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WORLD POPULATION AND FOOD PROBLEM David Pimentel Department of Entomology & Department of Ecology and Evolutionary Biology Marcia Pimentel Division of Nutritional Sciences CORNELL UNIVERSITY Ithaca, NY 14853-0901 The survival of the human population and the vital environmental resources that support it are being threatened by overpopulation. Entering the new millennium, stark contrasts are apparent between the availability of our natural resources and the billions of humans who require them for their survival (Pimentel and Pimentel, 2003). Each day about a quarter million people are added to the nearly 6.5 billion who already exist (PRB, 2003). Yet, the supply of natural resources that supports human life, including food, fresh water, quality soil, energy, and biodiversity is being polluted, degraded, and depleted. Considering the status of natural resources that support agriculture, it is evident that quality of human life, and survival are threatened. Many of these resources, especially those that are finite, like fossil fuel, are being depleted either by overuse or overexploitation. The on-going impact of population growth is being felt on all the life-supporting natural resources essential for agriculture and food production. WORLD POPULATION GROWTH The current world population of nearly 6.5 billion, doubled during the last 45 years. Based on its present growth rate of 1.3% each year, the world population is projected to double again within a mere 50 years (PRB, 2003). Many countries and world regions have populations that are rapidly expanding. For example, China's present population is 1.4 billion and, despite the governmental policy of permitting only one-child per couple, still growing at an annual rate of 0.6% (PRB, 2003). China, recognizing the its serious overpopulation problem, has recently passed legislation that strengthens its one-child per couple policy (China, 2002). However, because of its young age structure, the Chinese population will continue to increase for another 50 years. India, with nearly 1.1 billion people, living on approximately one-third the land of either of the United States or China, has a current population growth rate of 1.7%. This translates to a doubling time of 41 years (PRB, 2003). Taken together, the populations of China and India constitute more than one-third of the total world population. Given the steady decline in per capita resources, it is unlikely that India, China, or the total world population will double in the next 50 years. Also, despite the AIDS outbreak, the populations of most African countries also are expanding. For example, Chad and Ethiopia populations have high rates of increase and are projected to double in 21 and 23 years, respectively (PRB, 2003). The United States population also is growing rapidly and currently stands at nearly 300 million and doubled during the past 60 years. Based on its current growth rate of about 1.1% it is projected to double to 600 million in less than 70 years (USBC, 2003). Note, the U.S. population is growing at a per capita rate that is nearly twice that of China. A major obstacle in limiting human population growth is the very young age structure of the current world populations, as well as the population momentum that situation fosters. With ages that range from 15 to 40, reproductive rates are high (PRB, 2003). Even if all the people in the world adopted a policy of only 2 children per couple, it would take approximately 70 years before the world population would finally stabilize at approximately 12 billion, which is twice the current level (Population Action International, 1993). As the world and U.S. population continue to expand, all vital natural resources will have to be divided among increasing numbers of people and per capita availability will decline to low levels. When this occurs maintaining prosperity, a quality life, and personal freedom will be imperiled. MALNOURISHMENT IN THE WORLD The present world hunger and shortages of nutrients for many humans alerts us to the present serious problem concerning the world food supply and its impact on human health. The report of the Food and Agricultural Organization (FAO) of the United Nations confirms that food per capita has been declining since 1984, based on available cereal grains (FAO, 1961-2002). This is alarming news because cereal grains make up about 80% of the world’s food supply (Pimentel and Pimentel, 1996). Although grain yields per hectare in both developed and developing countries are still increasing, the rate of increase is slowing, while the world population and its food needs escalate (FAO, 1961- 2002; PRB, 2003). Specifically from 1950 to 1980, U.S. grain yields increased at about 3% per year, but since 1980 the annual rate of increase for corn and other major other grains is only about 1% (USDA, 1980 – 2003). According to the World Health