Global food prices are once again creeping up to potentially critical levels, a World Bank report has found.

Prices have risen 8 percent since December and are currently only 6 percent lower than the record highs reached in February 2011, according to the bank's Poverty Reduction and Equity group's Food Price Watch. All key staples, with the exception of rice, are more expensive, including corn, soybean oil, wheat and sugar. These increases follow four months of a downward pattern.

Although the trends are global, the impacts are highly regional. The price of rice may have declined overall, but in Kampala, Uganda, it increased by 125 percent. Buying wheat in Belarus became nearly twice as expensive. And in the poorest regions of the world, where people devote up to 60 percent of income to buying food, it can mean the difference between eating or skipping a daily meal.

For the world's poorest, "the implication is that you will spend double," said Jose Cuesta, senior economist with the World Bank and author of the Food Price Watch.

Oil prices, bad weather conditions and high demand for food imports in Asia were the driving forces for the price increase.

Extreme cold in Europe and Russia affected wheat prices. Hotter-than-normal temperatures in Brazil and Argentina contributed to increases in sugar, corn and soybean prices. The drought in the U.S. Southwest also contributed to higher cereal prices. Strong economic growth in Asia, weather conditions and a weak dollar led to the continent's larger food imports, said Cuesta.

Factors besides the weather

Cuesta said adverse weather conditions in Australia could wreak havoc on future wheat supplies prices, and the country is one the World Bank is tracking for clues on future food prices. A recent scientific study found that climate change will be the biggest driver of corn price volatility in the future (ClimateWire, April 23).

The Sahel region of Africa is likely to be prone to food shortages this year, according to a global food policy report by the International Food Policy and Research Institute (IFPRI) (ClimateWire, April 24).

A shortfall in funding to the region could put more than 15 million people across nine countries at risk, say humanitarian groups. The Sahel has suffered from drought and insect infestations.

Cuesta takes a slightly different approach to biofuels' effect on food prices than many food policy organizations have followed. Biofuel policies, like the renewable fuel standard in the United States, don't drive prices up, he said. However, a slower pace of ethanol production in the United States has helped buffer potentially higher food prices.

When it comes to the role of biofuels, "to be honest, we don't know," said Cuesta. "We know it's a factor, but we don't know how important it is."

Many food-related organizations, including IFPRI and the U.N. Food and Agriculture Organization, have attributed biofuel policies in many countries to increasing food prices. Biofuels skeptics say boosting production can create a competition between land for fuel and land for food, disrupting agricultural markets.

What is raising the price of corn?

"This is not, at this time, contributing to the additional increase in food prices," Cuesta added. Food prices are much more closely linked to increases in the barrel price of crude oil, according to Cuesta, which dictates costs for fertilizer, transportation and incentives for the switch from fossil fuels to biofuels.

The argument that oil, not renewable fuels, affects food prices has long been the biofuel industry's response to critics.

"There is only one common input cost for all food, and that is energy prices," said Bliss Baker, spokesman for the Global Renewable Fuels Alliance, in an email. "The impact of biofuels production on food prices has been exaggerated and overblown, but fortunately, there is ample data today that points to the primary driver of food inflation -- oil prices."

Corn ethanol production has slowed down to keep pace with the renewable fuel standard, which limits conventional biofuels from corn to 15 billion gallons per year, said Matt Hartwig, director of public affairs for the Renewable Fuels Association. The current production level is about 13.5 billion gallons.

The commonly used standard for measuring food prices is the U.N. Food and Agriculture Organization's FAO Food Price Index. For the four-month period observed in the World Bank report, the FAO Index reports a five-point -- 2.5 percent -- increase in food prices. The different numbers from the two organizations signify a variation in the importance given to difference commodities, said Nancy Morgan, FAO's liaison to the World Bank.

"The most likely reason that the Bank index is going up higher is that oilseeds have a higher weight in their index," she wrote in an email. "FAO includes a broader array of commodities, such as dairy and more meat types."