Switching to compact fluorescent bulbs. Biking to work. These are basic tactics in the battle against global warming. But what about dinner? Food is often overlooked in the race to cut energy consumption and greenhouse-gas emissions. And yet, switching from a diet high in animal products — particularly beef — to a diet of mostly vegetables, grain, and poultry is tantamount to trading in a gas-guzzling Yukon XL for a hybrid Prius.

A meal's carbon footprint all starts with how its ingredients are produced. Before it even hits the road, the food you consume requires vast amounts of fossil fuel to grow and process: Fertilizers, pesticides, farm machinery, processing, and packaging all eat up their share. In fact, transportation accounts for only 11 percent of foods' carbon footprint, while the production phase makes up 83 percent. And although all foods require energy to be produced, some require much more than others: Producing a single cheeseburger sends a hefty 10.7 pounds of carbon dioxide (CO2) into the atmosphere. A family of four that cuts out burgers once a week saves the planet 2,225 pounds of carbon emissions a year — the equivalent of unplugging your fridge for 365 days. Unrefined plant-based foods, on the other hand, require much less energy. A veggie stir-fry of carrots, broccoli, and peppers causes only 1.5 pounds of CO2 emissions.