Typology and Effects of Global Environmental Problems:
Recent years have witnessed a growing awareness of the need for better understanding of the effect of man’s activities on all facets of the global environment. This is reflected in an increased concern for the planning and exploitation of global resources, mounting fear for over the long term, large scale and synergistic effect of environmental pollution, interest in the long-term stability and productivity of the earth’s ecosystems and the global biosphere and generally heightened sensitivity to notions of environmental quality (Park; 1980; Ayuba, 2004). The areas of concern have crystallized in recent years due to mounting realization that the effect of man on his environment are now in many cases of a global scale, and there are few areas of natural environment where at least some forms of human impact are not apparent. Further impetus derives from recognition of the interdependence of many environmental problems because of the unity and complexity of the biosphere.
Many observers of environmental problems are
becoming increasing alarmed at the extent to which, and the speed with which human impacts in one part of the environment can trigger off serious if not irreversible changes in other parts of the environment. These secondary effects often occur in different places to the initial impact and they often become apparent only after a time lag. Prescription of cause and effect in environmental problems essential for wise environmental management and conservation thus becomes extremely difficult. Bennet and Chiorley (1978) advised that one approach to the diagnosis and solution of environmental problems lies in systems analysis, and it involves viewing the environment as a series of interconnected system, so that attention is focused on the external stimuli, internal functioning, and adjustment of the environmental systems.
Survey, which aim to assess the significance of human impact on ecological systems, have now attained high priority (NEST, 1992; Haine-Youg, 1991; Hitzhusen 1993, Ibrahim, 2003). Unfortunately, some of man’s physical landscape alterations are dramatic in impact whereas other effects are far more subtle (both in form and in scale), so that consequences are difficult to identify, let alone remedy. A complete examination of the different types of environmental problems is thus a stupendous taste. This research examines selected global environmental problems and their effects on the environment.
(1) DEFORESTATION
The removal of cover of natural woodland had often been regarded as the starting point for modern land deterioration (Mather, 1983). Deforestation is a complex environmental problem and its consequences manifest themselves in several forms such as erosion, flash floods, reduced stream flow, drought, fuelwood scarcity, sedimentation and microclimatic changes. Deforestation (BoWonder, 1983) is caused by indiscriminate felling of trees for fuel wood, clear felling of forests for plantations, shifting cultivation, intensive grazing in forests, large-scale extraction of wood for paper and pulp manufacturing, conversion of forest for agriculture and poor effects for forest-regeneration in term of input and investments.
The developing countries together deforest 11.3 million hectares per year (Guppy, 1984). In countries like India, Haiti, Indonesia, Malaysia, Tanzania and Brazil, the deforestation problem is severe. Over 250,000 hectares are converted to non-forest land use each year (Wood, 1991). The major reason for forest degradation is the fuel wood collection by the poorer section of the population. Fuel wood use exceeds 1.6m3 per capital per year in Kenya, Sudan, Tanzania, South Korea, Liberia, Cameroun and Sierra Leone, (BroWonder, 1986). In many developing countries, fuel wood use per capital is on the increase. Fuel wood extraction in a number of countries such as Burundi, Ethiopia, Guinea, Kenya, Rwanda, Uganda, Ghana, Pakistan, Nigeria and Egypt is more than the sustainable yield (Bowonder, 1983; NEST 1998). Both economic and biological over-extraction of tropical forests will continue because of the common property status and high price of forest resources induced by the fuel wood shortage. In the case of common property resources, institutional mechanisms for stimulating the capital stock are rather weak.
Some of the consequences of deforestation are extinction of species, loss of fixed carbon, and reduced capability of the soil to store water, which makes the farming systems sensitive to droughts. Deforestation causes a number of physical changes and reversing all of them is not possible. Some of the changes that follow deforestation are stream flow increases, transpiration is reduced, concentration of dissolved organics in water is increased, erosion increases, soil temperature increases, rate of decomposition increases, rate of nitrification increases, canopy absorption is reduced, and dissolved substance in the soil increase. Tropical deforestation can have severe consequences to the farming capability which is the base for development in highly populated developing countries. The main reason for this is that in Africa and Asia, majority of the areas have leached and weathered soil with low nutrients and clearing reduces the productivity drastically. It will not be easy to reverse the trends of deforestation in the short run, since the problem is linked to the satisfaction of a basic need.
