In the lakeside capital of the central African country of Burundi, 40-year-old Lucie Nahimana on Thursday fed her family of six "black flour," a low-quality cassava root that many here have resorted to eating because they can't afford anything else.
Thousands of miles away, in the port city of Tianjin, China, physician Ning Aimin scanned the shelves of her supermarket for yogurt, a food that was practically unheard-of here a decade ago but has become a favorite of many of China's newly affluent.
On a chilly highway outside Gualeguaychu, Argentina, 10 trucks carrying enough rice to feed 3 million people in one day sat stranded on the side of the road, casualties of a 100-day-long farm strike that's paralyzed that country's giant grain industry.
These three episodes, all on Thursday, are interconnecting pieces of what's emerged as one of the biggest challenges facing the planet: how to feed humanity in this age of skyrocketing food and energy prices.
The problem is a global one, in which a breakdown anywhere in the food chain sets dire consequences in motion and in which the root causes range from rising consumption in Asia to growing biofuel production in the United States and Europe to dwindling supplies of water in the Middle East.
"The world is running now to keep up with demand," said Abdolreza Abbassian, a grain analyst with the U.N. Food and Agriculture Organization. "Any interruption in the global picture affects supplies."
Already, some 800 million people around the world suffer from chronic food shortages, and millions more could go hungry because of the widening food crisis.
Rising food prices hit the urban poor the hardest, those who throng the slums of sprawling capitals such as Lagos, Nigeria, Manila, Philippines, and Caracas, Venezuela.
From 2007 to 2008, world prices for soybeans increased by 29 percent, while prices for wheat grew by 40 percent and rice prices jumped by 53 percent, according to a World Bank study. Food prices had stayed largely stable from 1995 until the end of 2006, the study found.
The recent price spike was the result of problems such as unfavorable weather in grain-exporting countries such as Australia and dwindling food stocks in Europe, according to the U.N. food organization. The coming year's food stocks promise to be thin as well, with floods in the U.S. Midwest and political turmoil in Argentina cutting back grain production.
Yet the problem is long-term, as the world's food-production machine fails to keep up with rising demand. The U.N. organization estimates that the problem won't go away for five to 10 years, and that's only if farmers around the world come up with new technology to increase efficiencies and boost production to meet the rising needs.
"The hope is that these high prices will inspire more production around the world," Abbassian said. "During this transition, however, people in poor countries are going to be the most affected."
That means folks such as Nahimana, who said Thursday that her monthly food budget of about $100 bought only about two-thirds of what it used to, so the family's meals are smaller and incredibly basic.
They usually eat just once a day, like most families in Bujumbura these days. Nahimana hasn't bought vegetables for several days, because soaring gas prices have made cabbage and other greens, which must be trucked in from the countryside, far too expensive.
In Burundi, where nine in 10 people live on less than $1 a day, a day's serving of rice or beans now costs more than the average daily wage.
"I know the children are not eating well, and that they go to bed hungry," the petite mother of four said. "I am afraid for their health."
Perhaps the region hit the hardest is sub-Saharan Africa, where, despite great agricultural potential, the majority of countries import most of their food. The U.N. food organization reports that of the 37 worst-affected countries worldwide, 21 are in Africa.
The crisis has exacerbated troubles in strife-torn Zimbabwe and in southern Somalia, where even locally grown corn is up to four times more expensive than a year ago, the U.N. reports.
In a report this week, the Africa Progress Panel, a group of experts chaired by former U.N. Secretary-General Kofi Annan, warned: "Unless some way can be found to halt and reverse the current trend in food prices, there will be a significant increase in hunger, malnutrition, and in infant and child mortality."
Despite the hopes of food experts, however, the world's farmers are facing an ever-tougher battle to produce more to feed families such as Nahimana's.
As panic has rippled through some corners of the global grain market, prices for grains have grown more volatile. That frightens farmers already dealing with soaring costs for fertilizer, herbicides and fuel. Some wonder whether they should plant again and risk a sudden drop in prices.
That was the dilemma of Argentine farmer Haroldo Dorn, who was manning a roadblock near Gualeguaychu in central Argentina to prevent trucks from transporting grains to markets and ports.
The farmers were protesting a recent export-tax increase targeting soybean growers, a tax hike that the government says will force farmers to share with the rest of the country their record revenue from rising grain prices.
Farmers such as Dorn, however. say that soaring expenses and uncertainty about future prices have offset those rising profits.
"The need of the world is food, but what this government wants is to keep all the money for themselves," Dorn said. "We are just barely keeping up with rising costs."
On Thursday, rain fell on Gualeguaychu for the first time since February, which usually would be a sign for farmers to start planting wheat. This time, however, there was little enthusiasm for the break in the weather, as farmers stuck to the strike.
As a result, growers estimate that Argentina's wheat production will drop by a third this year.
"Argentina is a top exporter of wheat, corn and soybeans, and the farmers' actions have been one of the big factors in high prices," said Abbassian, of the U.N. food organization.
A few years ago, such isolated problems wouldn't have caused much global turmoil, as the world's food machine had enough reserve capacity to handle occasional bumps in the road.
Those margins have shrunk to nearly nothing, however, and one of the top reasons is growing consumption in China, India and other emerging world powers.
China's meteoric growth, in particular, already has stressed world supplies of energy and raw materials. Now the country's 1.3 billion people are demanding more and better food.
Having increased the amount of meat they eat by more than one-third in a little more than a decade, China soon will be competing for grains on the international market with nations such as Egypt, Haiti, Cameroon and Indonesia, where food riots and protests erupted earlier this year.
China also is losing production capacity, with urban sprawl gobbling up farmland at a steady rate. China has been losing about 1 percent of its arable land each year this decade, and officials say that the 470,000 square miles of arable land now available are barely 7,000 square miles above the minimum needed for food security.
The effects of the Chinese consumption boom have rippled across Asia and hit hardest in countries such as Afghanistan and the Philippines, which could barely feed themselves even in the best of times.
"People eat half as much," said Paul Risley, a spokesman for World Food Programme operations in Asia.
The Philippines was once a model rice producer. But decades of neglect of agricultural policy and a population that's surged to 91 million have turned it into the world's biggest rice importer.
"They've doubled in population in 30 years," Risley said. "But they aren't even growing the amount of rice they were 30 years ago."
In booming China, Ning, the physician, was on the receiving end of the world's new food balance. Going about her once-a-week shopping trip, she presented the perfect picture of her country's new, cosmopolitan middle class.
She drove to her market of choice, Carrefour, a French chain that's China's largest foreign retailer, in her South Korean-built Kia sedan.
At the supermarket, she cruised aisles piled high with domestic and imported fruits and vegetables, including U.S.-grown lemons and Red Delicious apples, bananas from the Philippines, and oranges and durian — a fruit with a powerful rancid smell but a sweet flavor — from Thailand.
"Besides Carrefour and Wal-Mart, we also have Tesco and Vanguard supermarkets," Ning said, reeling off the names of the mega-store operators that now have a presence in nearly every major Chinese city.
Outside the New Century Square shopping center, 22-year-old Lin Hongwei prepared lamb skewers on a charcoal grill outside a noodle shop, where business was brisk, he said.
"Things are so much better now than when I was a kid," Lin said. "Salaries are higher. Food is better."
(Chang reported from Gualeguaychu, Argentina, Johnson from Tianjin, China, and Bengali from Bujumbura, Burundi.)