A new paper published this week in Science, written by Britain's chief scientific adviser John Beddington along with nine other experts, outlines a way this could actually be done. The catch? Doing so would require "radical" changes to the current global food system. The paper's a great synthesis of a wide range of different food issues, and I'll just pull out the main ideas:
Boosting crop yields: If the supply of farmland is ultimately finite, then boosting yields is the only way we'll get more food.
Stop tossing out so much food: The study estimates that 30 percent to 40 percent of the world's food is thrown out each year.
Fewer hamburgers: Can't imagine this one will go over well, but the authors do suggest that people will probably have to reduce their meat consumption slightly to feed nine billion people. This doesn't mean going vegetarian.
A slew of green technical stuff: Of course, all those other measures will only go so far. There are also some serious threats to the long-term sustainability of agriculture lurking out there. Global warming's a big one. But then also water shortages due to over-extraction. Soil degradation due to poor farming techniques. Loss of biodiversity due poor management. The fact that fisheries are being ravaged (so something like a cap-and-trade system for fish could help here). A lot of the fixes here are dry and technical, and they tend to get discussed as wonky enviro ideas that might be nice to do but aren't essential. Except that, as the Science study makes clear, they really are crucial—at least if all those nine billion people want enough to eat.
Not Food Crops and Farmland to Fuel Vehicles: It's probably going to be hard to find enough food for nine billion people if we're still diverting vast swaths of farmland for crop-based ethanol. (Though maybe by then we'll have moved on to algae fuels or electric cars or some other fancy technology.)
It's a fascinating, crucial topic -- one with that tie directly into humanity's other top crises: climate, biodiversity, fresh water. We sure live in interesting times...