Environmental Issues

"Over"-Population and Future Un-Sustainability
"Human population growth is the primary environmental challenge we face.." (Cousteau, 1993). Is this a statement valid? The human population has grown at alarming rates in the past century due to vast improvements in average quality of life, and with such a large base it is inevitable that it will continue to grow, even if the rate of growth slows. Increasing population leads to scarcity and contamination and arguably, a decline in average quality of life. However, is overpopulation the real issue? There are many negative effects of population growth, mainly depletion and degradation of resources. According to Thomas Malthus, one of the most famous population theorists, population growth would only lead to natural population controls such as famine and disease. Malthus believed that the main factor controlling population growth was food supply. Despite the validity of Malthus’ worries about the population growing faster than its food supply, there are several other details that need to be taken into account. Many different resources contribute to the sustainability of the population, all of them interrelated. This essay will examine some of these resource restraints on population growth as well as attempt to show that it is not only the size of the population that is the problem. If there were a more equal distribution of resources, instead of great disparities between rich and poor, then the size of the human population would pose less of a challenge than it now does. Regardless of equitable distribution there is however, a limit to which the population could grow and continue to provide for all of its people.

Although Thomas Malthus was not the first to raise the issue of the "population problem", his 1798 essay "An Essay on the Principle of Population" is perhaps the most famous work of its kind. This is not to say that many people agree with him, because there is much debate concerning his theory. Malthus ultimately stated that "the power of the population is indefinitely greater than the power in the earth to produce subsistence for man" (Morris, 1966). He expanded on this by writing that although population grows exponentially, food supplies increase only arithmetically so a growing population will not be able to be sustained by its slower growing food supply. According to Malthus this would lead to "population checks" such as famine and war which were natures ways of controlling overpopulation. Along with these positive population checks Malthus also claimed there were preventative checks such as the deterrent of early marriage (and therefore early and more frequent childbirth) during difficult times. All of these checks were related to limited food supply, Malthusianisms ultimate barrier against population growth. Famine and malnutrition led to increased disease, which would lead to lowered employment which in turn could encourage or discourage marriage. In this sense each of the population checks were mutually reinforcing, although all stemmed from lack of food (Morris, 1966).

Thomas Malthus’ theory is not entirely valid in that he did not acknowledge the limited supply of other essential resources that would arise from the increasing human population. Since he published his essay before the industrial revolution Malthus could not have been expected to predict the massive effects that a larger population would have on the environment and the large scale depletion of necessary resources that would occur. Food supplies are not necessarily the limiting factor on population (and cause of population checks), but instead a combination of the lack of, and unequal distribution of, clean water, air and energy sources that could lead to a worldwide crisis. In a sense, Malthus only discussed one factor of overpopulation and did not account for the future over consumption that is perhaps the real problem.

Over consumption, by the rich minority, may actually a more important issue than that of overpopulation. Over use of critical resources, and degradation of the remaining supplies, has led to these resources being unsustainable at current levels of use. First examining the state of nonrenewable energy sources (principally coal, petroleum and natural gas) it is clear that unless major changes in consumption are made there will be a need for alternate energy sources in the very near future. According to John Harte (1993) even if total consumption levels remained at 1990 levels (a highly unrealistic scenario looking at past trends), new energy sources are necessary to maintain sustainability. A slightly more realistic scenario would be if future per-capita energy consumption remained at 1990 levels with population growth of two percent per year. In this case the three principle nonrenewable energy sources would last only between twenty-nine to eighty-four years (Harte, 1993). Not only are fossil fuel energy sources being depleted, but a growing population also decreases firewood supplies, the primary fuel for a third of humans (Brown et al, 1976). In developing countries, this is often the only affordable source of energy and as the number of people grows there is less space, water and arable soil as well as a greater demand for wood for other needs. All of these factors contribute to deforestation which means less wood fuel available as an energy source.

It is important to examine not only the sustainability of current reserves but also the environmental effects that use of these resources will have. It is however impossible to know all of the environmental effects of anything, since each action has so many reinforcing and far-reaching consequences. In the case of energy sources, fossil fuels, as well as the wood fuel which is often the only affordable option for the poor, cause air pollution which contributes to climate change. This may affect other resources, such as water supply and arable land as a changing climate alters growing seasons and water levels. Deforestation occurs as more and more wood is needed, and as the space taken up by the forests is needed to house growing population and industry. This compounds the problem of global warming since there are less trees to absorb and store carbon dioxide (one greenhouse gas) and transform it into oxygen. Fossil fuel use also contributes to acid deposition which likewise affects water and soil supplies as they acidify and can no longer support life.

