THE BASICS OF FOOD WASTE:
Who Generates Methane?
May 14, 2025
As most people in the world are aware, we boycott ‘big oil’ for industrial activities that generate carbon‑dioxide, which contributes to climate change … but, shouldn’t we also boycott individual consumers?
An unexpected question—admittedly. But, here is the point:
Methane gas (CH4) is the second most abundant greenhouse gas, and much of it is generated through food waste. In fact, food waste is one aspect of greenhouse gas contributors that individual people and families can actually control to a great extent. While carbon‑dioxide generation remains the number one problem (on both the industrial‑ and consumer levels), in this account, we will focus on individual consumers’ habits that generate methane—that is: household food waste.
  1. Methane is a much more potent greenhouse gas than carbon‑dioxide
  2. Food waste‑generated methane contributes a significant portion to greenhouse gases
  3. A positive change can happen fairly rapidly if we reduce methane generation because methane has a shorter life than carbon‑dioxide; so the methane already generated will not linger in the air for quite as long (unless we replace it with newly generated methane)
IN A NUTSHELL:
Food thrown away ⟶ rotting process ⟶ generates methane (a highly potent greenhouse gas) which remains in the air ⟵ a seemingly small action of wasting a little bit of food is actually a powerhouse activity of increasing climate change.
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THE ESSENCE
THE DETAILS
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  1. Methane is a greenhouse gas (a fossil fuel): a chemical compound, with the formula of CH4 (one carbon atom + four hydrogen atoms)
  2. Odorless, colorless, and transparent at standard temperature and pressure (i.e. invisible to the human eye) … no wonder we are not aware of it
  3. Methane is about 28‑80 times more potent than carbon‑dioxide (this measure turning out to be 27‑30 times over a 100‑year timespan)*. Its increased potency comes from the fact that it produces more heat per mass unit than other fossil fuels like carbon‑dioxide. Although there is more carbon‑dioxide in the air, methaneis much more powerful
  4. Absorbs infrared radiation, trapping heat in the atmosphere ⟹ therefore, creates greenhouse effect, which causes global warming
  5. ‘Methanogenesis’ is the biological route through which methane is generated, through anaerobic digestion. Occurs in landfills, soils, ruminants (e.g. cows), and the guts of termites
  6. Naturally occurring methane is safely situated below ground and under the seafloor
    BUT:
  7. ‘Atmospheric methane’ (i.e. above the surface and in the atmosphere) generation massively increased mostly due to human activity … among those activities are wasting food (which then rots in landfill), and raising ruminant cattle
  8. An estimated 60% of today’s methane emissions are the result of human activity (e.g. from agriculture, fossil fuels, and decaying organic matter/ food in landfills)
Emissions of greenhouse gases, like methane, warm the Earth by absorbing energy, and slowing the rate at which the energy escapes to space. They act like a blanket insulating the Earth—hence, causing global warming.
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the nitty‑gritty
THE WAYS & THE NUMBERS:

HOW & HOW MUCH METHANE EVERYDAY PEOPLE GENERATE,
and WHY IT MATTERS
  • NATURALLY OCCURRING METHANE
    (Methane clathrates safely situated below ground and under the seafloor)
    • Formed by both geological and biological processes
    • The largest reservoir of methane is under the seafloor in the form of methane clathrates**
    • Methane is also present in permafrost, for example, in the Arctic, in Alaska, and in Canada
  • POPULATION‑BASED HUMAN‑ACTIVITY‑GENERATED METHANE
    (Atmospheric methane, causing/ increasing global warming and climate change)
    • About 60% of methane emissions are a result of human activity
    • Much of the methane generated by the population (i.e. everyday people) is generated by:
      • The decay of organic waste in landfills = thrown-away food rotting in landfills
      • A single cow can produce nearly 100 kg (220 pounds) of methane per year
    • Methane generated by the population at large is
      atmospheric methane
      i.e. not constrained below ground, but is above the surface of the land and the seas, and in the atmosphere; and therefore, creates a warming effect, and contributes to global warming and climate change
    • TThrown‑away food ends up in landfills, emitting methane in the rotting process:
      • Consumers allow food to spoil, then throw the food away (or even before it begins to spoil)
      • Consumers dispose food, based on the sell‑by date even if the food is still safe to eat
      • Farms dispose (or don’t harvest) food that’s not quite up to cosmetic expectations, even if perfectly healthy
      • Restaurants and grocery stores dispose significant amounts of unsold food
      • Food waste is the single largest contributor to municipal landfills, and to the resulting methane emissions from landfills (58%)
      • Globally:
        • About 33% of all food is thrown away
      • United States:
        • 30‑40% of the food supply is wasted = Approximately 133 billion pounds of food per year = About 161 billion US dollars
        • A family of four wastes about $1500 each year on thrown‑away food
      • United Kingdom:
        • About 9.5 million tons of food wasted annually = About 14 billion GBP ⟵ Could feed about 8.4 million people
        • 70% of food waste comes from households
        • Food waste generates about 25 million tons of greenhouse gas per year
        • On average, each person wastes 70 kg of food per year ≅ 140 meals
  • THE SIGNIFICANCE OF METHANE AS IT PERTAINS TO HUMAN LIFE ON EARTH
    • Methane is the second most abundant greenhouse gas (after carbon‑dioxide)
    • Accounts for about 11% of global emissions
    • 28‑80 times more potent than carbon-dioxide—this measure turning out to be 27-30 times over a 100-year timespan*, trapping heat in the atmosphere (having a GWP of 27-30, meaning Global Warming Potential)
    • Lives in the atmosphere for 7‑12 years
    • Methane contributes to climate change ⟹ Climate change also affects food security:
      • Growing and harvesting cycles become less predictable
      • Climate shifts affect timing of planting and harvesting, as well as prices
    • Methane is also a precursor to ozone; and ozone itself is also a greenhouse gas
      • Ozone is linked to public health impacts, such as asthma, weakened lung function, and cardiovascular diseases
    • THE BETTER NEWS: Because it is very powerful, and relatively short‑lived, reducing methane emissions can result in rapid and significant improvement in the climate change phenomenon: limiting near‑term warming, and improving air quality
      • ⟶ next
      • ⟵ back
      • ⟹ consequently
      • ⟸ as said before
    EXPAND ALL COLLAPSE ALL
WHAT CAN YOU DO ABOUT IT?
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In fact, quite a lot. We, as individuals can do quite a lot about reducing methane in the air by adjusting our food buying and food wasting habits. No special tools, no equipment, no expertise, and no money needed. All we have to do is be mindful of how much food we buy, and how much of that we throw away.
BUY JUST ENOUGH/ DON’T THROW FOOD AWAY/ SAVE MONEY
This way, you will prevent the generation of additional methane, and will even save money by not spending it on food that you would otherwise throw away.
Absolutely zero food waste is quite unrealistic in the western world, but the little bit of leftovers you might have can be frozen for later consumption, or be repurposed.
FREEZE OR REPURPOSE LEFTOVERS
TELL YOUR FRIENDS ABOUT IT, SO THEY CAN DO THEIR PART FOR OUR EARTH
The more of us practice mindfulness about food waste, the greater the positive impact. In fact, because methane does its damage quickly and at high impact, reducing methane by wasting less food also results in quick and significant prevention.
By eating less meat (particularly beef and lamb), you lower the demand for animal agriculture, which lowers the methane generated by it.
REDUCE YOUR MEAT CONSUMPTION
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