These days it’s easy to feel powerless. The world is changing so rapidly that it’s hard to know what you can do to make a difference. Well, there is one fairly easy action you can do to benefit the earth — cut down on your food waste.

One tenth of global emissions are caused by food waste, so what you throw in the trash matters. When food is thrown in the trash, it gives off carbon emissions as it decays in the landfill.

Think of events you have frequented, from weddings to picnics to parties, where good food fills the waste bins. Then think of the millions of people in the world who are malnourished. You may not be able to do much to reduce starvation, but you can monitor your own eating habits better to reduce carbon emissions from food waste.

Here are a few suggestions:

• Buy only what you can use before it spoils.
• Freeze leftovers or bread for future use.
• Don’t buy large amounts of food that you can’t use, even if it’s on sale.
• Don’t fill your refrigerator so full that you can’t see what’s there.
• Plan your menus to use what you already have in your refrigerator.
• Don’t take expiration dates too seriously. They may signify the date by which food must be sold, not eaten.

In the United States, as much as 40% of food is wasted because consumers buy too much. In developing countries, the waste is more likely due to farm inefficiencies or poor storage.

Much of food waste happens even before it gets to stores. Food rots in the fields or isn’t stored properly and is wasted during production. If you include the fuel to run the farm machinery, transportation and other factors, the amount of emissions due to food waste increases. Deforestation is sometimes included in the waste because forests are cut down to raise food that may never be eaten. If we include all these factors, food waste accounts for a quarter of global man-made carbon emissions.

According to the United Nations Food and Agriculture Organization, the world throws away about 1.3 billion tons of food, a third of what is produced every year. That waste makes for a larger greenhouse gas footprint than all countries except the United States and China.

Not surprisingly, food waste from wealthy countries like the United States, Canada, Australia and New Zealand is 10 times that of poor regions. According to the FAO, private and public sectors need to invest in better technologies to improve storage techniques. For example, rice storage bags in the Philippines cut losses there by 15%. Training farmers and creating farmer cooperatives lead to more efficient food production.

Since grocery stores and restaurants waste large amounts of food, consumers need to advocate for change. You can urge groceries to sell “misshaped” items for a reduced price so they are not wasted. You can ask the staff at your favorite restaurants what they are doing with their extra food; are they donating it to shelters or Philabundance? A little public pressure may create change.

There are small ways I can reduce waste when I eat out. If my sandwich comes with chips, which I know I won’t eat, I should tell the server in advance not to bring them. I can suggest to the management that the servers ask ahead of time if the customer wants any extras with their meal.

I’ve had some good luck with friendly management around other environmental issues. After plastic straws were automatically given to every customer in a restaurant, I asked that they only be given them on request. (I happened to include a gruesome picture of a turtle with a straw piercing its nose.) Next time I visited, I noticed there was a sign that read, “If you want a straw, please ask for one.”

Each of us can make a difference.