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Apr 247 min read

Rotten: The climate impact of the food we waste

Stop Food Waste Day is April 24, 2024



Photo by Alexas_Fotos on Unsplash


Imagine shopping for groceries and then dumping a third of your purchased food items into a trash bin each time you exit the store. Preposterous? That scenario is on par with how much food American households waste each year. On average, Americans waste 38% of their food, throwing out about one pound per day per person, adding up to over $1800 a year for a family of four.


Two-thirds of household food waste is from food that goes bad before it's used. Bread, dairy, fruits, vegetables, and eggs are the most frequently wasted foods, with potatoes being the most wasted vegetable. On Thanksgiving, it's turkey: We give thanks for our food and then throw out one-third of the bird.


Food has become the single most predominant waste material, accounting for 25% of landfilled material and 22% of incinerated material. Our habits helped shape this reality, since the largest contribution comes from our homes.


Wasted resources and a mess of methane

It's not just the food itself that's wasted but all the resources used to produce it. Take water, for example: Agriculture accounts for 80% of all water consumed, and 25% of the world’s fresh water supply is used to grow wasted food. Other wasted resources include land, pesticides, fertilizers, labor, fossil fuels, and energy. Combined, these wasted resources have a carbon footprint of about 3.3 billion tons of carbon dioxide, equal to the emissions of 37 million cars or more than 42 coal-fired power plants—and that's before factoring in the greenhouse gas emissions that food waste generates in landfills.


When food or other organic matter ends up in a landfill, it generates methane, a greenhouse gas that is responsible for one-third of the current rise in global temperature, trapping 80 times more heat than carbon dioxide during its 7-12 years in the atmosphere. Add food waste to a landfill and you end up with a methane factory: The tightly compacted waste has little room for oxygen to circulate, resulting in anaerobic (without oxygen) decomposition where bacteria eat the organic matter and burp out methane. All those burps add up:

  • Food waste produces 11% of global greenhouse emissions.

  • Landfills produce one-third of all methane emissions in the US, and 58% of these emissions come from food waste.

These numbers are likely significantly underestimated, according to a recent study from March 2024, led by the non-profit Carbon Mapper alongside researchers from NASA Jet Propulsion Laboratory, Arizona State University, University of Arizona, Scientific Aviation, and the US Environmental Protection Agency (EPA). It's the largest study of its kind to date, using advanced airborne imaging spectrometers to gather data over six years. Researchers studied 20% of open landfills in the US and found methane emissions to be 1.4 times higher than the those reported to the EPA by landfill operators. About 240 sites were studied, and over half had significant methane emissions. Of those, 60% had emissions that persisted for months or years. More than 850 individual methane plumes had emission rates of 100kg or more per hour, the rate set by the EPA to classify "super-emitters" in the oil and gas sector.


Opportunity in a broken food system

Food waste is pivotal to the Paris Agreement target to limit the global temperature to 1.5 degrees above pre-industrial levels. Even if we eliminated fossil fuel emissions, we couldn't reach that target without reducing the emissions associated with our broken food system. Addressing the food system was identified as the leading high-impact solution by Project DrawDown, taking precedence over electric cars, solar power, and plant-based diets.


The opportunity is huge: Eliminating global food waste would save 4.8 million tons of carbon dioxide a year, equivalent to taking one in four cars off the road. Composting alone has the potential to reduce 84% of landfill emissions. Composting further reduces greenhouse gases by increasing carbon sequestration in soil. By some estimates, adding compost to an acre of land can offset 75% of a car's yearly emissions. Other benefits include improved soil quality, increased crop yields and drought resistance, and reduced need for inorganic fertilizers, which can contaminate ground water. Bodies of water would also be protected from nitrogen pollution, a by-product of landfilled food waste that causes algae blooms and dead zones.


Meaningful change likely won't occur without increased infrastructure and government support, although ironically, fixing the system comes down to two key activities that we have direct control over:

  1. Waste less food.

  2. Keep food waste out of landfills and compost it instead.



In 2015, the Department of Agriculture and the EPA announced a goal of cutting food waste in half by 2030, and since then the amount has increased by 6%. In 2021, the US Methane Emissions Reduction Plan set a target to reduce landfill methane emissions by 70% through a voluntary outreach program. The program funds private-sector companies that provide composting and organic waste collection, food waste task forces that provide composting education and infrastructure, and measures to reduce food waste in food-related businesses and schools.