Another essential resource that will be, and already has been, greatly affected by a growing population is water. Unlike energy resources water has no substitute. Falkenmark (1986) estimated that the absolute minimum per capita supply required for drinking, sanitiation and other basic personal needs in a moderately developed nation was approximately one thousand meters cubed per year. The average per capita supply will fall below this level when the population is 9.5 times its 1993 size (Harte, 1993). According to Shiklomanov (1993) the global average rate of water withdrawal for human use was 800 metres cubed, while the United States average rate was 2000 metres cubed per year. This is just one example of massive disparities that exist between "developed" countries (especially the United States), and the remainder of the world.
However, water is necessary not only for personal use but also for agriculture and industry (not to mention to support all other life as well). This means that even when the water is not consumed it is still not necessarily available for reuse if it has been contaminated by pesticides, heavy metals and many other pollutants. Although it is possible for humans to improve this degradation the processes are expensive and are often not used. Also water is often not in a closed system so pollution in one area can spread universally through the hydrologic cycle. As discussed above, global warming from human pollutants could contribute to increased water loss from earth to the atmosphere. This is also positively reinforcing since warm air can hold more water and water droplets are one greenhouse gas which in turn cause more warming (Harte, 1993). This is just one effect that depleted water supplies could have. Water loss from soil would decrease crop production and warming lakes and oceans could possibly increase exhaustion of fish stocks.

As developing countries industrialize there will be an even greater conflict between water uses for personal consumption and sanitation and for agriculture versus growing industrial needs. This industrial use will also contribute to and complicate severe biological water pollution problems already existing in these countries that often have few environmental or water sanitation programs in place. Human organic waste has accumulated in the surface water supplies as population increased. This can lead to water-based diseases such as schistosomiasis, a parasitic illness carried by snails that live in irrigation water polluted with human waste. It permanently damages the bladder and liver, leading to a shortened lives, and it is at an epidemic level in many developing countries (Brown et al, 1976).

The third essential resource for a sustainable human population is soil and its use for food production. Approximately 15 million square kilometers were being used for cultivation in 1993 and it is estimated that only about 10 million square kilometers more could be tilled without causing irreversible ecosystem damage. Assuming that crop yields remain constant on this additional land and that the population grows at two percent per year, then only enough food can be produced to feed the human population for approximately twenty-five years (Harte, 1993). However these estimates do not account for soil degradation or erosion. These can be caused by over harvesting the soil which removes essential nutrients, or from decreasing vegetation which would prevent erosion. Pressure from population growth often causes humans to act in ways that increase soil erosion. More people need more wood which leads to deforestation, and more cattle to feed the people causes overgrazing. In this way, as the population grows and requires more food, it is also decreasing the capacity of the soil to provide food so population growth has greater-than-linear effects on its environment (Harte, 1993). Soil erosion, like any environmental problem, also has effects on many other systems than simply crop yield. Eroded soil clogs waterways, reducing the lifetime of reservoirs and increasing the likelihood of floods. Nutrients washed from the soil into surface water can cause eutrophication of these streams and lakes (Harte, 1993). These are merely more examples of the complicated and far reaching effects of any human interaction with the environment.

It is obvious from the above that there is a limit to which current water, energy and soil resources can provide for a growing population. As well as the direct effects that the dwindling of these resources will have the quality and quantity of each of these also plays a role in the amount of food supply available in the future. The three main food systems are; fish from the oceans, animal herds on range lands and farmland used for crops. Each of these systems faces degradation from a multitude of uses, and this is further depleting the ability of each system to provide food for the growing population. As well as the effects of pollution and global warming which may decrease oceanic fish stocks, there is also the direct result of heavy over fishing which caused a crash in most fish stocks in the eighties, resulting in much reduced or non-existent harvests in the early nineties (Brown et al., 1994, p.76). According to the United Nations Food and Agriculture Organization (1991) all seventeen major oceanic fisheries are being fished at or beyond their capacity. The potential of the oceans to feed humans is not only not growing at the same pace as the population, but is declining.

