cooking and heating with wood, crop residues, animal dung and low quality coal produces smoke that contain dangerous particles and gases which may include various toxic and carcinogenic chemicals, heavy metals, trace organic chemicals and fibres, photochemical pollutants, lead,carbon monoxide, which are much more harmful to human health (HABITAT 1996). When fuels such as these are burned indoors, using inefficient stoves and poor ventilation, they can cause tuberculosis, other respiratory diseases and blindness (Mishra, Rether ford and Smith,1999). In fact, indoor air pollution from cooking and heating with unsafe fuels has been designated by the World Bank as one of the four main environmental problems in developing countries.
Traffic: almost all cities have changed to motorized road vehicles, which has increased the use of fossil fuels and increase in green house- gas emissions. The explosive growth in the number of road vehicles is a big problem in many cities. Many city centers have major difficulties trying to cope with the chaotic automobile traffic. The traffic jam is extremely bad in many cities and transport traffic in the city area at least during rush hours is very slow. The pollution is high due to constant traffic and cause respiratory diseases to city habitants (HABITAT 1996)
Water and drainage systems
When urbanization takes place, water cycles changes and cities have more precipitation than surrounding areas. Due to damping of sewage from factories in water bodies, water pollution occur which can lead to outbreak of epidemics.
The lack of sanitation and sewage treatment is the biggest factor regarding water pollution. Local water bodies are used as dumping ground for untreated water from urban areas and industries. For example in Bangkok 90 percent of industrial wastes including hazardous chemicals are discharged without treatment (UNEP 1999).
Many rivers in developing countries are more like open sewers than rivers. Most of the centers in these regions do not have drains or even services to collect the garbage. The cities that are close to the coast often dump untreated sewage to the sea. Most of the coastal cities have serious problems with dirty, contaminated beaches and water which is a serious health risk to the bathers and for the whole city (HABITAT 1996)

Habitat destruction and loss of biodiversity
To make an area urbanized, a lot of forested areas are destroyed. Usually these areas would have been habitats to many birds and animals
Population growth leads to expanding human settlements and increasing demand for food, fuel and building materials. Modernization of agriculture also threatens potentially valuable local crops.
Such development programmes such as creating reservoirs, mining, forest clearing, lying of communication and transport networks etc. I t is estimated that in the worldwide perspective slightly over1000 animal species and sub-species are threatened with extinction rate of one per year, while 20000 flowering plants are thought to be at risk (Compendium of Environment Statistics 2000)

Rapid population growth has outstripped the ability to deliver adequate services such as education, health care, safe water, sanitation, and waste removal. The increased population exerts pressure on existing facilities and even the ecosystem since it’s beyond the carrying capacity of these facilities hence calling for expansion or creation of new facilities to cater for increased population. Growing population is one of the main forces driving a country’s overwhelming environmental challenges.
One of the major problems brought about by increase in population is settlement.  Population growth affects migration and settlement patterns and their relationships to the physical environment.  As population increases, settlements sprawl, and take over forested and agricultural land, fragmenting and degrading remaining natural areas. The clearing of forested to pave way for settlement impacts the environment negatively causing degradation. The cleared environment paves way for soil erosion as there are no trees to hold the soil together; this in turn causes pollution of the air when windy and pollution of water bodies during rainy season hence affecting aquatic life and human health. Clearing of the trees also causes loss of biodiversity. Some plant and species are lost hence affecting the ecosystem balance.
Trees act as windbreakers and clearing the forest will mean no windbreakers. It will also lead to destruction of water catchment areas. The medicinal value of the tress will be lost by destruction and there will be increased of carbon dioxide in the atmosphere as there will be no carbon sink, this will lead to global warming causing forest fires, skin cancers and rise in sea levels causing flooding resulting to displacement of people and coastal erosion.
Taking up of agricultural land to put up settlements will reduce arable land hence reduce food production and therefore leading to food insecurity.
Increase in population makes it difficult for a nation to plan; it leads to increased poverty levels, low life expectancy and high infant mortality. The pressure from increasing population is a major hindrance to sustainable development hence a country remains under developed.
Ongoing rural to urban migration, high natural birth rates, and poor or Inappropriate country’s planning conspires to continue degrading the environment and this has impacts on human health and the economy. For the country to achieve the MDGs progress must be made, an important target is stabilizing the fertility rate as recommended by the Population Policy for Sustainable
Development (CBS 2004).  The country can achieve more sustainable land use if it combines planning and development with environmental management.

