The energy and transport sectors are widely seen as the most harmful for the planet. But for some, the agriculture industry is even more destructive. It's responsible for as much as 30 percent of the world's greenhouse gases. Yet its role in global warming attracts much less attention. George Monbiot is a journalist and the author of "Regenesis: Feeding the World Without Devouring the Planet". He joined us on Perspective for more on why the industry is so destructive and some of the controversial solutions he proposes.