In the same sense, over grazing of range land and over harvesting of crop land contributes to soil erosion and degradation diminishing the capacity of the soil to support these activities. This catch 22 means that, assuming human methods remain the same as past trends, as population grows the land will become more and more over worked decreasing its future sustainability to support further exploitation. Many economies in the South, mainly in Africa and Middle East and Central Asia, depend on livestock to sustain and employ the population. Range lands are, like fisheries, already being grazed at or beyond their limit. This is also true of crop lands, which as they are over harvested, lose essential nutrients through increased erosion, thus decreasing their future capacity to provide crops (Brown et al, 1994).

Thomas Malthus stated that the ultimate limiting factor on human population growth would be limited food supplies. It is possible that this is true although it is a simplification of the real issue. In actuality the three main threats that are threatening humanity are; the rapid increase in world population, the limits to nonrenewable resources and the deterioration of the environment, all of which are inextricably linked and reinforcing (Sauvy, 1975). Another complicating component is the issue of inequitable distribution of the resources that are available. Some theorists insist that adequate food exists to provide for all the worlds people, it is just not distributed properly. Whether this is true or not, it obviously will not remain true with the ongoing rapid population growth and the lack of a corresponding growth in food supplies (Wirick, 1985).

With the current population being as large as it is even if the rate of growth decreases worldwide, as it has in many countries in the South, overall growth will mean large absolute additions. This growth has been a result of improved quality of life leading to decreased infant mortality and increasing life expectancies. Despite these improvements, there has still been a rise in the number of those living in absolute poverty. These improvements have come at the expense of the environment. Advances in "developed" countries have come at the expense of "developing" nations. Countries in the North exploit the lack of environmental laws in the South to attain development without harming their own local environment. Meanwhile citizens of these "poor" countries must also exploit their own resources if they are to merely subsist, let alone "develop" (Ness et al, 1997). This is a huge disparity that must be addressed before any real, global, sustainable development can occur.

Some compromise must be found that promotes the good of both people and the environment. In order to do this new ways of thinking, planning and acting will have to be found that focus on human sustainable use of natural resources instead of simply environmental conservation and emphasize human welfare and responsible parenthood instead of population control (Ness et al., 1997).

Sarah Brimson, 2001

References

Brown, Lester R., McGrath, Patricia L., and Stokes, Bruce. March 1976. Worldwatch Paper 5: Twenty-two dimensions of the population problem. Worldwatch Institute. Pages 25 & 75.

Brown, Lester R. and Kane, Hal. 1994. Full House: Reassessing the Earth’s Population Carrying Capacity. Starke, Linda (ed.) The Worldwatch Environmental Alert Series. USA: Worldwatch Institute.

Cousteau, Jean-Michel. 1993. Population: Challenge to Biosphere and Behavior. Zuckerman, Ben and Jefferson, David (ed.), Human Population and the Environmental Crisis. California: Jones and Bartlett Publishers, Inc.

Harte, John. 1993. On the sustainability of resource use: population as a dynamic factor. Zuckerman, Ben and Jefferson, David (ed.), Human Population and the Environmental Crisis 1996. California: Jones and Bartlett Publishers, Inc.

Falkenmark, G. 1986. Fresh water-time for a modified approach. Ambio 15(4):192-200.

Morris, Judy K.1966. Professor Malthus and His Essay. Population Bulletin 22 (1). Washington, DC: Population Reference Bureau, Inc. pp7-27

Ness, Gayl D. with Golay, Meghan V. 1997. Population and Strategies for National Sustainable Development: A Guide to Assist National Policy Makers in Linking Population and the Environment in Strategies for Sustainable Development. UK: International Union for Conservation of Nature and Natural Resources.

Sauvy, Alfred. 1975. Zero Growth? New York: Praeger Publishers, Inc.

Shiklomanov, I.A., 1993. World fresh water resources. In:P Gleick (ed.), Water in Crisis: A Guide to the World’s Freshwater Resources. (Oxford, UK: Oxford University Press), pp.13-24

U.N. Food and Agriculture Organization (FAO). 1991. Yearbook of Fishery Statistics: Catches and Landings. Rome.

Wirick, Gregory. 1985. North-South Institute Briefing, World Population: Continuing Challenges. The North-South Institute.