Composting may seem like a humble backyard activity, but it has powerful climate benefits. By diverting organic waste from landfills and turning it into nutrient-rich soil, composting plays a significant role in reducing greenhouse gas emissions—particularly methane, one of the most potent contributors to global warming.
The Problem with Food Waste
When food and other organic materials end up in landfills, they decompose anaerobically—without oxygen—producing excess methane (CH₄), a greenhouse gas much more potent than carbon dioxide (CO₂).
Composting as a Climate Solution
Composting interrupts this cycle by returning organic material to the soil aerobically—with oxygen. This process produces much less methane and results in carbon sequestration as stable organic matter (humus) is added to the soil.
Here’s how composting reduces greenhouse gases:
- Prevents methane emissions by avoiding anaerobic decomposition in landfills.
- Reduces the need for synthetic fertilizers, which are energy-intensive to produce and release nitrous oxide (also a greenhouse gas).
- Enhances soil carbon storage, locking atmospheric carbon into the ground and improving long-term soil health.
Real-World Impact
According to Project Drawdown, composting could significantly reduce emissions between now and 2050, depending on how widely it’s adopted. It would be equivalent to taking hundreds of millions of cars off the road.
How to Start Composting
You don’t need a farm or even a big backyard to get started. Here are some options:
- Backyard compost bin: Ideal for food scraps, garden waste, and paper products. Ideally, use a tumbler version, to increase oxygenation.
- Worm bins (vermicomposting): Great for apartments and indoor use.
- Municipal compost programs: Many cities now offer green bins for curbside pickup.
- Community gardens: These often accept compostable materials and return finished compost to the community.
What You Can (and Can’t) Compost
Compostable:
- Fruit and vegetable scraps
- Coffee grounds and tea bags
- Eggshells (in small quantities)
- Yard waste (leaves, grass clippings)
- Paper towels and newspaper
Avoid:
- Meat and dairy (unless using industrial composting)
- Oily foods
- Plastics, even “biodegradable” ones (unless certified backyard compostable)
- Pet waste
Composting: A Small Act with Big Consequences
If food waste were a country, it would be the third-largest emitter of greenhouse gases after the U.S. and China (UNEP Food Waste Index, 2021). Composting offers a simple, low-cost way to mitigate this. Whether you’re a homeowner, renter, business, or city government, supporting composting helps cut emissions, enrich soil, and build a more sustainable food system.
Key Sources for Further Reading
- EPA – Landfill Methane Outreach Program
- Project Drawdown – Composting
- FAO – Food Wastage Footprint Report
- UNEP – Food Waste Index 2021
- IPCC Sixth Assessment Report – Mitigation of Climate Change
Composting doesn’t require sweeping policy or complex technology—it just takes a little effort and awareness. But when done at scale, it can make a big dent in one of the world’s dirtiest secrets: waste.