Another 10 vs 70 statisitc I have seen a number of times is the percent of income spent for your average American (I believe defined as a household income of $55,000) vs a family in the developing world. So, 10% spent on food for Americans vs. 70% for people in poor countries. So, what seems preposterous to you or me is everyday reality for billions of people.

I think much of the press about that G-20 meeting referred to in the OP use the wrong headlines. It's really not food shortages that are the immediate problem that they were meeting to discuss, it's the rapid price volatility that is crushing so many of the world's poor lately. I have read that 98% of the world's hungry are from developing countries, and if they have to spend most of their income on food, you can see how sudden spikes in food prices can be catastrophic, especially for growing children.

While it's true that the total global food production is enough to theoretically feed everyone, there really are food shortages in many areas above and beyond the fact that food is getting too expensive for people to buy. When a major wheat producer like Russia bans exports this year so its own people don't riot over rising food prices, there isn't necessarily a lot of reserves to take up the slack in the marketplace, which is partly why wheat prices doubled in a short time. Countries that can pay get the wheat, and those that can't, do without, or do with less. Over time, higher prices should lead to more production, but that takes time and people still have to eat in the meantime.

We are lucky in that the raw cost of food is only a percentage of the price we pay, so spiking food commodity prices don't cause such dramatic spikes in the final price of food for us. However, that may change if economic conditions take a precipitous nosedive. It would probably only be a temporary condition, but it's a good reason to have longer-term food supplies to ride out such disruptions. Actually, on a global level, better food reserves would allow poorer countries to also ride out situations like this, similar to how the IEA announced releasing petroleum from its strategic reserves in response to high global oil prices, but food reserves are quite thin in most countries nowadays. Gardening could likewise provide a cushion through turbulent times.