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.

TOP, FIGURE 1. World population growth from 1750 to present with projections to 2100. BOTTOM, FIGURE 2. Total world fisheries and aquaculture production since 1960.

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 production has increased 3-fold since 1960. 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 hugepopulation also is rapidly depleting many non-renewable resources and degrading the world’s ecosystems. Many feel that the dire predictions of Malthus, Ehrlich and others have been merely delayed

Environmental non-governmental organizations (eNGOs) have been and continue to be extremely concerned about the sustainability of the world’s ecosystems and its human population. The general consensus of the eNGOs is that the world’s ecological footprint has exceeded its available biocapacity by a factor of 1.3 or more. These organizations are exerting pressure on consumers, industries, and governments to conserve resources and to improve environmental stewardship. Aquaculture is an old endeavor dating back thousands of years, but it came of age in the midst of the current era of environmental awakening and is embroiled in the sustainability controversy.

Stagnation of Capture Fisheries and the Rise of Industrial Aquaculture

Capture fisheries have long been an important component of world food production, and the production of capture fisheries — thanks to gradually improving fishing technology — increased with the growing population until the mid-1980s (Fig. 2). Fishing pressure on wild stocks increased and by the mid-1980s overfishing of many species led to stagnation of production. This provided the opportunity for aquaculture to expand and meet the shortfall between capture fisheries and demand. Aquaculture production has increased rapidly since the 1980s, and today the amount of edible fisheries products from aquaculture is equal to that of capture fisheries and nearly 90 percent of aquaculture production occurs in Asia. Capture fisheries production is not expected to increase in the future; it may even decline because many species are being fished beyond their sustainable limits. Thus, for the global per capita consumption of fisheries products to remain at its present level, all growth in future demand must be supplied by aquaculture

Following World War II, many international aid agencies and humanitarian NGOs began programs to encourage development and alleviate hunger and poverty worldwide. Aquaculture was promoted as a way of providing food for poor, rural, farm families. Moreover, the limits of capture fisheries were predicted (Ryther 1969) and aquaculture was hailed as a potentially large and sustainable source of animal protein that could contribute greatly to the world food system (Bardach et al. 1972). The environmental community also praised aquaculture for its potential for allowing poor rural families in developing countries to use farm wastes to produce fish for their own households as well as for sale in local markets, resulting in alleviation of hunger and poverty.

 Aquaculture was referred to by some as the “Blue Revolution” — a term no doubt inspired by the “Green Revolution,” which applied to the development of better varieties of crops that began with Dr. Norman Borlaug’s research on disease-resistant, high-yield wheat strains in Mexico in the 1940s and spread worldwide in the 1950s and 1960s. Environmentalists were not enthralled by the Green Revolution despite greatly increased world food production. The new agricultural technology was highly dependent upon fossil fuels, required large inputs of other natural resources, and caused many negative environmental impacts. It also favored large farming operations that were considered by environmentalists to be “industrial” agriculture; a similar association was ultimately made for aquaculture.

Read the rest of this article in the December 2013 issue of World Aquaculture Magazine here