In the US, only about 5% of food waste is composted and as of 2023, only nine states have passed legislation restricting the amount of food waste that ends up in landfills, and these include California, Connecticut, Massachusetts, New Hampshire, New Jersey, New York, Oregon, Vermont, and Washington. (Note that restrict doesn't necessarily mean ban.) In some cases, restrictions apply only to businesses that meet certain criteria or to specific cities or counties. Other states have implemented voluntary measures to varying effects. For example, Chicago has a city-wide composting program with six free drop-off locations. Not ideal for people who don't have the time and transport to take advantage of it.


A hungry and growing population

America wastes more food than any other country, despite 1 in 6 Americans being food insecure, and it contributes 80 million tons of wasted food each year to the worldwide total of 1.3 billion tons. The world has nearly a billion hungry people, and wasted food from the US, UK, and Europe alone is enough to feed them four times over. By 2050, the world's population is expected to reach 9 billion. To feed that many people, output based on today's food system will need to increase by 70%.


To sustainably feed our growing population, a more efficient food system is needed to offset increased deforestation, biodiversity loss, greenhouse gas emissions, water pollution, and water scarcity. Farmers and manufacturers also need to address their own contributions to food waste, most of which happens during production and another 12% when produce is too ugly, too big, or too small. More perfectly good food is tossed when it's thought to be too old, thanks to confusing expiration labels. A UK study found that standardized expiration dates could reduce household food waste by up to 20%.


Actions you can take

Stop Food Waste Day comes once a year to raise awareness and inspire changes that we apply to our daily lives. Remember those burping bacteria? They're proof that little actions add up to massive outcomes. The same rules apply to us, and you can make a difference by adopting the little actions below to prevent food waste. In the meantime, I'm going to salvage an apple and a pear that are sitting on my kitchen counter before they meet their expiration dates.


  • Create a weekly meal plan and base your grocery list on it. A former coworker shared this tip with me, and while it took some getting used to, I soon realized the benefits: Not only did I save money by shopping more intentionally, but I ended up with less food waste, and I didn’t have to figure out what to make for dinner when I was tired and cranky at the end of the workday. I also made better use of ingredients I had on hand.

  • Keep track of food you throw away: If you consistently throw out an item, buy less of it or find other ways to use it.

  • Understand food expiration dates.

  • Organize your refrigerator and pantry so that foods that will expire soonest are in front, easy to see, and easy to access.

  • Eat your leftovers and freeze what you can't eat right away.

  • Learn how to properly store food so it lasts longer.

  • Prevent freezer burn: Set the freezer to 0 degrees Fahrenheit and keep it moderately full—not packed, not sparse—so that it's better able to maintain its temperature. Remove as much air as possible when storing food. Meat and poultry can be stored in their original packaging, and reusable silicone storage bags work well for almost anything. When using solid containers, like glass jars, be sure to leave room to accommodate expansion.

  • Eat the ugly stuff and adopt scrap cooking. Find inspiration from potato peels, carrot tops, stale bread, and apple cores. Nutrient-rich banana peels can be turned into a flour that is surprisingly good for baking, used in Nigella Lawson’s cauliflower and banana peel curry, or transformed into vegan “bacon” or “pulled pork.” My personal go-to for scraps is to keep a silicone bag or large glass jar in the freezer for collecting vegetable trimmings (plus vegetables past their prime), chicken bones, and fish bones. Once I have enough, I simmer the scraps to make stock. I save money and don’t add Tetra Paks to the landfill.

  • Learn how to propagate vegetables like green onions, celery, and lettuces.

  • Grow your own herbs so you can harvest only what you need.

  • Support food rescue efforts: Find restaurants and bakeries that are about to close and purchase their excess food at a reduced cost, donate to a food bank, or connect with a food rescue program. These apps make it easy to fight food waste.

  • Bring your own containers when dining out or getting takeout (and don't forget to eat the leftovers).

  • Start composting! Here’s a beginner's guide to get you started.


The list above originally appeared in Resolve to be less trashy in 2024 and was updated for this article.


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