Organization more than 3.7 billion people are malnourished (WHO, 2004). This is the largest number and proportion of malnourished people ever reported! The World Health Organization in assessing malnutrition includes deficiencies of calories, protein, iron, iodine, and vitamin A, B, C, and D shortages in its evaluation (Sommer and West, 1996; Tomashek et al., 2001). WORLD CROPLAND RESOURCES More than 99.7% of human food comes from the terrestrial environment while less than 0.3% comes from the oceans and other aquatic ecosystems (FAO, 2001). Worldwide, of the total 13 billion hectares of land area on earth the percentages in use are: cropland, 11%; pasture land, 27%; forest land, 32%; urban, 9%; and other 21 %. Most of the remaining land area (21%) is unsuitable for crops, pasture, and/or forests because the soil is too infertile or shallow to support plant growth, or the climate and region are too cold, dry, steep, stony, or wet (FAOSTAT, 2001). Per Capita Cropland In 1960, when the world population numbered only 3 billion, approximately 0.5 ha of cropland per capita was available. This area is considered essential for the production of a diverse, healthy, nutritious diet of plant and animal products -- similar to the typical diet of people living in the United States and Europe (Lal, 1989; Giampietro and Pimentel, 1994). Now as the human population continues to increase and expand its diverse activities, including transport systems and urbanization, vital cropland is being covered and lost from production. In the U.S., each person in the population requires 0.4 ha (1 acre) of land for urbanization and highways. China is an example of rapid change occurring in the availability of per capita cropland. There the amount of available cropland is only 0.08 ha per capita. This relatively small amount of cropland provides the Chinese people primarily a vegetarian diet. Chinese cropland is reported to be rapidly declining due to continued population growth, but also because of extreme soil erosion and land degradation (Leach, 1995). As a result of world population growth, the average available cropland per capita has diminished to less than 0.24 ha. This is about half the amount needed to provide diverse food supplies similar to those enjoyed in the U.S. and Europe. Now in the U.S. the average cropland per capita is down to 0.5 ha or the critical land area essential for food production (USBC, 2003). The availability of cropland influences the kinds and amounts of foods produced. For example, currently, a total of 1,481 kg/yr per capita of agricultural products is produced to feed each American, while the Chinese food supply averages only 785 kg/yr per capita (Pimentel and Pimentel, 2003). By all available measurements, the Chinese have reached or exceeded the limits of their agricultural system (Brown, 1997). Furthermore, the Chinese reliance on large inputs of fossil-fuel based fertilizers to compensate for shortages of arable land and severely eroded soils, combined with their limited fresh water supply, suggests severe problems looming in the near future (Pimentel and Wen, 2004). Even now China imports large amounts of grain from the United States and other nations, and is expected to increase imports of grains in the near future (Alexandratos, 1995). Loss of Cropland In addition to the intrusion of humans and their activities throughout the earth’s land area, degradation of soil has emerged as a critical agricultural problem (Pimentel and Kounang, 1999). Throughout the world current erosion rates are greater than ever before. Each year an estimated 10 million ha of cropland worldwide are abandoned due to soil erosion and diminished production caused by erosion (Faeth and Crosson 1994). Another 10 million ha/yr are critically damaged due to salinization, in large part as a result of irrigation and/or improper drainage methods (Thomas and Middleton, 1993). Further people in developing countries have been forced to burn crop residues for cooking and heating and this exposure of the soil to wind and rainfall energy intensifies soil erosion as much as 10 fold. Most of the additional cropland needed yearly to replace lost land comes from the world's forest areas (Houghton, 1994; WRI, 1996). The urgent need to increase crop production accounts for more than 60% of the massive deforestation now occurring worldwide (Myers, 1990). Topsoil renewal is extremely slow. In fact, it takes approximately 500 years for 2.5 cm (1 inch) of topsoil to reform under agricultural conditions (Troeh et al., 1999; Pimentel et al., 1995). Fertile topsoil is a precious agricultural resource. Soil erosion on cropland ranges from about 10 tons per hectare per year (t/ha/yr) in the United States to 40 t/ha/yr in China (USDA, 1994; Pimentel and Wen, 2004). During the past 30 years, the rate of soil loss throughout Africa has increased 20-fold (Vaje and Vagen, 2004). Under some arid conditions in India