Waste that we can avoid: Twelve billion plastic bags are handed out to shoppers in Britain every year. Tesco's and Sainsbury's alone each hand out 1bn. Most plastic ends up in a landfill site. It will never biodegrade, but thanks to the biological conditions which exist in landfills, neither will organic waste such as onion clippings or hamburgers, which can remain intact for decades, 27m tonnes of it accumulating year by year. The irony of plastic waste as a serious environmental problem is that, unlike fossil fuel consumption or rainforest destruction or coral reef bleaching, it is easily solvable. Plastic is an immensely useful material. We use it, however, as though it has no downside at all. Next time you are at the check out, remember ask yourself do you need another carrier bag to take home and throw away.