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The spectre of food shortages is casting a shadow across the globe, causing riots in Africa, consumer protests in Europe and panic in food-importing countries. In a world of increasing affluence, the hoarding of rice and wheat has begun. The President of the Philippines made an unprecedented call last week to the Vietnamese Prime Minister, requesting that he promise to supply a quantity of rice.

The personal appeal by Gloria Arroyo to Nguyen Tan Dung for a guarantee was a highly unusual intervention and highlighted the Philippines’ dependence on food imports, rice in particular.

“This is a wake-up call,” said Robert Zeigler, who heads the International Rice Research Institute. “We have a crisis brewing in rice supply.” Half of the planet depends on rice but stocks are at their lowest since the mid1970s when Bangladesh suffered a terrible famine. Rice production will fall this year below the global consumption level of 430 million tonnes.

Street protests and rioting in West Africa towards the end of last year were a harbinger of bigger problems, the World Food Programme said. The global information and early warning system of the Food and Agricultural Organisation (FAO) has monitored outbreaks of rioting in Mexico, Morocco, Uzbekistan, Yemen, Guinea, Mauritania and Senegal. There have also been protests in Jakarta, the Indonesian capital, over government price increases.Population pressure and increased wealth are mainly to blame for the resurgence of food insecurity. More people are eating meat and dairy products in Asia, which increases the demand on the animal-feed industry. Milk powder prices rose from $2,000 to $4,800 per tonne last year as rising consumption of milk products in Asia coincided with shortages in the Western world. Drought in Australia has worsened the problem as have government policies in Europe and America to increase the use of biofuels.

Mounting concern about rice has prompted the Indian Government to restrict exports of certain varieties. The measure triggered a surge in global rice prices, which have risen 50 per cent in a year, according to the FAO. The rice shortage is even felt in Britain where the price of basmati, the biggest-selling variety, is rising rapidly.

Wheat is suffering even greater pressures, with prices up 115 per cent in a year. A succession of droughts in Australia has put upward pressure on the cost of a food commodity that is already in short supply. Stocks are at a 40-year low and exports are being restricted from Beijing to Buenos Aires. Ukraine started closing its door to grain exports in June and Russia set a 40 per cent export tariff on wheat in January.

Argentina has delayed the reopening of its wheat export registry until April to protect domestic supplies, and China, a net exporter of corn, rice and wheat last year, has imposed export quotas on grain in order to stem runaway food price inflation. A surge in its inflation index in December was blamed entirely on rising food prices, notably pork, which rose 48 per cent.

Farmers worldwide are worried about feed costs. In Europe pig and poultry breeders are threatening to cut production unless they are paid higher prices.

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