The prices of food, especially grains, have risen sharply in recent months, sending grocery bills higher in developed countries and putting basic foodstuffs out of reach in some Third World nations.

The World Bank estimates the price of food staples has risen 80 percent since 2005.

The burning of corn for fuel is one culprit - one for which the United States is largely to blame.

This week an American economist and adviser to the United Nations urged the European Union and the United States to rethink their emphasis on biofuel production intended to reduce the burning of fossil fuels.

He cited figures that the United States is diverting up to a third of its corn crop to fuel. He cited that trend for worldwide food scarcities and said U.S. ethanol production is to blame for 20 percent of the world's food price increases. The U.S. Department of Agriculture agrees, although the ethanol industry says, predictably, that biofuels account for just 4 percent of the jump in prices.

The U.S. Energy Independence and Security Act requires production of biofuels to increase fivefold by 2022. But when it comes to corn ethanol, this mandate would reduce dependence on foreign oil far too little to justify its effects on food prices and shortages.

And its effects on global warming are practically nil. That's because the production of corn ethanol takes nearly as much energy from oil as it yields in clean fuel.

President Bush and Congress are enamored with corn ethanol largely because of the political clout of big agribusiness, not the potential of the stuff to curb carbon emissions and global warming.

There are other events and patterns contributing to food shortages and price increases, including drought in Australia and other changing weather patterns that hurt food production. The rising cost of oil is making farming and transportation of food more expensive.

It's a complicated and complex problem with interrelated causes. But it's clear that continuing the current headlong rush to embrace all types of biofuels without considering the consequences of famine and economic and political upheaval is shortsighted indeed.