A lot of my friends are into local food security, which means eating food that comes from near where you live. "Local" is a relative term: your garden rates highest, followed by farms in your immediate vicinity. Food grown in your state is preferable to food grown on the opposite end of the country. This doesn't mean you have to give up foreign-grown favorites like pineapple or coffee. It means you are trying to skew your diet towards local nutrition.
This food security trend got a lot of push from fears about "peak oil," the theory that sooner rather than later the total amount of oil produced in the world will go down. There is evidence for and against this theory, but the strongest fact is that the USA used to produce plenty of oil for its own needs: now it can't. As newer oil fields age and people in India and China are able to compete economically to buy what oil is produced, prices are bound to rise in the long run. Which means the cost of producing food (tractors = diesel) and of moving it around will go up.
But there are political problems with food security as well. In the past many governments have simply seized food produced in rural areas to keep people from rioting in urban areas. In some cases farmers starved, unable to eat the fruits of their own labor. Raiding peasants for their food is an ancient predator tradition; don't think it can't happen here.
Ever since Malthus put forward his famous "Essay on the Principle of Population" in 1798, technology has been proving Malthus wrong. Malthus believed that populations increase at a geometrical rate but food production only increases at an arithmetical rate (we'd say linear rate), which means food production can't keep up with population growth. While there have been regional famines since 1798 (notably the Bengal starvation in India in World War II where as part of the British war effort, several million Indians starved to death when their grain was diverted), globally production has kept up with population.
But that does not mean that Malthus was wrong in general, he just happened to make his prediction before farming became mechanized, then petroleum-based, then extended by the great revolution in genetics.
Now food is in short supply. I've heard socialist types repeat the old saw that there is no food shortage, just a distribution problem. That is no longer true. Recently the run up in the price of corn (because it is being used to create ethanol, shades of the Bengal starvation) has caused Mexicans to go hungry. Their local production was undermined by NAFTA back in the 1990's; now the corn imported from the USA nearly doubled in price.
You and I may disagree with the politics and religion-of-the-markets of The Economist, but in terms of reporting they are the best. On page 98 of the January 27-February 2, 2007 edition check out the commodity-price index graph and story. Food prices in general, in global markets, are up about 30% from where they were in mid-2004. That will mean hungry people, perhaps dead people. The prices are high because there is not enough food to go around. This year it is because of the drought in Australia affecting their wheat crop and the conversion of corn to ethanol in the US. Prices may come down at times, but short of another technological miracle, population has finally outpaced the food supply.
Fish stocks have collapsed. Soil has been degraded. Rising sea levels will cause flooding and salt water intrusion.
And yet people keep breeding.
If the human race does not consciously control our numbers, nature will eventually control them for us. In the old cruel ways: disease, starvation and war.