Population Growth And Its Effect On Environment Pdf
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- Population growth: Implications for environmental sustainability
- Impact of Population Growth
- Population and environment: a global challenge
The number of people on Earth, where they live, and how they live all affect the condition of the environment. People can alter the environment through their use of natural resources and the production of wastes. Changes in the environmental conditions, in turn, can affect human health and well-being.
Population growth: Implications for environmental sustainability
John P. Holdren , Paul R. It is more important now than ever to talk about population. What will we do if we continue to grow at exponential rates? What are ethical, viable strategies to decrease population? The interlocking crises in population, resources, and environment have been the focus of countless papers, dozens of prestigious symposia, and a growing avalanche of books. In this wealth of material, several questionable assertions have been appearing with increasing frequency.
Perhaps the most serious of these is the notion that the size and growth rate of the U. We propose to deal with this and several related misconceptions here, before persistent and unrebutted repetition entrenches them in the public mind—if not the scientific literature. Our discussion centers around five theorems which we believe are demonstrably true and which provide a framework for realistic analysis:.
In an agricultural or technological society, each human individual has a negative impact on his environment. He is responsible for some of the simplification and resulting destabilization of ecological systems which results from the practice of agriculture 3. He also participates in the utilization of renewable and nonrenewable resources. The total negative impact of such a society on the environment can be expressed, in the simplest terms, by the relation. A great deal of complexity is subsumed in this simple relation, however.
For example, F increases with per capita consumption if technology is held constant, but may decrease in some cases if more benign technologies are introduced in the provision of a constant level of consumption.
Pitfalls abound in the interpretation of manifest increases in the total impact I. For instance, it is easy to mistake changes in the composition of resource demand or environmental impact for absolute per capita increases, and thus to underestimate the role of the population multiplier.
Moreover, it is often assumed that population size and per capita impact are independent variables, when in fact they are not. Consider, for example, the recent article by Coale 1 , in which he disparages the role of U.
First, a closer examination of very rapid increases in many kinds of consumption shows that these changes reflect a shift among alternatives within a larger and much more slowly growing category. Thus the percent increase in electricity consumption from to 4 occurred in large part because the electrical component of the energy budget was and is increasing much faster than the budget itself. Electricity comprised 12 percent of the U. The total energy use, a more important figure than its electrical component in terms of resources and the environment, increased much less dramatically— percent from to Under the simplest assumption that is, that a given increase in population size accounts for an exactly proportional increase in consumption , this would mean that 38 percent of the increase in energy use during this period is explained by population growth the actual population increase from to was 53 percent.
Certainly, aluminum consumption has swelled by over percent since , but much of the increase has been due to the substitution of aluminum for steel in many applications. Thus a fairer measure is combined consumption of aluminum and steel, which has risen only percent since Again, under the simplest assumption, population growth accounts for 45 percent of the increase.
In short, he has failed to recognize that per capita consumption of energy and resources, and the associated per capita impact on the environment, are themselves functions of the population size. Our previous equation is more accurately written. Of course, whether F P is an increasing or decreasing function of P depends in part on whether diminishing returns or economies of scale are dominant in the activities of importance. In populous, industrial nations such as the United States, most economies of scale are already being exploited; we are on the diminishing returns part of most of the important curves,.
As one example of diminishing returns, consider the problem of providing nonrenewable resources such as minerals and fossil fuels to a growing population, even at fixed levels of per capita consumption, As the richest supplies of these resources and those nearest to centers of use are consumed, we are obliged to use lower-grade ores, drill deeper, and extend our supply networks.
All these activities increase our per capita use of energy and our per capita impact on the environment. In the case of partly renewable resources such as water which is effectively nonrenewable when groundwater supplies are mined at rates far exceeding natural recharge , per capita costs and environmental impact escalate dramatically when the human population demands more than is locally available.
Here the loss of free-flowing rivers and other economic, esthetic, and ecological costs of massive water-movement projects represent increased per capita diseconomies directly stimulated by population growth. Diminishing returns are also operative in increasing food production to meet the needs of growing populations.
Typically, attempts are made both to overproduce on land already farmed and to extend agriculture to marginal land. The former requires disproportionate energy use in obtaining and distributing water, fertilizer, and pesticides. The latter also increases per capita energy use, since the amount of energy invested per unit yield increases as less desirable land is cultivated. Similarly, as the richest fisheries stocks are depleted, the yield per unit effort drops, and more and more energy per capita is required to maintain the supply 5.
Once a stock is depleted it may not recover—it may be nonrenewable. Population size influences per capita impact in ways other than diminishing returns.
