Blue and Green: Last month, the Intergovernmental Panel on Climate Change (IPCC) published a report that said all aspects of food security were at risk of being affected by global warming. Other studies have concluded that people can help matters simply by eating more vegetables and less cheese and meat. Growing your own vegetables might therefore help the environment, but can it save you money? We know that 250g of tomatoes can cost around 1.50 in the supermarket, while a small packet of seeds can be purchased...