Agricultural impact is such direct on the environment because it involves man manipulating the environment to gather for his needs/food. Since time in memorial man has been dealing with farming. With the increased population man has been force to clear more land to gather for the increased needs of his family.
The era of Agricultural revolution cleared fast lands to pave way for the green revolution. Agricultural revolution cleared 10% of the earth’s land surface of either grass or trees so that it could be ploughed planted to crops.
Agriculture has changed dramatically, especially since the end of World War II. The world population has shot from 370million after the Great Famine and the Black Death in Britain in 1350 to 7 Billion in 2012 March. The sharp increase in worlds population demands that more land should be brought under Agricultural use or use intensified farming methods to increase food production this in turn causes harm to the environment either directly or indirectly.
Today the 7 Billion people cultivate over 40% of the worlds land and .Total farmland has been increasing drastically since 1992 to 2002 the Agricultural land increased by 5 Million  Hectares
Of the total 13 Billion hectares of land area on Earth, Cropland accounts for 11% ,pastureland 27%, Forerstland 32%, urban land 9%the rest 21% unsuitable for crop farming.(World watch Institute http://t.co/uOQdMqrp )
Increased population through Agriculture impacts on Environmental degradation in the following ways;
        i.            Burning of forests to create new lands for Agriculture
      ii.            Use of pesticides and herbicides.
    iii.            Soil degradation and pollution
    iv.            Increased pressure on Arable land
Burning of forests to create new lands for Agriculture
Man is constantly colonizing new lands to get food for the increasing population. Burning includes human-initiated burning of vegetation for land clearing and land-use change as well as natural, lightning-induced fires. Scientists estimate that humans are responsible for about 90% of biomass burning with only a small percentage of natural fires contributing to the total amount of vegetation burned. Man is forced to clear new lands by burning the vegetation down to get more land burning vegetation releases large amounts of particulates (solid carbon combustion particles) and gases, including greenhouse gases that help warm the Earth. Greenhouse gases may lead to an increased warming of the Earth or human-initiated global climate change. In the long run the cleared forests which used to Act a carbon sinks are no more and this leads to increased levels of carbon in the atmosphere.
Use of pesticides and Herbicides for Agriculture
The increased population is always forced to use pesticides herbicides and fungicides to reduce the number of competitors in the tropical level so that food production is maximized.during their application they also affect non-target plants and animals. Repeated application leads to loss of biodiversity. Many pesticides are not easily degradable, they persist in soil, leach to groundwater and surface water and contaminate wide environment. Depending on their chemical properties they can enter the organism, bioaccumulation in food chains and consequently influence also human health.
The French incident in two French Caribbean islands, Martinique and Guadeloupe, which were heavily contaminated by pesticide chlordecone after several decades of its spraying on bananas plantations. Initially, the use led to higher crop yields but each season more chlordecone was required to achieve the same results. As a consequence, this tropical paradise with about 800,000 inhabitants now faces an environmental disaster with far-reaching ecological, economical and social impacts.

Water contamination is one of the most affected component of the ecosystem when it comes to use of Pesticides.
Pesticides can get into water via drift during pesticide spraying, by runoff from treated area, leaching through the soil. In some cases pesticides can be applied directly onto water surface e.g. for control of mosquitoes. Water contamination depends mainly on nature of pesticides (water solubility, hydrophobicity), soil properties, weather conditions, landscape and also on the distance from an application site to a water source. Rapid transport to groundwater may be caused by heavy rainfall shortly after application of the pesticide to wet soils. (pesticide action Network Europe 2008)
Soil micro-organisms play a key role in soil. They are essential for maintenance of soil structure, transformation and mineralization of organic matter, making nutrients available for plants when we are using pesticides we harm and kill this micro-organism by either deforming them or completely whipping them out of the ecosystem
Soil degradation and Pollution
All the actions that man venture into revolve around the crust. Man got direct impact on the soil and he causes stress to it by application of fertilizers, fungicides, overgrazing and contact cultivation. All this activities man venture into so that he can get food for the increased population not knowing that he/she is harming the environment greatly
Pesticides enter the soil via spray drift during foliage treatment, wash-off from treated foliage, release from granulates or from treated seeds in soil. Some pesticides such as soil fumigants and nematocides are applied directly into soil to control pests and plant diseases presented in soil. Fertilizers are also applied direct to the soil.
Increased pressure on Arable land
The geometric rise in human population levels during the twentieth century is the fundamental cause of the loss of biodiversity. It exacerbates every other factor having an impact on both Terrestrial (Grassland, mountain, Forest and Desert ecosystems) and Aquatic ecosystems, It has led to an unceasing search for more arable land for food production, livestock grazing, for wood for fuel, construction, and energy.
Balmford, et al., (2001) have demonstrated that human population size in a given tropical area correlates with the number of endangered species, and that this pattern holds for every taxonomic group. Most of the other effects mentioned below are either consequent to the human population expansion or related to it.