As one example, consider the oversimplified but instructive situation in which each person in the population has links with every other person—roads, telephone lines, and so forth. These links involve energy and materials in their construction and use. Since the number of links increases much more rapidly than the number of people 6 , so does the per capita consumption associated with the links.
Other factors may cause much steeper positive slopes in the per capita impact function, F P. One phenomenon is the threshold effect. Below a certain level of pollution trees will survive in smog.
But, at some point, when a small increment in population produces a small increment in smog, living trees become dead trees. Five hundred people may be able to live around a lake and dump their raw sewage into the lake, and the natural systems of the lake will be able to break down the sewage and keep the lake from undergoing rapid ecological change. Another phenomenon capable of causing near-discontinuities is the synergism. For instance, as cities push out into farmland, air pollution increasingly becomes a mixture of agricultural chemicals with power plant and automobile effluents.
Sulfur dioxide from the city paralyzes the cleaning mechanisms of the lungs, thus increasing the residence time of potential carcinogens in the agricultural chemicals.
The joint effect may be much more than the sum of the individual effects. Investigation of synergistic effects is one of the most neglected areas of environmental evaluation. Not only is there a connection between population size and per capita damage to the environment, but the cost of maintaining environmental quality at a given level escalates disproportionately as population size increases.
This effect occurs in part because costs increase very rapidly as one tries to reduce contaminants per unit volume of effluent to lower and lower levels diminishing returns again!
Consider municipal sewage, for example. The cost of removing 80 to 90 percent of the biochemical and chemical oxygen demand, 90 percent of the suspended solids, and 60 percent of the resistant organic material by means of secondary treatment is about 8 cents per gallons liters in a large plant 7.
But if the volume of sewage is such that its nutrient content creates a serious eutrophication problem as is the case in the United States today , or if supply considerations dictate the reuse of sewage water for industry, agriculture, or groundwater recharge, advanced treatment is necessary. The cost ranges from two to four times as much as for secondary treatment 17 cents per gallons for carbon absorption; 34 cents per gallons for disinfection to yield a potable supply.
This dramatic example of diminishing returns in pollution control could be repeated for stack gases, automobile exhausts, and so forth. This means per capita effectiveness of pollution control in this sector must double that is, effluent per person must be halved.
In a typical situation, this would yield doubled per capita costs, or quadrupled total costs and probably energy consumption in this sector for a doubling of population. Of course, diminishing returns and threshold effects may be still more serious: we may easily have an eightfold increase in control costs for a doubling of population. Such arguments leave little ground for the assumption, popularized by Barry Commoner 2, 8 and others, that a 1 percent rate of population growth spawns only 1 percent effects.
Such savings, if available at all, would apply in the case of our sewage example to a change in the amount of effluent to be handled at an installation of a given type. For most technologies, the United States is already more than populous enough to achieve such economies and is doing so. They are accounted for in our example by citing figures for the largest treatment plants of each type. Population growth, on the other hand, forces us into quantitative and qualitative changes in how we handle each unit volume of effluent—what fraction and what kinds of material we remove.
Here economies of scale do not apply at all, and diminishing returns are the rule. We will not deal in detail with the best example of the global nature and interconnections of population resource and environmental problems—namely, the problems involved in feeding a world in which 10 to 20 million people starve to death annually 9 , and in which the population is growing by some 70 million people per year.
The ecological problems created by high-yield agriculture are awesome 3, 10 and are bound to have a negative feedback on food production. Indeed, the Food and Agriculture Organization of the United Nations has reported that in the world suffered its first absolute decline in fisheries yield since It seems likely that part of this decline is attributable to pollution originating in terrestrial agriculture. A second source of the fisheries decline is, of course, overexploitation of fisheries by the developed countries.
This problem, in turn, is illustrative of the situation in regard to many other resources, where similarly rapacious and shortsighted behavior by the developed nations is compromising the aspirations of the bulk of humanity to a decent existence. It is now becoming more widely comprehended that the United States alone accounts for perhaps 30 percent of the nonrenewable resources consumed in the world each year for example, 37 percent of the energy, 25 percent of the steel, 28 percent of the tin, and 33 percent of the synthetic rubber Some observers argue that the poor countries are today economically dependent on our use of their resources, and indeed that economists in these countries complain that world demand for their raw materials is too low 1.
This proves only that their economists are as shortsighted as ours. It is abundantly clear that the entire context in which we view the world resource pool and the relationships between developed and underdeveloped countries must be changed, if we are to have any hope of achieving a stable and prosperous existence for all human beings.