and with relatively strong winds, as much as 5,600 t/ha/yr of soil has been reported lost (Gupta and Raina, 1996). Related to wind erosion, on February 26th of 2000 the National Aeronautical and Space Administration photographed an enormous cloud of soil being blown from the African continent toward the South and North American continents (NASA, 2000). Granted some crops can be grown under artificial conditions using hydroponic techniques, but the costs in terms of energy expenditure and dollars is approximately 10-times that of conventional agriculture (Schwarz, 1995). Such systems are not affordable or sustainable for the future. WATER RESOURCES All life requires significant amounts of freshwater. The total amount of water made available by the world hydrologic cycle is sufficient to provide the current world population with adequate fresh water. Yet, world water supplies are concentrated in some areas, while other areas experience shortages or severely arid conditions. Water for Food Production All vegetation requires enormous quantities of water during the crop growing season. For example, an average U.S. corn crop that produces about 9,000 kg/ha of grain uses more than 6 million liters/ha of water during its growing season (Pimentel et al., 2004a). To supply this much water to the crop, approximately 1,000 mm of rainfall per hectare must reach the plants. If irrigation is required, about 10 million liters of irrigation water is required during the growing season (Pimentel et al., 2004a). Sources of Water Surface Water: Rainfall provides water found in streams, rivers, lakes, and oceans and it is a vital part of the hydrologic cycle (Gleick, 1993). Frequently surface water is not managed effectively, resulting in water shortages and pollution, both of which threaten humans and the aquatic biota that depend on it. The Colorado River, for example, is used so heavily by Colorado, California, Arizona, and other adjoining states, that by the time it reaches Mexico, it is usually no more than a trickle running into the Gulf of California. Ground Water: Rainfall is also stored in enormous underground aquifers. Their slow recharge rate from rainfall is usually only between 0.1% and 0.3% per year (UNEP, 1991; Covich, 1993). At such a slow recharge rate, groundwater resources must be carefully managed to prevent overuse and depletion, but this is not the case. For example, in Tamil Nadu, India, groundwater levels declined 25 to 30 meters during the 1970s because the pumping of irrigation water was excessive (UNEP, 2003). Similarly in Beijing, China, the groundwater level is falling at a rate of about 1 m/yr; while in Tianjin, China, it drops 4.4 m/yr (Postel, 1997). Similarly in the United States, ground water overdraft is high averaging 25% greater than replacement rates (Gleich, 2000). An extreme case is in California where some aquifers are being pumped 10 times faster than the recharge rate (Pimentel et al., 2004a). Rapid population growth and increased total water consumption combine to rapidly deplete water resources. The present and future availability of adequate supplies of freshwater for human and agricultural needs is already critical in many regions, especially in the Middle East and parts of North Africa where low rainfall is endemic (Gleick, 1993, 2000). Irrigation Irrigation enables crop production to succeed in arid regions, provided there is an adequate source of freshwater and fossil energy to pump and move the water. Currently, approximately 70% of the water removed from all sources worldwide is used solely for irrigation (Postel, 1997; White, 2001). Of this amount, about two-thirds is consumed by growing plant-life and is non-recoverable (Postel, 1997). An irrigated corn crop requires about 10 million liters per ha of water and uses about 3 times more energy to produce the same yield as rainfed corn (Pimentel et al., 1997; Pimentel et al., 2002). The limitation of surface and ground water resources for irrigation, and its high economic costs, plus the required large energy inputs, will tend to limit future agricultural irrigation. This will be especially true in developing nations where economics cannot support such expenditures. Water Pollution A major threat to maintaining ample fresh water resources is pollution. Although considerable water pollution has been documented in the United States (USBC, 2003), this problem is of greatest concern in countries where water regulations are not rigorously enforced or do not exist. This is common in developing countries that discharge approximately 95% of their untreated urban sewage directly into surface waters (WHO 1993). For instance, of India's 3,119 towns and cities, only 209 have partial sewage treatment facilities and a mere 8 possess full wastewater treatment facilities (WHO 1992). Downstream, the polluted water is used for drinking, bathing, and washing. ENERGY RESOURCES Humans have relied on various