To what extent are biofuels, like corn ethanol, a part of the problem here? BOURNE: Sure. Well, this has been a hugely controversial issue because we had these huge subsidy programs from the government that came in to kickstart the biofuel industry. And these are - this is basically - in the United States it's ethanol made from corn and it now takes up 40 percent of the U.S. corn crop every year. So it's an enormous amount of land devoted to basically feeding our cars. We also make biodiesel out of things like soybean, canola, rapeseed, which is more popular in the United States - I mean, sorry, in Europe where about half the cars run on diesel. So over there they've had a huge, like, 8 to 12 percent of their arable land devoted to biofuel crops, canola and sunflower seeds, things like that. And even though the biofuel industry disputes this hotly, most of the economists in the world, between the World Bank and the IMF and the OECD, point their fingers squarely at biofuels as having a major impact on driving up food prices around the word. DAVIES: And the reasons that's happening is that as gasoline prices go up, as crude oil prices go up, that provides an incentive for farmers to make money by growing. So you essentially now have food prices linked directly to energy prices. BOURNE: Exactly. So now grain prices, especially those that are related to biofuels, are directly related to the price of - of the extremely volatile price of oil. So now we've endured some nice low oil prices over the last few years, but anyone who thinks they're going to continue is probably going to be in a rude awakening. So as soon as energy prices start to go back up, you're going to see rises in grain prices because of this direct connection between fuel and biofuel. DAVIES: The other side of the equation in this problem is how many mouths there will be to feed in coming decades.