One of the biggest contributors to global warming is the food-supply system, from the fertilizer and gas used to cultivate farms to transportation and storage to what we throw away at the end of a meal. We won’t stop climate change through individual action alone, but together, we can make a real difference.

Here are four simple things we can do in changing the way we consume:

1. Eat less meat and dairy, especially beef and lamb. Livestock are by far the biggest producers of greenhouse gases in the global food system. In the U.S., most livestock-related emissions come from the animals’ digestive systems and from the fertilizer used to grow their feed. If an American family of four ate no meat or cheese one day a week, it would be like taking a car off the road for five weeks a year, according to estimates by the Environmental Working Group. If we all did it, it would be like not driving 91 billion miles.

2. Waste less food. Farmers have to grow far more food than we actually need because 40 percent of what they produce gets thrown away. That comes at a huge cost in greenhouse gases. Food waste in landfills also produces methane, which is 21 times more powerful than carbon dioxide in trapping heat in the atmosphere. Try not to buy more than you can eat, and make creative use of your leftovers. Be aware of portion size and of falling into the trap of eating food just because it’s there. Buy food that’s less than perfect so the store won’t toss it out. It also helps if you compost your kitchen scraps.

3. Use less energy. Stores and restaurants generally don’t provide information about the energy used to produce, process and bring us our food, but we can make some guesses. Highly perishable, out-of-season produce often comes by airplane, one of the most fuel-hogging vehicles. Processed foods take a lot of energy to produce. And the energy we use to transport, store and prepare food also contributes a surprisingly large share of food’s greenhouse gas emissions. Make fewer car trips to the store -- can you bike or walk? -- and consider buying Energy Star appliances. And cover your pots when you cook.

4. Support sustainable food systems. Pound-for-pound, sustainably and locally produced foods may not always be the lowest emitters of greenhouse gases. But climate-friendly eating also means doing all we can to shore up our food system so it can withstand what climate change has in store for us. The best way to do that is by shifting toward more sustainable production methods and more efficient local and regional distribution systems. Buying from responsible producers in your area -- and the restaurants and stores to which they sell -- helps strengthen that system.

There’s much more we can do, from examining our other food choices beyond meat and dairy to planning ahead, slowing down and appreciating the foods in front of us. And after we’re done voting with our forks, we can vote with our ballots, emails, phones and wallets. Demand that government and businesses step up and take action on greenhouse gases. If they hear from us enough, they’ll do it -- and we will have done our part to assure that we can enjoy our meals tomorrow as much as we enjoy them today.