Because of this consumption, and because of the enormous negative impact on the global environment accompanying it, the population growth in these countries must be regarded as the most serious in the world today. In relation to theorem 2 we must emphasize that, even if population growth were halted, the present population of the world could easily destroy civilization as we know it.
There is a wide choice of weapons—from unstable plant monocultures and agricultural hazes to DDT, mercury, and thermonuclear bombs. If population size were reduced and per capita consumption remained the same or increased , we would still quickly run out of vital, high-grade resources or generate conflicts over diminishing supplies. Racism, economic exploitation, and war will not be eliminated by population control of course, they are unlikely to be eliminated without it.
Theorem 3 deals with a problem related to the inequitable utilization of world resources. One of the commonest errors made by the uninitiated is to assume that population density people per square mile is the critical measure of overpopulation or underpopulation. For example, it is the second largest per capita importer of protein in the world, and it imports 63 percent of its cereals, including percent of its corn and rice.
It also imports all of its cotton, 77 percent of its wool, and all of its iron ore, antimony, bauxite, chromium, copper, gold, lead, magnesite, manganese, mercury, molybdenum, nickel, silver, tin, tungsten, vanadium, zinc, phosphate rock fertilizer , potash fertilizer , asbestos, and diamonds. It produces energy equivalent to some 20 million metric tons of coal and consumes the equivalent of over 47 million metric tons A certain preoccupation with density as a useful measure of overpopulation is apparent in the article by Coale 1.
His argument would be more persuasive if problems of population distribution were the only ones with environmental consequences, and if population distribution were unrelated to resource distribution and population size. Resources, such as water, are in very short supply, and people cluster where resources are available. Evidently, it cannot be emphasized enough that carrying capacity includes the availability of a wide variety of resources in addition to space itself, and that population pressure is measured relative to the carrying capacity.
One would expect water, soils, or the ability of the environment to absorb wastes to be the limiting resource in far more instances than land area. In addition, of course, many of the most serious environmental problems are essentially independent of the way in which population is distributed.
Similarly, the problems of resource depletion and ecosystem simplification by agriculture depend on how many people there are and their patterns of consumption, but not in any major way on how they are distributed.
Impact of Population Growth
AJOL and the millions of African and international researchers who rely on our free services are deeply grateful for your contribution. Your donation is guaranteed to directly contribute to Africans sharing their research output with a global readership. Skip to main content Skip to main navigation menu Skip to site footer. Abstract The impact of population growth on environment and its implication for survival is an important issue. Although considerable attention has been paid to this problem but systematic studies have been inadequate. Rapid population growth and economic development and daily demand for natural resources for domestic and industrial use are growing at an increasing rate, especially in an urban centre.
Urban environmental degradation is primarily associated with health impacts. As a result, the causes, consequences and distributional costs of.
Population and environment: a global challenge
John P. Holdren , Paul R. It is more important now than ever to talk about population. What will we do if we continue to grow at exponential rates?
Many people worry that population growth will eventually cause an environmental catastrophe. However, the problem is bigger and more complex than just counting bodies.
While the causes are complex, one significant contributor to the problem is population growth. Understanding the relationship between population growth and environmental issues may be the first step toward identifying real solutions. Population growth is the increase in the number of people living in a particular area. Since populations can grow exponentially, resource depletion can occur rapidly, leading to specific environmental concerns such as global warming, deforestation and decreasing biodiversity. Populations in developed countries trend toward using substantially more resources, while populations in developing countries feel the impacts of environmental problems more quickly.
The current population of the Earth is almost 7. While a lot of positive steps are being taken to better ensure the sustainability of humans on our planet, the problem of having too many people has made lasting solutions more challenging to find. The term overpopulation is used to describe a situation in which the world or area has a population so large that the people there are suffering as a result. In other words, the population exceeds the region or planet's carrying capacity--the number of people, other living organisms, or crops that can be supported without environmental degradation. Their suffering may include a shortage of food, limited access to healthcare and other public services, overcrowding, and high unemployment.
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Сьюзан была настолько ошеломлена, что отказывалась понимать слова коммандера. - О чем вы говорите. Стратмор вздохнул.
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Дэвид Беккер умрет. Халохот поднимался вверх с пистолетом в руке, прижимаясь вплотную к стене на тот случай, если Беккер попытается напасть на него сверху. Железные подсвечники, установленные на каждой площадке, стали бы хорошим оружием, если бы Беккер решил ими воспользоваться. Но если держать дистанцию, можно заметить его вовремя. У пистолета куда большая дальность действия, чем у полутораметрового подсвечника.
Вернувшись в лабораторию, Чатрукьян никак не мог решить, должен ли он идти домой.