While the temperature zone forests are afflicted by industrial air pollution, particularly from acid rain, the tropical forests are decreasing because of deforestation is not compensated by reforestation. In Europe and North America, widespread damage of the forests has been reported (Purdis, 1983). In Canada, green forests are turning gray. South of Quebec City, the maple forest that makes the area the world’s maple Syrup capitals are dying in huge numbers. Damaged trees are in an area that is severely affected by acid rain from Ontario, Quebec and U.S Industries. Thus, the impact of civilized man on forests in recent centuries has had drastic short-term effects and is likely to have far reaching effects on the biosphere. Those forest ecosystems are both stable and vulnerable; their survival through geological time shows that they possess a great capacity to withstand the climatic and other hazards of the natural environment but when faced with man and modern technology, they prove very fragile.
It is suggested (Skoupy, 1991) that forest ecosystem programmes should focus attention on:
(i) Assessment and monitoring of forest cover and quality of ecosystems at global and regional scale and in selected cases at lower level;
(ii) Monitoring climatic, hydrological or pedological and ecological conditions of plants,
(iii) Formulation and promotion of program of activities for sustainable management of tropical forests, development of environmentally sound farming and forestry practices including agroforestry.
(iv) Promotion and support of research in the fields of integrated management of forest resources, biological diversity and process and forest genetic resources;
(v) Improving and controlling the use of fuel wood and charcoal, and pursuing alternative sources of energy and
(vi) Maintaining and protecting existing vegetation, and revegetating damage areas.
Unless long-term perspectives are introduced in the policy-making framework, the existing resource utilization patterns and trends of forest depletion will continue.
(2) SOIL EROSION
Soil erosion is the removal of soil by wind, water and mass movements at a faster rate than at which new soil forms. It involves the detachment and transportation of soil particles from one location and eventual deposition at another point. In soil erosion and conservation texts (Hudson, 1971; Faniran and Areola, 1978, FAO Soil Bulletins), fundamental distinction is made between erosion at natural rates and that at accelerated rates. It is generally implicit that for natural rates of erosion, a balance exists between the rates of soil loss and soil formation, and that man is the chief cause of upsetting this balance. On a global scale, soil erosion is associated with misuse of the land where the soil is inadequate protected by plant cover. It occurs with arable cropping, overgrazing, mining and intensive recreational use.
The most serious form of soil degradation is thus from accelerated soil erosion. The rate of soil erosion caused by water and wind exceeds by far its renewal rate (about 0.5cm in 100 years, Doos, 1994); in temperature regions by about 10-20 times and in the tropics by twice as much (Swaminathan, 1991). The total global reservoir of soil has been estimated to be about 3.5 x 1012 metric tons and the rate of erosion above replacement to be about 23 x 109 metric ton per year (Brown 1984, 1988). The annual loss of soil is thus about 0.7%, which implies that by 2025, the loss of soil will be somewhat more than 20% of the total reservoir. In Africa, 11.6% of the total area is affected by water erosion that 22.4% by wind erosion, in the Near East 17.1% of the total area is affected by water erosion, 35.5% by wind erosion (FAO Soil Bulletin, 1983) Erosion removes the top soil, the zone of plant nutrients and thus causes steady reduction of soil fertility. Food crop are the worst hit by this development due to their shallow rooting systems. The decline in agricultural production resulting in food shortages, high food prices and famine, adversely affect the nutrition and health of the population and cause decline in productivity.
There is drastic reduction in land productivity for agriculture. In the case of Gully erosion, the land may become sub-maginal and no longer useful of any purpose. Much of the eroded soils are deposited in water system leading to pollution and siltation by sand and particulate. The result is drastic reduction water volume and quality, and eventually siltation and drying of rivers, water reservoirs and dams. The aquatic life is eventually eliminated. Pollution and siltation of water system, including flooding have adverse consequences for economic life of local communities, and could result in the displacement of communities downstream. Water supply for domestic and industrial purposes would become scarce and more expensive. Soil erosion causes the terrain to be grossly uneven and where soil parent material is exposed, it is necessary to undertake filling before civil construction and other infrastructural works such as building bridges and roads can be carried out. The site reclamation which this situation demands is very expensive and may increase the overall cost by up to 30%. Moreover, additional costs must be incurred to protect such susceptible site against further erosion.
The need for prevention and control of erosion through timely and appropriate management techniques and other measures cannot be overemphasized. The basic aim of management of erosion should be to stabilize the soil for maintenance of high productivity and raising living standards of the dependent communities. For effective management of soil erosion, emphasis should be in prevention of deterrent measures among which the establishment of appropriate tree/vegetation cover in exposed soil and adaptation of suitable land use practices are most important. Measures for early detection of onset of soil erosion and immediate application of solution to retard its expansion are mandatory.
