14 DECEMBER 2013 • WORLD AQUACULTURE • WWW.WAS.ORG Human Population Growth and Agriculture The human population was around 1 million when humans began to conduct agriculture about 10 to 12 thousand years ago. The ability to produce food by agriculture improved food availability and allowed human population to increase. Yet, the population grew slowly, reaching around 200 million by the beginning of the first millennium AD and about 750 million at the start of the Industrial Revolution in the mid-1700s. Since then, global population has increased rapidly: 1 billion by 1810; 2 billion by 1930; 3 billion by 1950; 4 billion by 1974; 6 billion by 1999 (Fig. 1). The world population at mid-year 2013 was slightly more than 7 billion and it is projected to increase to about 9.3 billion by 2050. The projected rate of population increase, however, is expected to decrease — especially after 2050. The exponential growth in population has required a tremendous increase in food production. Moreover, the population in many countries, especially China and India, has become more affluent during the last few decades — a trend that is expected to continue. Food consumption per capita tends to increase with better economic conditions; between now and mid-century, the demand for food will probably rise at a greater rate than will the rise in population. In the late 1790s, Thomas Malthus published an essay proclaiming that population increased exponentially while food production increased arithmetically. Malthus predicted that population in the future would be controlled by famine, disease, and wars. Such dire predictions have continued — the most famous modern day one was the 1968 book “Population Bomb” by Paul Ehrlich. Although there have been famines, epidemics, and wars since Malthus’ essay and Ehrlich’s more recent book, the human population has continued to grow. This phenomenon has been possible primarily through great advances in the ability of humans to control diseases and produce food. Agricultural Perspectives on the Responsible Aquaculture Movement Claude E. Boyd, Julio Queiroz, and Aaron McNevin production has increased about 3-fold since 1960 (Table 1). This huge increase in agricultural production has occurred despite an expansion in production area of a mere 10 percent. There would not have been enough arable land in the world to produce the amount of food needed by the current population had agricultural productivity remained at the 1961 level. The increase in agricultural productivity has resulted mainly from improved plant and animal crop species, mechanization, an increase in irrigation, and intensive use of fertilizers, pesticides, and other agrochemicals. As a consequence, advances in agriculture have led to many adverse environmental impacts through water, soil, and air pollution, introduction of exotic species, genetic modification of plants and animals and deforestation. Huge amounts of fossil fuel also are required for modern agriculture, resulting in emissions of carbon dioxide and other greenhouse gases. Scientific and technological advances associated with the Industrial Revolution led to a vast improvement in the human condition. Advances in medicine and sanitation lessened mortality from infections and common diseases that historically had imposed a bottleneck on population growth and the death rate fell precipitously. Greater industrial output and improvements in transportation, communications, housing, and other infrastructure necessary to support the burgeoning population became possible. Nevertheless, had it not been for advances in agricultural productivity, the human population could not have increased for lack of food. Famines in particular areas, world wars and other armed conflicts and disease epidemics have occurred since Malthus and Ehrlich published their works, but the human population has continued to increase. Nonetheless, nearly a billion people still suffer from undernourishment, and even more suffer from shortages of water, inadequate sanitation and medical care, poor living conditions, or some combination of these factors. The huge TABLE 1. Global agricultural production, 1961–2010. Year World Global Global Global Food population agricultural agricultural average yield available (billions) production (Mt) area (billions ha) (kg/ha) (kg/cap) 1961 3.09 2,567 4.46 576 831 1971 3.77 3,360 4.58 734 891 1981 4.51 4,070 4.67 865 902 1991 5.39 5,233 4.86 1,077 971 2001 6.20 6,219 4.97 1,251 1,003 2010 6.90 7,670 4.93 1,550 1,112 Source: faostat.fao.org.
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