Food security is once again prominently on the global agenda. While the world’s population growth rate continues to decline, the emergence of a global middle class is pushing up demand for more meat, milk, eggs, fats and oils, sweeteners and fruits and vegetables. This more resource-intensive diet is emerging alongside increasing competition for land and water from production of biofuels and from urbanization. At the same time, agricultural productivity growth could be slowed because of reduced research and changing climate. These issues are likely to figure more prominently in both trade and climate change negotiations going forward.

Food security means reliable, affordable access for all people at all times to a diet that is calorically and nutritionally adequate for a healthy, active life. The traditional threat to food security is hunger. People who are chronically hungry lack the income to afford an adequate diet. Crisis hunger arises when normal access to food supplies is disrupted by poor harvests, civil disorder or erosion in buying power from rising prices. Malnutrition is especially a problem for pregnant women and children with special demands for growing minds and bodies.

While it has been an acknowledged goal to reduce both the absolute number and the share of the world’s population suffering from chronic hunger, the recent spike in staples food prices has pushed the number of chronically hungry from 800 million to one billion. Some 30 countries imposed price or export controls in 2008 in response to hunger crises. And higher prices have aggravated malnutrition among vulnerable populations.

All of this has offset the good news from the latest population forecast, which shows that fertility rates are falling faster than expected, pointing to a stabilization of the world’s population around 9.2 billion at mid-century.

A second tier of food security arises from the increasing globalization and modernization of the world’s food economy. Expanding trade and increasing dietary diversity are making supply chains longer and more complex. This brings new challenges to ensuring food safety and dietary health: protecting against the rapid migration across borders of plant or animal diseases; strengthening defenses against tainted foods; and improving dietary intake and food choices to slow the spread of obesity, which now affects one billion people.

A third level of food security is embedded in the notion of sustainable development. It takes more land and water to produce animal protein or calories from fats and oils than from grains and root crops. As rising incomes increase demand for such foods, the resource-intensity of the diet presses against limited endowments. The problem is compounded by the fact that most of the anticipated population growth is expected in Sub-Saharan Africa, where much arable land is seriously degraded and unproductive, and South and East Asia, where population densities already strain agricultural resources and biodiversity. Production of biofuels and the threat of productivity-depleting climate change in many of these regions aggravate this sustainability challenge.

In other words, food security represents a three-front challenge. The world is still a long way from ending the scourge of hunger. Increasing integration of economies brings with it the new risks of rapidly transmitted diseases, poor diets and embattled food safety regimes. And resource imbalances in the face of concentrated demand growth in environmentally challenged geographies imperil the sustainability of the global food system.

As the world gears up to meet this food security challenge, several themes recur and deserve emphasis. First, it will be increasingly important to take a systematic approach to addressing food-security concerns. A more integrated food system means that hunger issues cannot be addressed separately from safety, health or sustainability issues. They must be looked at together as parts of a global food system.

Second, the neglect of research into agricultural productivity and investment into rural infrastructure that has characterized the past few decades needs to be reversed. This is especially true for developing countries, where farm productivity is low, resource stresses high and demand pressures growing. Investments in these two areas, moreover, may stimulate a more broadly-based, more equitable pattern of economic development.

Finally, international negotiations on trade issues and on climate change must come to terms with their past neglect of agriculture. The economic and policy distortions in the world’s agricultural economy are a multiple of those existing for industrial goods or services. A serious effort to catch up with the reform in these other areas is critical to enhanced food security. On climate, agriculture is known to be both a major source of greenhouse gases and a potential contributor to mitigation strategies, and effective adaptation strategies will need to ensure that food security is preserved.

All of which means that securing food security will prove a major priority and a significant policy challenge.