(3) DESERTIFICATION
According to the United Nation Programme-World Conference in Desertification, desertification is the diminution or destruction of the biological potential of land leading ultimately to desert-like conditions. Desertification is a self-accelerating process, feeding on itself, and as it advances, rehabilitation cost rise exponentially (UNCOD, 1977). Kassas (1988) define desertification as primarily a man-made ecological degradation by which, bio-productivity potential (in economic terms) of land is reduced. This is often a gradual process that operates through systems of land use that overtax inherent bio-productive capacity.
There is now a strong global mood for re-assessment of earlier definitions and earlier basic assumptions about the process of desertification. Opinion on swinging in the direction of seeing desertification as a slow and insidious process of land degradation, which is on the one hand exacerbated by prolonged drought, and on the other, by carelessness in resources use by human population. In that respect, the following is offered as possible compromise definition, which should satisfy the scientific as well as the development communities, desertification is the process of land degradation characteristics of the arid, semi-arid and sub-humid area of the world. The process, which is largely human-induced, is normally exacerbated by adverse climatic conditions such as prolonged drought or desiccation, which enable it to strike at the land resource base by weakening the physical, biological and economical potential of the land, thereby severely reducing or curtailing overall productivity (Odiongo, 1990). The areas most affected by desertification are mainly on the fringes of the great deserts (The Sahara, Kalahari, Atacama, Australian, Chinese and the Arabians); that is, in arid lands (200-250 mm annual rain) and semi-arid lands (250-800 mm) representing more than 30 million square kilometers (20%) of the earth’s surface.
Desertification is a highly interactive problem. Desert ecosystems are inherently vulnerable to stress, have light texture of soil, and low water retention. Such systems when subjected to high rates of biomass extraction, and the digging of shrubs and roots for fuel, degrade very rapidly, further impairing the productivity. Desertification brings about a catastrophic change since biomass yield or vegetation density and relative erosion exhibit sudden and irreversible transition (BoWonder, 1984). This aspect makes it necessary to have systematic monitoring of area prone to desertification in term of soil conditions, biomass productivity, soil moisture retention and land use changes. Recovering biomass in desert ecosystem is slow, expensive and difficult (Armitage, 1985).
The phenomenon of desertification is a serious malady that periodically afflicts Nigeria. Oladapo (1993) observed that 15% of the country is prone to severe desertification. Sand dunes have been reported to have leveled up vast area of farmland and swept whole communities in the Northern fringes of Nigeria (Ibrahim, 2003).
The key to mitigation the impacts of desertification (and drought) is the formulation of a comprehensive, coherent, systematic, well coordinated and sustainable development strategy, which takes cognizance of the vagaries of the climate, the fragile nature of the ecosystems and needs aspirations, perception, indigenous knowledge and traditional resource management practice of the people in the region. A well-integrated drought and desertification strategy should include (Oladipo, 1994)
(i) A shift in emphasis from post-disaster and adhoc relief measures to pre-disaster preparedness.
(ii) The establishment of early warning systems.
(iii) Flexible agricultural plan.
(iv) The integration of disaster planning into the mainstream of government decision-making.
(v) Increase transfer of appropriate and replicable technology and knowledge to those at risk.
Such a strategy must have built into it a mix of short-term and long-term measures and must be designed to involve the local people through its planning stages to it implementation. The calls for a better coordination of the links between different levels of government.
(4) OVERGRAZING
In the past three decades, there is widespread recognition that livestock population are an important factor in the ecological degradation prevailing in many of the arid and semi-arid grazing lands of the world. Grazing lands cover about one-third of the world’s land surface. They include many areas in arid and semi-arid regions, as well as mountainous and high altitude zones, which are two steep or too hot, too cold or too dry for intensive cultivation. These lands have low productivity per unit area, and are inherently fragile. Over exploitation triggers soil erosion, desertification and other process of degradation. Productivity is quickly diminished, with far-reaching consequences on the local and national economy and on the well being of the people concerned.
