The rising price of food is sending shivers down the spines of many world leaders who are aware that the skyrocketing prices have the potential effect of causing a "real economic and humanitarian tsunami in developing countries".

The World Bank estimates that food prices have increased by 83 per cent in the last three years, presenting a real risk of starvation to an estimated 100 million poor people who will be unable to afford food.

And with Africa being one of the world's poorest continents, it is most likely to feel the pinch more and on a wider scale. Already, there have been food riots in Egypt, Ivory Coast, Senegal, Ethiopia and Burkina Faso. To underline the seriousness of the food crisis, African Finance ministers said in a statement that the rise in the cost of food threatened the continent's growth, peace and security.

However, the shortage is not peculiar to African nations. There have been food riots in Indonesia, the Philippines and Haiti. In Haiti, the riots led to the death of five people and the prime minister's resignation.

The food shortage has become such a weighty issue that United Nations Secretary-General Ban Ki-moon has termed it a global crisis. UN Food and Agricultural Organisation chief Jacques Diouf says immediate efforts to cushion the blow should focus on helping farmers in developing countries grow more crops. Josette Sheeran, the World Food Program's executive director, has said that requests for food aid are already coming in from countries unable to cope with the rising prices.

But why is the world facing a food shortage?

Global population growth is one of the factors being blamed for the high food prices. Food production used to increase at a higher rate than population growth thanks to research in crop and animal production and modern methods of farming.

However, some scientists feel that the population growth rate has caught up and could even surpass food production rates if urgent measures are not taken.

Prices of the most basic foodstuffs traded on international commodity markets are increasing sharply as their demand continues to increase against declining supplies. And this is a trend expected to continue. In 2000, the world's population was 6.1 billion and the UN estimates that by 2050, the world's population will be at 9.8 billion.

The price of wheat, for example, has doubled in less than a year, while other staples such as corn, maize and soya are trading at well above their averages in the 1990s. Rice and coffee prices are at a 10-year high, and in some countries, milk and meat prices have more than doubled.

FAO and World Bank also cite the emerging economies of the highly populated countries such as India and China as playing a major role in pushing up prices. The economic growth is pushing more and more people into the middle class translating in increased demand for meat, dairy products and processed foods.

FAO research shows that in China, for example, meat consumption per capita in 1980 was 20kg. In 2007, this increased to 50kg. The increased consumption rate is pushing up prices beyond the reach of the poor.

Studies done by the United Nations Environment Programme, the world's leading environment organisation, provides a third reason for the crisis: misuse of resources is turning more acres of land which would have hitherto been used for food production into deserts.

As a result, UNEP says, irregular rainfall patterns and flooding are becoming a common feature in the world's major food producers, including developing countries in Africa, thus affecting agricultural production.

Climate change and its impact on general livelihood in the world has forced developed countries to look for alternative sources of clean energy. The shift from agricultural production to the lucrative business of biofuels has seen food literally being used to fuel industry and automobiles. Biofuels such as ethanol are produced from renewable biological resources like corn.

In addition to trying to reduce pollution, developed nations sought biofuels to counter high oil prices. Oil prices are being driven up by increased demand from industrialised and industrialising countries, against declining supply caused mainly by resource depletion and political instability in source markets.

These high prices are mostly felt in developing countries where the system of food production and distribution is heavily dependent on oil and other fossil fuels for processing, packaging, storing and transportation.

However, not everybody in the world is complaining. The Bretton Woods Institute says the main beneficiaries of the current situation are farmers in rich and emerging market nations like the US, Brazil, Argentina, Canada and Australia, who are making record profits for their harvests.

For developing countries, the World Bank has called for targeted subsidies to help the poor. The UN's World Food Programme has already sent an appeal for $500 million (Sh32.5billion) to provide emergency food aid.