It’s the secret shame of many Americans: The half-forgotten (or wholly forgotten) perishables in your refrigerator and pantry that have been overlooked, uneaten, and are now turning pretty colours or else giving off the fragrance of a corpse.

Those of us who feel pangs of guilt and upset over wasted food are sadly in good company: Some estimates reveal that Americans waste as much as 60 million tonnes of food a year (for various reasons, some simply because of extremely high standards set by American stores)! Given the plight of world hunger, this fact is shameful enough, but what many of us may not realise is that wasted food also has a harmful effect on the environment.

So that we might be better stewards of the earth we have been given, here are five biggest ways wasted food hurts the environment—and five ways we can combat this problem and make it better for millions of people worldwide.

1. It wastes water

Water is essential to life, and it’s no surprise it’s essential to food production as well. Whether from irrigation, spraying, pouring, or some other means, water is essential to the growing of agriculture, not to mention the feeding of animals that give us our meat, fish, and dairy.

But in throwing out millions of tons of food, we also waste uncounted millions of gallons of water that was used to plant, grow, sustain, or otherwise produce it.

Fruit and vegetables are among the most water-laden food products, simply because they contain more water. (For example, one bag of apples is about 81% water!) But meat products are the heaviest water users, simply because the animals drink a lot of water—and more importantly, because so much water is needed for the grain that becomes their feed! It takes about 8 to 10 times more water to produce meat than grain.

All told, if the 1.3 billion tons of food wasted worldwide each year is accurate, most estimates place the water “in” that amount to be 45 trillion gallons—or 24 percent of all water used for agriculture. And remember that 70% of the world’s freshwater is used for agriculture.

2. It releases Methane

When food is thrown out, it eventually makes its way to landfills (which can themselves be a problem for the environment). As that food begins to decompose or rot, it releases methane gas.

Methane, of course, is a greenhouse gas, which many scientists believe adversely affects the earth’s climate and temperature (i.e., climate change/global warming). Here’s why the millions of tons of food wasting in American landfills should concern you:

• Methane is more effective at trapping heat in the atmosphere than CO₂—about 25 times more effective.
• Methane accounts for about twenty percent of greenhouse gas emissions.
• Much methane, as well as other adversely-affective gases, has already been released in the production process. The wasted food is now adding to that.

Less wasted food means we release less methane gas, which is way better for the environment.

3. It wastes oil

This is another “production” side of the waste epidemic. Here’s what I mean:

• Oil, diesel, and fossil fuels are required to grow, transport, store, and cook food. Think of the harvesting machinery that has to be powered, the vehicles taking the food from the farm to the warehouse to the store, the further machinery that is used to sort, clean, package, or otherwise prepare the food just so it can be bought. Much of this machinery requires massive amounts of oil, diesel, and other fuels to function.
• To waste millions of tons (in America) or billions (worldwide) each year also means that all of the oil and fuel that has gone into the production of said food is wasted.
• Moreover, using that fuel in the first place can release harmful amounts of greenhouse gases into the environment, combined with the other harmful amounts released from the decomposing food already in landfills, and all of the future decomposing food that will yet be wasted.

Wasting fuel and oil both at the front (production) and the back (decomposition) end by not eating the food we purchase has a hidden but costly impact on the environment.

4. It wastes land

Land use as regards food falls into two main categories: The land used for production, specifically the crops and grassland used in the actual growing (or raising, in the case of livestock), and the land used for retaining food that has been thrown out.

Unsurprisingly, the irresponsible use of food products has an adverse impact on the physical land itself.

If you recall your high school science classes, you may have heard the terms arable land and non-arable land. This simply means land that can grow crops (arable), or land that cannot (non-arable). This factor is important for evaluating how food waste affects land.

Most of the land needed to produce milk and meat is non-arable (think meadows, fields, etc.). It’s perfect for livestock, but terrible for growing crops. But most of the food wasted worldwide, regardless of the type of land, is meat.

about 900 million hectares of non-arable land are used in the production of the world’s meat products. Moreover, when you count all of the land needed to produce other foods, like the millions of pounds of fruits and vegetables we waste each year, the use of land skyrockets.

This would not be a problem in itself. However, the problem lies in both the waste of the food (so the land is being used for an ultimately pointless purpose) and the fact that land, if not cared for, loses its ability to yield over time—called degradation. Eventually produces far less than can sustain the people living in the region.

5. It harms biodiversity

“Biodiversity” is simply a fancy word for the diversity of life in an ecosystem or environment—the full spectrum of life across different species and kinds of organisms. This is a hidden but real cost of food waste: it decimates biodiversity in a number of ways:

• Deforestation, especially in tropical areas, destroys natural flora and fauna (sometimes to the point of extinction), in the name of creating more land for food production.
• To increase production of livestock, natural land is turned into pastures, which besides the aforementioned deforestation also impacts biodiversity by the increase of livestock; the more livestock graze and range on an area, the less natural and diverse the area becomes.
• Marine fisheries are a large culprit in the decimation of marine ecosystems and natural habitats, often resulting in “overexploited” areas or stocks (indeed, the ten most caught species of fish all have been labelled as “overexploited”). Fish are caught with little thought given to how the rapid depletion of population will impact their environments. These fish then get thrown out by the consumer, or rejected by stores for not meeting certain standards, or rot in the truck because of lack of modern refrigeration (in developing nations).

Other ways food production may impact biodiversity have either not been studied or the links between the depletion and the production are not yet clear. Still, it’s one thing to impact the land to create food that is then scrupulously used. It is another thing entirely to impact the land so drastically (sometimes unnecessarily) for food that will be largely wasted.