sources of power for centuries with solar providing most of the essential energy. Solar energy is vital to all natural ecosystems. The energy sources have ranged from human, animal, wind, tidal, and water energy, to wood, coal, gas, oil, and nuclear sources for fuel and power. Since about 1700, abundant fossil fuel energy supplies have made it possible to augment agricultural production to feed an increasing number of humans, as well as to improve the general quality of human life in many ways. Energy availability has made it possible to purify and to transport water. All these energy-based improvements have enhanced human quality of life. In essence ample energy supplies, especially fossil energy, have supported rapid population growth and increased agricultural production. In fact, the rate of energy use from all sources has been growing even faster than world population growth. Thus, from 1970 to 1995, energy use increased at a rate of 2.5% per year (doubling every 30 years) compared with the worldwide population growth of 1.7% per year (doubling about 40 years). During the next 20 years, energy use is projected to increase at a rate of 4.5% per year (doubling every 16 years) compared with a population growth rate of 1.3% per year (doubling every 54 years). Although about 50% of all the solar energy captured by worldwide photosynthesis is used by humans, this amount is still inadequate to meet all of human need for food and other purposes (Pimentel, 2001). To make up for this shortfall, about 350 quads (1 quad = 1 x 1015 BTU) of fossil energy, mainly oil, gas, and coal, are utilized worldwide each year for all activities (International Energy Annual, 2001). Of this, 93 quads are utilized in the United States (USBC, 2003). Each year, the U.S. population uses 4 times as much fossil energy as all the solar energy captured by harvested U.S. crops, forest products, and other vegetation each year (Pimentel, unpublished). Industry, transportation, home heating, and food production account for most of the fossil energy consumed in the United States (USBC, 2003). Per capita use of fossil energy in the United States is 8,000 liters of oil equivalents per year, more than 12-times the per capita use in China. In China, most fossil energy is used by industry, although a substantial amount, approximately 25%, now is used for agriculture and the food production system (Pimentel and Wen, 2004). Taken together developed nations annually consume about 70% of the fossil energy worldwide, while the developing nations, which have about 75% of the world population, use only 30% (International Energy Annual, 2001) The United States, with only 4% of the world's population, consumes about 24% of the world's fossil energy output. Some developing nations that have especially high rates of population growth are increasing fossil fuel use to augment their agricultural production of food and fiber. For example in China since 1955, there has been a 100-fold increase in fossil energy use in agriculture for fertilizers, pesticides, and irrigation (Pimentel and Wen, 2004). In general, world fertilizer per capita has declined by more than 17% since 1989, especially in the developing countries, because of fossil fuel shortages and high prices (Vital Signs, 2001). During the past year, the price of nitrogen fertilizer has increased 68%. In addition, the overall projections of the availability of fossil energy resources for fertilizers and all other purposes are discouraging as the stores of these finite fossil fuels decline. Fossil Fuel Supplies The world supply of oil is projected to last approximately 50 years at current production rates (BP, 2003; Ivanhoe, 1995; Campbell, 1997; Duncan, 1997; Youngquist, 1997). Worldwide, the natural gas supply is considered adequate for about 50 years and coal for about 100 years (BP, 2003; Bartlett and Ristinen, 1995; Youngquist, 1997). However, natural gas supplies are already in short supply in the United States and it is projected that the U.S. will deplete its natural gas resources in about 20 years (Youngquist and Duncan, 2003). Youngquist (1997) reports that current oil and gas exploration drilling data has not borne out some of the earlier optimistic estimates of the amount of these resources yet to be found in the United States. Both the production rate and proven reserves have continued to decline. Domestic oil and natural gas production have been declining for more than 30 years and are projected to continue to decline (USBC, 2003). Approximately 90% of U.S. oil resources already have been mined (W. Youngquist, personal communication, petroleum geologist, Eugene, Oregon, 2002; Pimentel et al. 2004b). At present the United States is importing about 62% of its oil (USBC, 2003). This dependency puts the U.S. economy at risk due to fluctuating oil prices and difficult political situations, such as the 1973 oil crisis, the 1991 Gulf War and the Iraqi War.