Since January, the cost of eating at home in the United States has gone up 5 percent. Depending on the kind of bread you like, its price has gone up anywhere from 31 to 50 percent in the last year. But it could be worse:

• In Egypt, President Hosni Mubarak has put his army to work baking bread.

• In Bangladesh, a two-kilogram (about four and a half pounds) bag of rice, enough to feed an average family of four for a day, now costs that family half of its daily income.

• In Mexico, the price of tortillas, the corn-based staple of nearly everyone’s diet, has quadrupled in the last two years.

• Burkina Faso faces a general strike because of the price of food. Other African nations — including Cameroon, the Ivory Coast and Mozambique — have seen food protests turn into near riots, as has the Philippines. Haiti is having full-fledged riots.

The world is on the brink of a food crisis. In some places, it’s over the brink. Robert Zoellick, the head of the World Bank, said last week that “while many are worrying about filling their gas tanks, many others around the world are struggling to fill their stomachs, and it is getting more and more difficult every day.”

Serious world leaders still can head off catastrophe. But they better hurry.

The deputy U.S. ambassador to the United Nations is a soft-spoken career diplomat named Alejandro D. Wolff. In a meeting with the Post-Dispatch editorial board last week, Mr. Wolff said that 10 years ago, attitudes toward solving world hunger were more hopeful than they are today.

“But the world has changed in the last 10 years,” he said. “We have the problems of climate change. Of drought. Of limited resources. And food prices. Conflict will emerge. If the United States has an interest in a stable world, it has to devote more resources to the health and security of the world. The irony is that while the situation is dramatically different than it was 10 years ago, it’s not different than it was 30 or 40 years ago.”

That was before “The Green Revolution” transformed agriculture, creating heartier seeds and more abundant yields. Doomsayers like Paul Ehrlich, whose 1968 book “The Population Bomb” predicted worldwide famine by 1985, disappeared into academe.

Mr. Ehrlich was back last week, writing in a letter to The New York Times that the world will add 2.5 billion people in the 21st century and that they “will have a disproportionate impact on the environmental systems [water, energy, fertilizer] supporting agriculture . . . while dealing with climate change that threatens agriculture from many different directions. No economist, indeed no human being, should be ignoring those factors.”

In the short run, Mr. Zoellick of the World Bank called for $500 million in emergency food aid from developed nations to offset rising grain prices. Finance ministers from the G-7 industrialized nations are meeting in Washington this weekend. The crisis in the world financial markets is at the top of the agenda; the food aid request should be next.

The United States should lead the way. Five hundred million dollars is what this country spends on the war in Iraq every 30 hours. Feeding the world would do a lot more to win friends and influence world opinion than 30 hours in Iraq.

The money could come from trimming the $13 billion in subsidies in the new farm bill. Congress faces an April 18 deadline for sending the bill to President George W. Bush, who has threatened to veto it. At a time of record grain prices, it makes no sense to subsidize grain farmers.

The nation also must increase its assistance to plant research with an eye toward stimulating a second Green Revolution. St. Louis’s plant research industry is at the forefront of that effort.

America also should rethink carefully its new-found commitment to corn-based ethanol. Mr. Zoellick said last week that half of corn’s price increase was the result of a third of the U.S. corn crop being turned into ethanol.

The moral calculus here is not difficult. Using that much corn for ethanol may knock a few cents off the price of a gallon of gas. It means the country imports slightly less oil from Arab nations. Those are social goods. Feeding hungry people is a social better, one that will do far more for the long-term security of the United States.