Garth George says he has read all about the food crisis but remains unconcerned. He suggests we can develop new methods of food production before parts of the world face starvation. Wrong. Large numbers of people are already starving. Surely we are concerned about that.

Tonight, more than 850 million people will go to bed hungry. Tomorrow won't be any better. Hunger is already a leading cause of death worldwide, killing an estimated 10 million people every year - more than Aids, tuberculosis and malaria combined.

In Africa, Asia, the Middle East and Latin America, many people already spend 80 cents of every dollar they earn on food. The impact of recent record highs in prices of rice, corn, and wheat on these people - the world's poorest - is becoming increasingly clear.

Estimates by the Asian Development Bank put 300 million people in India, Bangladesh and Pakistan alone at risk of starvation due to the rising prices. In Senegal, Oxfam staff have seen evidence that the usual "lean season" is coming on earlier as a result of price rises.

There are lower stocks in markets that usually have surpluses at this time of year, and people are eating alternative food and selling their animals already.

Senegalese pastoralists are buying food earlier than usual and Mauritanian herders are coming over the border in search of pasture. This is having a direct impact on livelihoods and there is increased tension between different groups for natural resources, and an increase in banditry.

The World Bank is now warning that 33 countries face potential social unrest because of the huge hike in food and energy prices. Food riots have already broken out in countries such as Egypt, Tanzania and Mexico as people get hungrier.

A perfect storm of factors has caused prices to rise to unprecedented levels over a very short period of time. Climate change is causing increasingly erratic weather - bigger floods, and more severe droughts - which is destroying or damaging crops and reducing supply.

Higher oil and energy prices are increasing the cost of inputs like fertiliser while transport costs soar because of expensive fuel. Demand for biofuels - energy made from crops like corn and sugar - means that hungry people are competing with hungry cars for the same output.

Growing populations in India and China are eating more meat - which requires huge quantities of grain for animal feed. Finally, speculation on commodity markets, encouraged by high prices, is further upping the pressure.