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Feeding a growing human population

25 September 2014


Enough space to produce food on the Earth where the climate is currently becoming less conducive to agricultural production will probably combine with few alternative sources of food production to create new conflicts. In addition, several types of alternative energy production compete for the available land which also affects food production. Already in 2006 the USA used 20 per cent of its maize production to produce ethanol as fuel. Although there are other alternatives for the production of biofuel, and new techniques are constantly being developed, the application of such techniques require careful planning so as not to harm the production of food for a growing human population.

Humans almost became extinct as little as 70 000 years ago when a major climate change event in Africa, which became cold and dry, severely threatened the food that was available to these hunter-gatherers that were still confined to Africa. Humans survived by living along the South Cape coast where they switched to a diet of marine resources and utilised the bulbs and tubers of the fynbos. When the climate of Africa again became more wet and moderate, humans started to move north along the east coast and later the Rift Valley to cross the Arabian Peninsula into Europe and Asia for the first time.

It is being predicted that there will be some 9 billion people on the Earth by 2045. This populaion explosion has only occurred in the past 1000 years despite humans having learned to produce their own food by becoming pastoralists some 11 000 years ago. Although pastoralism improved the diet of humans, geographic and transportation isolation still limited population growth. The human population remained constant for another 10 000 years before improved medical care and efficient transportation started to increase life expectancy and became the catalyst for the human population explosion.

When pastoralism developed, the food resorces of the world had to feed 0,05 people per km2 as opposed to the 54 people per km2 that is currently required. With traditional agriculture, famine is already a reality in many regions. Should climate change increase the mean temperature of the Earth by just another 2°C it would decrease grain production in the world by some 40 per cent. In addition, the human population in regions such as Europe and the USA is declining while that of Africa and Asia is increasing.

The reality is that it is already too late to prevent the middle generation of 2035 from being born, and such futile arguments only become of acadmic interest. It is expected that by 2050 Africa and Asia will be home to more than 50 per cent of the world’s humans. To feed them will require innovative, lateral thinking and planning, and the optimal use of all the natural resources. This will include at least the following:

Rainfall is vital for the production of food and all the rain that is received should be used as optimally as possible. Large parts of South Africa are arid and yet we still allow most of the rainwater to flow away to the sea. Yet, an impervious surface such as the roof of a house, a corrugated iron platform or one of cement and stone can allow the harvesting of four times the annual rainfall in litres of water for every 4 m2 of surface area. This water can be stored for use.

There also appears to be some resistance to the genetic development of better food resources. Yet, not a single natural food resource has remained genetically unchanged over time. They have often developed under different climatic regimes, may no longer be adapted to the current circumstances, can probably no longer yield enough food to feed the human population of the world and require continual adaptation and a change in thinking.

It is currently expected that 87 per cent of the people in the world will be living in urban areas by 2050 as opposed to 52 per cent in 1950. This will create long delivery chains which can be solved partially by the concept of vertical farming. This approach is an attempt to produce food closer to the consumer without uitising additional land. With vertical food production the emphasis shifts from the lateral production of food in rural areas to their vertical production in urban areas. It is already being done in several cities in North America and Europe.

Vertical food production can be done in high-rise buildings in any city. Each building functions as a giant greenhouse where the lighting, water provision and climate are controlled by computers on every level. Greenhouses require as little as 10 per cent of the water and 5 per cent of the surface area compared with rural land to produce the same unit of food. Vegetables and fruits are produced on the upper levels with the aid of organic fertilizers which are made from urban waste. The controlled environment prevents the impact of insects, rodents and fungi, while power is produced by solar panels on the roof or by burning methane gas. Sewerage water is treated and purified for irrigation and any water that evaporates is collected, cooled and recirculated. Plant and animal waste containing nutritional elements are used to feed animals such as poultry, pigs and fishes on the lower levels of the building. Nitrogen is extracted from the waste on successively lower levels, and earthworms are used to change excess organic waste into compost.

www.leopard.tvIt is estimated that a vertical food production unit on 30 levels and 1.32 ha of land will be able to produce the equivalent of food that will require a conventional farm of 420 ha, and that such a unit will be able to feed some 50 000 people. Vertical food production will allow land that is currently being used to grow food crops to be switched to the production of large domesticated livestock and wildlife. It will also prevent natural catastrophes such as droughts, fires, floods, hail, pests and other disasters to influence food production. The basic technology already exists and a wider application of it depends on reaching a critical phase in the production of food in the world. The final requirement then becomes issues of survival and will power.

Large areas of South Africa are marginal for crop and livestock production. Yet southern Africa has numerous wildlife production units which can also be used for the production of animal protein. However, the market for the meat of the large, wild herbivores has stuttered along and does not seem to get off the ground despite such meat being of superior health quality than that of intensively produced domesticated livestock. There are still no certified abattoirs for the meat from wild herbivores in the Limpopo province which contains almost 50 per cent of the wildlife ranches in South Africa, and there are currently only eight such abattoirs in South Africa for preparing the meat of large, wild herbivores for export to the European Union.

Cost effective transportation also influences the availability of food. Transportation systems for food that may be effective at present, may become too expensive in the future. Then some older transportation systems may become cost effective again, with rail transportation as one candidate. The key to success is in accessability and efficient cooling systems. The advantage of vertical producion units is that it excludes the problem of transportation because the food is being produced where the consumers live. In the north-eastern parts of the USA the consumers are already increasingly buying their food from local producers who are known to them.


Bloom, D E 2011. 7 billion and counting. Science 333: 562 - 569.

Marean, C W 2010. When the sea saved humanity. Scientific American, August: 55 - 61.

Stone, B and M Richtel 2009. Forging a link to the farmer who grows the food. New York Times, 27 March.

Vogel, G 2008. Upending the traditional farm. Science 319: 752 - 753.


Article by Prof J du P Bothma


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