Population growth has also triggered a new phenomenon--urban agriculture. In the past few decades, urban agriculture has been transformed from a pastime into an important income-generating activity involving millions of urban dwellers. In cities and towns, as in the countryside, women grow much of the food consumed by their families.

Accurate figures for the number of people involved in urban farming are not available, but according to the United Nations Development Programme (UNDP) they may number several hundred million. They are found throughout the world, in both developing and developed countries, but their greatest contribution to food security is in the poorer developing countries, where poor people spend up to 90 per cent of their disposable income on food and fuel.

Urban agriculture comes in all shapes and sizes, from the small-scale farmer who scratches out a living on as little as 200 square metres, to the household garden of 20 square metres growing food for the table. Urban farmers raise fish, shellfish and aquatic plants in small tanks, ponds, sewage lagoons and estuaries; use vacant city lots and areas around public buildings and airports to grow vegetables and fruit; keep guinea pigs, rabbits or chickens in bookshelf cages hung on walls; grow vegetables without soil, using hydroponic techniques, on roofs, terraces, patios and stairways; and use the land between urban areas and along roads and railways to grow trees for fuel and fruit.

Consider the following examples:

• In Dar-es-Salaam one in every five adults in the city is a farmer.
  
• Cairo reports 80,000 animals within its city limits; -most tended by women and children.
  
• Over 60 per cent of the peri-urban area of Bangkok is given over to vegetable production. Women and children are the main producers.
  
• In Port Moresby, Papua New Guinea, nearly 70 per cent of the urban gardeners are women.

Within the boundaries of Hong Kong, the city produces two-thirds of the poultry, one-sixth of the pigs and close to half the vegetables consumed by its citizens. Singapore, with 10,000 licensed farmers, produces one-quarter of all its locally consumed vegetables. New York City, through an agency called Green Thumb, makes more than 1,000 vacant lots available to community groups who want to cultivate vegetables. Berlin has more than 80,000 community gardeners working small plots of land set aside for horticulture.

Food from urban gardens is not factored into official agricultural statistics, which measure mostly commercial and export crops. The fact is that millions of people, most of them women, have managed to produce food in towns and cities without any official recognition or support.