The price of food is soaring. The threat of hunger and malnutrition is growing. Millions of the world's most vulnerable people are at risk.

An effective and urgent response is needed.

The first of the Millennium Development Goals, set by world leaders at the U.N. summit in 2000, aims to reduce the proportion of hungry people by half by 2015. This was already a major challenge, not least in Africa, where many nations have fallen behind. But we are also facing a perfect storm of new challenges.

The prices of basic staples -- wheat, corn, rice -- are at record highs, up 50 percent or more in the past six months. Global food stocks are at historic lows. The causes range from rising demand in major economies such as India and China to climate- and weather-related events such as hurricanes, floods and droughts that have devastated harvests in many parts of the world. High oil prices have increased the cost of transporting food and purchasing fertilizer. Some experts say the rise of biofuels has reduced the amount of food available for humans.

The effects are widely seen. Food riots have erupted from West Africa to South Asia. In countries where food has to be imported to feed hungry populations, communities are rising to protest the high cost of living. Fragile democracies are feeling the pressure of food insecurity. Many governments have issued export bans and price controls on food, distorting markets and presenting challenges to commerce.

In January, to cite one example, Afghan President Hamid Karzai appealed for $77 million to help provide food for more than 2.5 million people pushed over the edge by rising prices. He drew attention to an alarming fact: The average Afghan household now spends about 45 percent of its income on food, up from 11 percent in 2006.

This is the new face of hunger, increasingly affecting communities that had previously been protected. Inevitably, it is the "bottom billion" who are hit hardest: people living on one dollar a day or less. When people are that poor, and inflation erodes their meager earnings, they generally do one of two things: They buy less food, or they buy cheaper, less nutritious food. The result is the same -- more hunger and less chance of a healthy future. The U.N. World Food Program is seeing families that previously could afford a diverse, nutritious diet dropping to one staple and cutting their meals from three to two or one a day.

Experts believe that high food prices may be here to stay. Even so, we have the tools and technology to beat hunger and meet the Millennium Development Goals. We know what to do. What is required are political will and resources, directed effectively and efficiently.

First, we must meet urgent humanitarian needs. This year, the World Food Program plans to feed 73 million people globally, including as many as 3 million people each day in Darfur. To do so, the program requires an additional $500 million simply to cover the rise in food costs. (Note: 80 percent of the agency's purchases are made in the developing world.)

Second, we must strengthen U.N. programs to help developing countries deal with hunger. This must include support for safety-net programs to provide social protection, in the face of urgent need, while working on longer-term solutions. We also need to develop early-warning systems to reduce the impact of disasters. School meals -- at a cost of less than 25 cents a day -- can be a particularly powerful tool.

Third, we must deal with the increasing consequences of weather-related shocks to local agriculture, as well as the long-term consequences of climate change -- for example, by building drought and flood defense systems that can help food-insecure communities cope and adapt.

Last, we must boost agricultural production. World Bank President Robert Zoellick has rightly noted that there is no reason Africa can't experience a "green revolution" of the sort that transformed Southeast Asia in previous decades. U.N. agencies such as the Food and Agriculture Organization and the International Fund for Agricultural Development are working with the African Union and others to do just this, introducing vital science and technologies that offer permanent solutions for hunger.

Simply improving market efficiency can have a huge effect. Roughly a third of the world's food shortages could be alleviated to a significant degree by improving local agricultural distribution networks and helping to better connect small farmers to markets.

But that is for the future. In the here and now, we must help the hungry people hit by rising food prices. That means, for starters, recognizing the urgency of the crisis -- and acting.