o   Inadequate fresh water for drinking as well as sewage treatment and effluent discharge.
o   Depletion of natural resources especially fossil fuels.
o   Increased levels of air pollution , water pollution, Soil pollution, noise  pollution,
o   Deforestation and loss of ecosystem that sustain global atmospheric oxygen and carbon dioxide  balance. About 8 million hectares of forest are lost every year.
o   Changes in atmospheric composition and consequent global warming.
o   Irreversible loss of arable land and increase in desertification.
Mass species extinction from reduced habitats in tropical forests due to slash –and- burn techniques that are practiced by shifting cultivators; especially in countries with rapidly expanding rural population present extinction rates may be as high as 140,000 species lost per year. As of February 2011 IUCN Red List, a total of 801 animal species having gone in recorded history.
Stealing of natural resources to survive conflict over scarce resource. The resources to be considered when evaluating whether an ecological niche is over populated include clean water, clean air food shelter and warmth.
The demands  placed on the environment to provide resources for human activities and to absorb wastes have grown steadily with rising population and increasing per capita consumption. Currently the highest fertility rates are found in countries suffering from poverty ,food insecurity and natural resource degradation.
Given that many natural resources  such as many natural resources( such as water, soil, forests  and fish stocks) are already being exploited to or beyond their limits in at least some regions. The efforts required to meet the needs of additional 300million people will be immense.
Globalization of population movements is needed like movement of capital and free trade in goods and services through WTO, for people to live and work wherever they like. This is the one change that allow optimization of the population  to environmental carrying capacity and  a rapid reduction in economic and solid disparities between countries.

Industrialization was a key component that man discovered in the mid 18th Century. The advent of Industrial revolution tremendously reformed most sectors in the world and it made work efficient, created employment and also made life comfortable. The second phase of industrialization begun in the 1860-1914. The second phase of industrialization was characterized by a rapid expansion of industries that developed because of new sources of energy hydroelectricity and oil.
The change in industrialization system was prompted by the increased demands of the public due to the growing population. The world population had been increasing steadily from the onset of Industrial revolution and there was need to seek for improved of production and acquiring of goods and services. During the onset of industrial revolution there was an increase in population due to increased food and diet.
 During the Agricultural and Industrial Revolutions, the life expectancy of children increased dramatically. The percentage of the children born in London who died before the age of five decreased from 74.5% in 1730–1749 to 31.8% in 1810–1829. Between 1700 and 1900, Europe’s population increased from about 100 million to over 400 million. (Wikipedia2)
The shift from the 1st phase (coal and steam era) to the 2nd phase (electricity era) coincides with the British colonization of foreign lands where they acquired many raw materials that needs to be processed in large numbers.
However, industrialization has got a serious effect on the environment while it strives to meet the needs of the growing population. Man through its agent (Industries) contribute to more than 50% of the Environmental degradation when he/she is trying to fetch raw materials, build industries and dispose waste products. The final effect on the environment will include:-
Rapid Industrialization versus Air Pollution
Air pollution involves the release of chemicals and particulates into the air, and it can cause problems varying from difficulty breathing to contamination of crops. The increased rate of industrialization poses a major threat to the air quality. Most the industries use environmentally unfriendly sources of energy like fossil fuels, coal, wood fuel and others that releases high levels of Oxides to the environment. Considering their sources of energy the industries that use wood fuel contribute so much in logging. The indirect impacts will be the releases of carbon to the atmosphere causing a significant increase in the Green houses gases which causes global warming. In extreme cases, these gases may cause river, lakes and sea levels to rise. This means that, as the globe continues to experience global warming, chances of flooding increases. The worst pollutant in low lying areas is Smog. Where smog is produced abundantly, air quality deteriorates especially during hot weather, and it is during this period that asthma cases rise. Industries associated with massive smog emissions are those that operate in manufacturing sectors. Example of the Donora Valley in Pennsylvania 1948.
The highest probable Top emitters of green house gases into the atmosphere include; Power generation industries are major causes of global warming. According to the year 2000 estimates, these industries emit more than 8000teragrams of carbon dioxide, and 3teragrams of methane. In total, this industry alone accounts for 31% of greenhouse gases emitted annually. Second on the list of industries causing global warming is the refineries. This industrial sub sector emits more than 5000teragrams of carbon dioxide and 8teragrams of methane. Refineries alone accounts for 15% of greenhouses gases emitted per year. Third on the list is the road sector. As countries continue to develop, automobiles no longer become luxuries, but necessities. By the year 2005, the vehicles emissions accounted for almost the same percentage as the refineries (15%) other contributing sectors are; coal mining and processing, oil extraction and refining, international shipping, rail and non road transportation and bio fuel production sectors (socyberty.com)
Industrialization and Land Pollution
The industrial revolution brought with it some lucrative and convenient ways of handling the Land. The Agricultural revolution intensified farming through use of inorganic fertilizers and mechanization. Modern agriculture has embrace the idea of going “green”, and has instead opted for inorganic means, has opposed to the ancient organic ways of growing crops. The key issue why the world is headed to an inorganic direction is to satisfy the growing population in terms of food supply.
Industries are the key players in production of Inorganic substances; fertilizers, pesticides and fungicides. The industries are also linked with polluting the crust through releasing of poisonous substances whether by accident or as a way of disposing them. These industries produce on a large scale chemical fertilizers, and commercial feeds that have short run benefits on both the farmers and land. In the long run, all stakeholders stand to lose to due to the distressing effects caused by agricultural and related industries. Prolonged use of chemical fertilizers, pesticides and herbicides lead to massive land pollution and reducing fertility of the same. Most of these chemicals are highly leeched and others are non-biodegradable and constant use of it causes accumulation in plant tissues.
Dumping of industrial waste also contributes to land pollution. In 2007 alone, Environment Protection Agency of the United Sates noted that there were more than 10 million pounds of harmful pollutants dumped. Major pollutants identified by this survey were heavy metals that comprise mainly of mercury, lead and arsenic compounds.

