Food waste is a growing climate threat - can composting help?

When you toss food waste into the trash, it might seem like no big deal. After all, it’s organic – it’ll break down eventually, right?

But what actually happens to that waste after it’s hauled away is a much bigger issue than most people realize. And it’s not just about overcrowded landfills – it’s about methane.

Food waste buried in a landfill doesn’t simply rot and disappear. It releases methane, a greenhouse gas that’s 80 to 85 times more powerful than carbon dioxide over a 20-year period.

This makes food waste a serious player in climate change – not because of how much we toss, but because of where it ends up and how it breaks down.

Landfills turn food waste into methane

Here’s the issue: landfills aren’t built to help food break down cleanly. When food waste ends up buried under other trash, it quickly uses up the oxygen in its immediate surroundings.

At first, some decomposition happens with oxygen, which releases carbon dioxide – still a greenhouse gas, but not nearly as potent.

But once the oxygen’s gone, the process switches. Now you’ve got anaerobic decomposition, which happens without oxygen. This is where methane starts building up.

And unlike compost piles, which stay exposed to air and rely on oxygen, landfills are packed tight. That makes them perfect methane factories.

Composting transforms food waste

Composting does the exact opposite. It keeps oxygen in the mix throughout the process. That means no methane. Plus, it turns food scraps into something useful: a natural fertilizer that can go back into farms and gardens.

Some cities, especially in recent years, have started composting programs to cut down on landfill methane. But how effective are these programs? Do they really work?

One recent study examined how composting plays out in real life, based on actual data. The study concentrated on places such as Austin, Texas, where there are programs set up to allow people to compost at home.

On average, the program reduced organic waste output by roughly 2.3 pounds per household per week. That’s a good start, but it’s only about 30% of what a typical American household discards a week.

Composting requires individual effort

There’s also the question of participation. Unlike cities such as San Francisco, many places don’t enforce composting. That means it’s optional – and a lot of people skip it.

Jackson Somers is an assistant professor of agricultural and resource economics in the College of Agriculture, Health and Natural Resources (CAHNR).

“As individuals, we produce a lot of food waste, and it’s something we should be cognizant of. From there, you should compost if you want to compost,” said Somers.

“I think, inherently, we don’t want to be wasteful. But for some people it’s just a high burden of effort.”

Composting isn’t cheap – yet

Even with some success, the economics are tricky. According to Somers’ analysis, it currently costs about $478 to avoid emitting one ton of CO2 through composting programs.

By comparison, the “social cost of carbon” – a number economists use to estimate the damage caused by each ton of carbon emissions – is set at $51.

That means composting, at least in small-scale residential programs with low participation, isn’t cheap when measured in dollars.

“With current programs, given the infrastructure we have – these programs are really expensive for the savings we see,” Somers said. But that doesn’t make composting a lost cause.

Short-term cost, long-term gain

The cost of building new landfills is rising fast. Once current landfills are full, finding and building new ones will be a big financial burden for many cities. So building composting infrastructure now might save money down the road.

Also, the social cost of carbon isn’t fixed. As scientists understand more about climate change, the estimated damage from each ton of carbon goes up. That means composting could become more cost-effective over time – even if the upfront price is high.

“As we learn more about our impact, composting programs may become cheaper from an environmental sense,” Somers said.

The study focused on households, but Somers pointed out that restaurants, grocery stores, and other businesses throw away massive amounts of organic waste. That’s where composting could really move the needle.

“That’s where I think you can see real savings. I think that’s something we should consider more than we do,” said Somers.

Unexpected benefits of composting

Composting might also bring unexpected benefits. Large cities with lots of exposed food waste deal with more mess and public health concerns. Composting can help reduce that and keep neighborhoods cleaner.

“Keeping rats and other pests out of neighborhoods certainly goes into the calculus too,” Somers said.

“How many people get sick from rats? How much do we dislike seeing rats running around on the streets? It’s important to factor in other impacts, not just environmental.”

No universal fix for food waste

Different communities need different solutions. Demographics, geography, and even local habits all shape what works best.

In some Connecticut cities, compost bins are picked up curbside. In others, residents drop off food scraps at centralized locations.

“A one-size-fits-all solution is not the answer,” Somers said. “The solution in northwestern Connecticut is very different from the solution in Stamford or Hartford – and the solutions for Stamford and Hartford are also going to be different because demographically they’re quite different.”

The full study was published in the journal Journal of Environmental Economics and Management.

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