Last week we learnt that there are now 1 billion hungry people in the world, more than ever, albeit a smaller proportion of the population than in the 1950s. I found this debate from the New York Times a useful guide to how to respond. On the one hand, it would be absurd to condemn millions to malnutrition because we don't like high-tech farming in Europe. On the other hand, genetic modification has delivered very little for poorer countries so far: herbicide-tolerant maize and soybean varieties, yes, but none of the drought-resistant crops that the biotech companies promised.
Beyond the biotech dichotomy, most contributors recognized that the solution to the food crisis will involve a combination of technologies, including some that don't exist yet. High-input farming depends on natural gas, which won't be around forever; water is running short in many grain-growing regions; a strictly organic world food system would be a disaster for forests, but many techniques from organic farming are useful and should be spread. It would probably help if the NGOs and corporations stopped insulting each other and worked together for a change.
If I could contribute to the debate, it would be on prices and the signals they send. High food prices are in general a disaster for development, but we need higher prices for meat, fish and air-freighted vegetables for richer people (not just rich countries) to change their destructive eating habits. We need to tax water and energy use in such a way that basic grains and vegetables are cheap enough for everyone, but beef becomes an expensive luxury for the Americas, Europe and Australia just as it is for the rest of the world. A serious carbon tax would stop us agonising between strawberries grown in Dutch greenhouses or flown from Kenyan orchards: they will be too expensive to eat anytime they're not in season.
In the absence of carbon and water taxes, more information can help: just publishing the emissions associated with beef burgers led 20% of diners to switch to chicken or the veggie option, according to this photo essay. Ultimately, though, the most powerful information is provided by the price.