WS MoreOrLess: The future of food

"In the next 40 years, humans will need to produce more food that they did in the previous 10,000," claimed a recent edition of The Economist. Ruth Alexander and Hannah Moore look at whether this is true. With the world's population expected to reach 9 billion by 2050, how confident can we be that everyone will have enough to eat? This programme was first broadcast on the BBC World Service.