Water Pollution versus Industrialization
Ground water is mainly polluted through leaching processes. Surface water on the other hand gets polluted through a number of ways. One of the ways that rivers, lakes and seas, get polluted is when sulfur oxides combine with moisture to form acid rain then these flows into the water sources. Runoffs from polluted agricultural land, also leads to water pollution. Other ways that surface water gets polluted is through oil spills, water runoff from dumping sites and through deliberate disposal of industrial waste into water bodies.

Although modern man is justified to apply the current means of production and develop the current technology to use in industries and in food production to increase his food production, man is ignoring the fact that he plays a key role in the environment and he has the mandate to take care of the environment.
Human beings by his means through intensified means production due to rapidly growing population and the nature of demands dictates that man must engage in activities that expose the environment to a total risk of degradation.
In summary increased population or over population causes environmental degradation not by direct impact but through the activities that man undertake over the earth’s surface both in marine and terrestrial lands that includes; Intensive Agricultural activities, rapid growth of urban centers with unplanned settlements and  industrialization
Since mans action on the environment is justified due to the fact that man needs to derive source of livelihood, we are therefore left with no option as human beings and especially as environmentalists to device environmentally friendly ways that does not necessarily stop mans harm on the environment but means that reduce the effect and foster sustainable development.
Some of the ways might be; change in the means of Transport. This can be done by encouraging man to use public means that uses less fuel does less  emissions of Oxides into the Atmosphere. The use of commercial means of Transport saves both the non-renewable sources of Energy and also reduces the combustion of fossil fuels to produce petroleum products.
Secondly, we can adopt a culture of using renewable sources of Energy like solar energy and wind energy. Less has been done to harness wind energy which is eco-friendly type of energy.
Finally, we should encourage the use recycling of wastes and plan for companies in such a way that the waste products of one company becomes a raw material of another company.
According to the Population Policy for National Development(Kenya) Launched on 30th October 2012 proposes that average Kenyan women gives birth to  2.6 Children over the reproductive age of 15 to 49 years currently the woman gives birth to an average of 4.6 children. The policy further warns that the population will hit the 77Million mark by 2030 when the Kenya’s Economic blueprint, Vision 2030, expires-Daily Nation 31St October 2012.
Therefore, national family planning campaigns should be intensified so as to attain the 2.6. Children per woman between the ages of 15-45 years.
Awareness creation should be also intensified in rural and urban areas/informal settlements to curb the increasing population.

1.      Balmford. A et al, Measuring the changing state of nature TRENDS in Ecology and Evolution Vol.18 No.7 July 2003
2.      Central Statistical Organization, (2000), “Compendium of Environment Statistics,” Ministry of Statistics and Programme Implementation, Government of India, New Delhi.
3.      Cropper M., C. Griffiths (1999), “The Interaction of Population Growth and Environmental Quality” American Economic Review, 84:250-254
6.      The United Nations International Strategy for Disaaster Reduction (UNISDR) (2009) Terminology on Disaster Risk
7.      UNEP, 1999, “Unequal Impacts of Environment Damage, “Human Development Report 1999, Oxford University Press, New York.
8.      U.N HABITAT (1996), “An Urbanization World. Global report on Human Settlement. Instanbul.
9.      UNEP,Global Environmental outlook (1999/2000)

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