Wasting food has been called the “world’s dumbest environmental problem.” Every year, the average family of four in the U.S. tosses roughly $2,000 in food; 30 to 40 percent of food produced in this country ends up discarded.

At dinner, our parents urged us to finish everything on our plates. Beyond the moral and economic reasons to do so, it turns out there’s a significant environmental one, too. When food winds up in landfills it produces methane, a greenhouse gas that is far more potent than the poster child of greenhouse gases, carbon dioxide, which primarily comes from fossil fuel use.

In fact, if food waste were a country, it would be the world’s third-largest emitter of greenhouse gases, behind China and the United States. Few people realize that when they shove some grapes into the bottom drawer of their refrigerator and forget about them, they are contributing to climate change.