This story is the second of a series of 10 articles from Apolitical–an international platform for innovators in the public service and all those who care about effective government–about the best urban innovations around the world. The last one was about density. Stay tuned in two weeks for the next installment.

Those 3,000 tons every day go into landfill, where they rot and emit methane that drives climate change. And we shouldn’t just pick on New York: Roughly a third of the world’s food gets thrown away each year, which is 1.3 billion tons (or 430,000 warships.)

Cities are particularly blatant offenders because they depend on truck-, boat- and planeloads of food being transported in every morning to keep them alive. But their dense social mesh also makes them particularly able to fix the problem.

The most obvious way to do that is to make sure food that might be wasted gets given to people who want or need it. So France recently became the world’s first country to ban supermarkets from throwing away food. All unsold produce that’s nearing its sell-by date must be donated to charities or food banks. In March, Italy passed a similar law, which doesn’t penalize supermarkets who fail to do so but instead incentivizes them with tax breaks.

This idea has been turned on its head in Denmark, which has cut food waste by a quarter since 2010. In Copenhagen, a supermarket called WeFood exclusively stocks produce that has been rejected as out-of-date by the mainstream shops. It’s so popular that a second location is opening in the town of Aarhus next year.

And giving food to hungry people–surprise surprise–makes society a lot better. One of the best examples is in the English former industrial town of Leeds, where food that would be thrown away from supermarkets goes to a big state school in a poor neighborhood. The school gets enough to feed all 600 pupils a nutritious breakfast and lunch for no extra cost to itself or to parents. Because the pupils aren’t hungry or coming down off sugar rushes, there’s less truancy, they behave better, and their exam scores have gone up.

But food banks and charities also end up with leftovers, so there’s been an explosion in organizations, like Les Confitures de Dominique in Bordeaux, that turn unwanted fruit and veg into jams, smoothies, chutneys, and soups. In fact, there’s a whole new industry of turning food waste into other food, like Toast Ale in London, which takes the unwanted bread ends that can’t be used for prepackaged sandwiches and turns them into beer.