Figure 1.2 introduces the root cause of environmental problems. As shown in the figure, Earth's population and the global use of fossil fuel energy are both growing at an alarming rate. The different scenarios referred to in the figure are based on slightly different assumptions in the population and energy consumption models used in the projections. On August 12, 1999, the world population reached 6 billion, and according to conservative estimates will reach around 9.8 billion by 2050 (with a variation of approximately 2 billion about this estimate). This increase has been the result of dramatic reductions in the death rates in all parts of the world; the birthrate is also presently on the decline in all parts of the world. The world population is expected to finally begin flattening out about the year 2100, assuming the developing nations reduce their rates of population growth as anticipated, in the future. Presently, however, the population is increasing exponentially at the rate of approximately 1.3% annually or by about 80 million people a year. That is about the total population of Germany or Mexico being added to the global citizenry each year! In one human life span (1930 to present) the population grew from 2 billion to the present 6.5 billion.6 The implications of this high rate of growth are underlined by the fact that most of this increase takes place within the developing regions of the world. Also, the life expectancy in all parts of the globe is slowly increasing, reaching an estimated average of
6 A world population of about 2 billion in 1927 doubled to 4 billion in the following 170 years. It is expected to double again to reach about 8 billion in 2028 (within a mere 54 years).
about 77 years by 2050. The global per capita energy consumption, however, has remained approximately the same in the recent past, and the demand for energy is at this time keeping pace with the increase in population. This projected population increase by 2050 should translate into at least a 75% increase in the future global demand for energy.
In 1798, Thomas Malthus  predicted a limit to growth in world population due to food production falling short of the demand by the rapidly growing humankind. The Malthusian prediction has not as yet materialized thanks to dramatically increased food production over the years. Green technology has until now prevailed and the food production has generally kept pace with the growth in world population. World grain production, for instance, has increased with the population growth, with the per capita production remaining around 300-344 kg from 1970 until the present time.7 Experts agree that today the world has more than enough food8 to feed the population, and hunger is merely a result of difficulties in distribution and allocation rather than unavailability of food. About a billion people suffering from hunger in today's world are mainly in Asia and Africa . (Interestingly, about the same number, but primarily in the West, suffers from obesity due to overconsumption.) Until about the year 2050 the demand for additional food will probably be met in most regions of the world (except perhaps in Africa, which will require a trebling of the food energy to sustain its population even at the medium variant of UN projections). Longer term supply of food relies to a great extent on future technological advances achieved in a timely manner, particularly on genetic engineering that would provide higher-yielding strains of cultivars that are also resistant to pests, better irrigation engineering, improved fertilizers, and more effective pesticides. Because of the impressive past performance, the Food and Agriculture Organization (FAO) is confident of no imminent scarcity of food supplies despite the rapid population growth. While the world has enough unused land capacity that might be put to agricultural use, the ability of the ecosystem to sustain intense food production in the future is not clear. In the past 25 years or so, the increase in food production was achieved not by increasing the area of total arable cropland but by more extensive use of fertilizers to increase crop yield. For instance, when the population doubled between 1960 and the year 2000, the supply of food comfortably kept pace with the increase, although the increase in farmland was only 12%. But the use of fertilizer jumped eight times to 80 million tons in the year 2000 ! Intensive agriculture is, of course, not without associated environmental damage. A common consequence of increasing fertilizer use in agriculture is the increased runoff entering large bodies of water, polluting them. Fertilizer-induced hypoxia
7 The soybean production on a per capita basis has nearly doubled over the same period to 23 kg. The per capita meat and fish production over the same period has either stayed the same or slightly increased (Worldwatch Institute).
8 It is adequate to provide the population with a nutritionally acceptable, but mainly vegetarian, diet. If the populace were given the free choice of the types of food they would like to consume, including some animal proteins, this may not be entirely true.
is already apparent in some regions of the northern Gulf of Mexico (cutting off oxygen particularly to the benthic organisms). Eutrophication due to excess phosphorous runoff from erosion of agricultural land threatens the health of freshwater ecosystems. A related concern is the environmental cost of manufacturing phosphate fertilizer itself; a by-product in the production of each ton of fertilizer is about 5 tons of phosphogypsum. Because of its trace radium content,9 this by-product is not used to any significant extent .
The burgeoning world population has to be supplied with goods and services as well as food, and the demand for goods has risen over a 100-fold since 1900. In the mid-1990s it took about 310 EJ (exajoules10) of energy, an alltime high, to support the global human activities. On average, each person on Earth consumes about the equivalent of a gallon of oil per day. A vast majority of Earth's population uses considerably less than this, while those in North America (and western Europe) typically use considerably more. The demand for energy has consistently increased year to year and is likely to continue to do so in the future, particularly in the developing economies. The fastest growth in fossil fuel consumption in recent years has been in North America.
Compounding the problem of uncontrolled population growth is the trend toward urbanization. Primarily because of the practical advantages of centralization of business and industry, cities have been a particularly successful phenomenon. Two clear trends are discernible; accelerated urbanization across the globe, and the increasing numbers of megacities with immense population densities. Better economic prospects and social opportunities attract large numbers to live under crowded, sometimes impoverished, conditions in megacities; there are presently about 20 cities with over 10 million inhabitants. While the most common type of human settlement still remains the rural village or town with less than about 10,000 inhabitants, over a half of the world's population by the year 2050 is expected to live in large cities. Cities such as New York and Mexico City already hold more people than the total population of small countries such as Sri Lanka, and those with populations of over 25 million will be common by the end of this century. (Good candidates include Sao Paulo, Tokyo, Mexico City, Calcutta, and Bombay.) Urban areas supporting a high population density must invariably suffer high levels of environmental damage and scarcity of natural resources as well. Any disproportionate expansion of a single species in the ecosystem must invariably be at the expense of others. Large-scale deforestation, loss in biodiversity, overfishing of the oceans, and increasing carbon dioxide loads released into the atmosphere are all indicators of this trade-off.
This book is more about polymers than environmental science. To achieve its goals fully, however, some minimal amount of environmental knowledge will
9 Phosphogypsum is chemically similar to natural gypsum but because of its radium content is unused and stockpiled. The production during the last 50 years is 700 Mt in Florida alone (USGS Fact Sheet FS 155-99 September 1999).
10 An exajoule is 1018 joules or one quadrillion Btus of energy. One exajoule is approximately equal to the energy derived from 163 million barrels of crude oil.
obviously be needed. To those as yet uninitiated, the summary discussion below will serve as a convenient starting point into the study of the environment. Several excellent sources are suggested for those interested in detailed information and a more complete discussion of the environmental arguments. This is followed by a collection of chapters on how plastics are related to specific environmental issues of interest. Those already familiar with environmental issues may wish to skip to these subsequent chapters.
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