Many of the tropical and subtropical grazing land have declined in fertility as a result of overgrazing. Botanical composition has changed as a result of continued selective grazing, which has removed the more palatable and nutritious species (Skerma and Riveros, 1990; Skarpe, 1991, Ayuba 1998, Ayuba et al, 2004). Overgrazing has succinctly been described by Weaver and Clements (1938) as follows: The more palatable species are often down, thus rendering the uneaten one more conspicuous. This quickly throws the advantage in competition to the site of the lattes. Because of more water and light, their growth is greatly increased. They are enabled to store more food in the propagative organs as well as to produce more seed. The grazed species are correspondingly handicapped in all these respects by the increase of the less palatable species and the grasses are further weakened by trampling as stock wanders about in search of food. Soon bare spots appear that are colonized by weeds or weed-like species.
The term overgrazing refers to the harm caused by animals to both rangeland and individual plants, as well as to the soil. Erosion may result and dust may settle on the vegetation, reducing photosynthesis. In Mediterranean grasslands grazed by domestic livestock, Noy-Meir et al (1989) observed that tall perennial and tall annual grasses dominated ungrazed sites, whereas small prostrate annual were abundant in heavily grazed sites. Whereas perennial species were somewhat more frequent among protected sites grazing response was strongly associated with plant growth form, even though individual species were not always consistent across sites in their response to grazing. Such inconsistency among individual species between local sites in response to grazing has also been observed for small mammal grazing and for wet versus dry years within the small site (Crawly, 1990; Milchunas et al, 1989).
Experience in South-Africa has shown that when continuous grazing was combined with heavy stocking rate, sward degeneration followed because of the overuse of preferred areas, species or individual plant. Ayuba (1998) observed that is a significant transfer of nutrient from distant grazing areas to the environs of watering points and the livestock resting areas, thus, leading to undesirable weeds being established in such fertile area. Mc Naughton (1979) reviewed the literature on potentially positive effect of grazing upon the productivity of grazed vegetation and summarized his conclusion in nine points. Productivity of herbivore affected plants tissues may be compensated or stimulated by increased phythetic rate in residual tissue, mechanical removal by order tissues functioning at less than a maximum photosynthetic level, reallocation of substrates from elsewhere in the plant, consequent increased light intensities upon potentially more active underlying tissue, reduction of the rate of leaf senscence, this prolonged the active photosynthesis period of residual tissues, hormonal redistributions promoting cell division and elongation and activation of renaming meristems, this resulting in more rapid leaf regrowth and promoting of tillering, enhanced conservation of soil moisture by reduction of the transportation surface and reduction of mesophyll resistance relative to stomata resistance, nutrient recycling from dung and urine, and direct effect from growth promoting substrates in ruminant saliva.
On the other hand, grazing can have large negative impacts on some arid and semi-arid regions through its effect on erosion. The loss of soil fertility by erosion can lead to desertification of formerly protected lands. The existing patterns of most of the world’s rangelands are unsatisfactory and contribute to growing human suffering as well as destruction of natural resources. Yet in most of these rangelands a relatively small expenditure of development money, wisely applied can go far towards restoring healthy and productive vegetation of the support of an abundant animal life and for the enrichment of man. Essential to this process however, is the ability to recognize the existing status are tread of rangelands in relation to the potential for the site. Indentify the factors causing damage, and suggest a management program, with the support of the local people to eliminate factors that accelerate rangeland degradation and develop the highest potential of the area. Sustainability of the rangelands depends among other things on knowledge of actual conditions of the particular sites knowledge of the factors that have resulted in the vegetation reaching its present condition and knowledge of the direction and rate of change under existing condition of management. Insufficient attention to these requirements has been an underlying cause of failure in many development projects.
(5) INDISCRIMINATE BUSH BURNING
Fire is acknowledged as a factor of the Savanna environment where summer rain promotes the growth of tall grasses, which readily ignites as the onset of the dry season. It is recognized that fire has fundamentally altered the original vegetation of the Savanna ecosystem. The influence of fire on the farm and composition of the vegetation and soil has been highlighted by several authors (Trapnel et al, 1976; Odigie et al 1983; Udo, 1990; Akinyemi, 1990; Ayuba, 1994). The effects of this indiscriminate burning can cause a loss of most of nitrogen, sulphur and carbon; elimination of seedlings of fire tender, tree species to survive, destruction of humus and adverse soil physical and textural characteristics particularly where intense burning is achieved, adverse effects on soil macro fauna and destruction of soil micro flora.
Baba Ali Mustapha is with the Department of Planning/Research, Ministry of Environment, Maiduguri, Borno State, Nigeria
Reference:
The research work was based on the work of Professor Haruna K. Ayuba and Dr. A. Dami, both of University of Maiduguri, from their Book “Environmental Science, an introductory Text”.
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