Hunger is due to more than food shortages. Political and economic factors are crucial. Countries with strong distribution systems can often feed people even during severe shortages. In countries without systems, however, even small shortages can lead to starvation. Nobel-winning economist Amartya Sen argues that no democratic country has ever had a famine. That's because leaders know that their jobs could depend on how well they feed their people. Freedom of the press, moreover, helps everyone know how the government is handling things. Dictators, in contrast, can hide failures to get food where it's needed.

Weather is the wild card of farming. Even small shifts in temperature, rainfall, and sunlight can drastically affect a farmer's crops—and the world's food supply. There are other significant causes for food shortages, such as losing farmland to erosion and urban sprawl. All of this is bad news on a planet with more than 6 billion people, nearly 14 percent of whom don't get enough to eat.

Malnutrition is the leading killer of children. Source: World Health Organization (WHO)

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Computer models predict how food production may change in the Southeast. Source: U.S. Global Change Research Program

What will happen to food supplies when the climate changes on a global level? And if the world population doubles in the next 50 years, as many experts expect, will we be able to grow enough food? Some scientists theorize that wheat crops might actually increase. But rice—the world's number-one food crop—may decrease. Computer modeling leads some researchers to fear that worldwide food production will decline, driving up prices.

Global warming might disrupt food production in other ways too. Rising sea levels may flood farmland in coastal areas. Drenched with salt, the soil would lose its ability to sustain crops. And surges of ocean water into rivers could wipe out huge numbers of fish. Swelling oceans could also wreak havoc on supplies of freshwater, sharply limiting farmers' ability to irrigate their crops. "Climate," according to an old saying, "is what you expect. Weather is what you get." Farmers—and those who depend on them—have lots of practice coping with what they get. But it's a new and daunting prospect to feed a hungry world when you don't even know what climate to expect.

click to enlarge image Rising temperatures will dramatically shrink coffee production in Uganda. Source: United Nations Environment Programme