Composting is an Easy Way to Cut Landfill Methane Pollution

But the benefits extend well beyond that

Hiya!

When it comes to global warming, carbon dioxide (CO2) gets most of our attention since there’s so much of it, and it’s the primary greenhouse gas our societal setup emits. Meanwhile, methane (CH4) is well known but less discussed.

Despite being the second most common greenhouse gas we create, methane is generally deemed not as threatening as carbon dioxide because it has a shorter lifespan in our atmosphere. But we shouldn’t underestimate methane’s threat.

Luckily for us, researchers found a simple solution, both for individuals and culturally, that could make a big difference in methane levels.

Carbon Dioxide vs. Methane

Before we get to the research, let’s discuss some differences between carbon dioxide and methane.

CO₂

In 2021, carbon dioxide accounted for 79 percent of all United States greenhouse gas emissions caused by human activities, especially from using fossil fuels for energy and transportation.

The total amount of carbon dioxide in Earth’s atmosphere seems less daunting at 0.042 percent in 2022 — but that’s still nearly a 50 percent increase since pre-industrial times. Also, the number may seem tiny, but climate models predict that increasing atmospheric CO2 levels from .04 percent to .05 percent is enough to raise global temperatures well beyond the international goal set in 2015 of a 1.5° Celsius limit.

A rise to 0.10 percent, three times pre-industrial levels, would bring about “catastrophic warming of several degrees Celsius,” Paulo Ceppi, a senior lecturer in climate science at Imperial College London, told Reuters.

Carbon dioxide also has a long lifespan and is known to linger in the atmosphere for between 300 to 1,000 years or more.

CH₄

Comparatively, methane accounted for a measly 12 percent of all U.S. greenhouse gas emissions related to human activities in 2021 — which mostly came from agriculture, energy and industry, land use, waste management, and landfills.

Compared to CO2’s intimidating longevity, methane hangs around the atmosphere for a fraction of the time — only a decade or so. Considering these things, CH4 seems far less threatening and crucial to address in our attempts to stabilize global warming.

But longevity matters less than what the gases accomplish during the time they spend in our atmosphere, however long that is. And methane happens to be 28 times more effective than carbon dioxide at trapping heat on a 100-year timescale and is responsible for about a third of current global warming.

Daniel Jacob, the Vasco McCoy Family Professor of Atmospheric Chemistry and Environmental Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), explains:

“What that means is that methane is responsible more for near-term climate change, but it also means that acting on methane can give us a short-term climate response. So, if we are trying to address climate change over the next decade or two, methane is a very powerful lever.”

Agriculture, oil, and fossil fuel use are the primary contributors of methane, but it’s challenging to imagine us limiting any of those resources (even though we should) anytime soon. However, a significant amount of methane comes from landfills, and that is something we can address.

Landfills

We all know landfills are a problem… many problems, in fact. One of which is being the third-largest source of global methane emissions caused by human activity. Part of the reason for such high rates is because food waste is the most common landfill item. That shouldn’t be too surprising since about a third of all food in the United States goes uneaten. (That’s about 130 billion meals a year.) The United States Environmental Protection Agency (EPA) states:

“Due to its quick decay rate, food waste in landfills is contributing to more methane emissions than any other landfilled materials.” And that “an estimated 58 percent of the fugitive methane emissions (i.e., those released to the atmosphere) from municipal solid waste landfills are from landfilled food waste.”

See, for better or worse, bacteria find our wasted food delicious. They gorge upon our discarded heaps of organic matter, burping methane as they go — a process called anaerobic decomposition.

Unfortunately, our global waste management systems rely on landfills. And while many people know on some level that landfills are a problem, there’s a sort of “out of sight, out of mind” aspect as well. Not to mention all the things made to be disposable yet are created out of materials designed to last for centuries. Sigh.

We can’t change everything, but research shows composting is one small change that can yield significant and long-term positive results.

The Study

In May 2023, nature’s journal, Scientific Reports, published a study by researchers at the University of California Berkeley who analyzed the impact composting has in mitigating the consequences of climate change. Whendee Silver, an ecologist at UC Berkeley, and her associates discovered composting is a valuable and easy tool to significantly lower methane emissions.

For the study, the researchers measured the carbon dioxide, methane, and nitrous oxide emission levels — our top three greenhouse gases — at a commercial compost facility in California throughout the composting process.

They aren’t the first to study and compare landfill vs. compost emissions, but Silver told Grist their study differs because they used a new method that “allowed us to figure out exactly when and where and under what conditions the greenhouse gas emissions were occurring.”

More specifically, according to the study, they used a “non-invasive micrometeorological mass balance approach,” and didn’t adjust the compost conditions while taking measurements.

Ultimately, they found that composting food scraps results in 38 to 84 percent fewer greenhouse gas emissions than tossing them in landfills. Better estimates of greenhouse gas pollution caused by landfills will help experts like Silver narrow down the exact impact. Still, their findings are impressive.

The researchers note that “fine-tuning” the composing process could even further lower emissions. Unlike landfills, water is added to compost heaps, and they are turned more frequently, introducing air into decomposing waste and decreasing the methane produced by bacteria.

Doing things like turning compost heaps more frequently, adding water more often but in smaller quantities, and installing new tools such as aeration tubes underneath compost piles could further lower methane emissions.

Composting

Slashing methane emissions is a fantastic perk of composing, but it’s not nearly the only one. You’ve probably heard that compost is an excellent fertilizer that enrichens soil with plant nutrients, suppresses plant disease, helps soil stay moist, and reduces erosion.

Composting is fantastic for the environment and plants and could decrease or maybe even totally eliminate our need for commercial fertilizer, which is responsible for more damage than I have the stomach to get into right now. Not only are many chemical fertilizers terrible for us and the environment, but they also contribute significant greenhouse gases, primarily nitrogen levels, which, by the way, have jumped 30 percent over the last forty years.

Beyond reducing our reliance on commercial toxins, research shows that applying a layer of compost to farmland is crucial for storing carbon in the soil. Other research suggests lying compost over an agricultural field about the size of an acre can capture enough carbon to offset 75 percent of one car’s annual emissions.

A growing number of cities, including Boston, Pittsburgh, and Jacksonville, are joining San Francisco, Portland, Oregon, and Seattle in creating mandatory composting programs that include things like providing compost bins for each household and curbside compost pickups — just like garage and recycling — to prevent food scraps from entering landfills.

Though requirements and programs vary, several states are jumping on board, including California, Connecticut, Maryland, Massachusetts, New Jersey, New York, Rhode Island, Vermont, and Washington.

Perspective Shift

Composting is one of those super simple solutions that seem like a no-brainer. There’s little to no downside but several substantial benefits — and it’s so easy. It would be fantastic if more cities, states, and even entire countries encouraged residents to compost and provided them with the means to do so.

But we can also compost ourselves at home to use in our personal or community gardens. Or maybe you’re a plant lover with an apartment of house plants and no yard — that’s okay because you don’t need a yard to compost. Heck, you could even sell it.

Composting is one small solution that can make a big difference and inspire further positive change. Maybe someday, all packaging will be compostable. Perhaps our composting sites will one day outnumber our landfills. I mean, who knows? But it sure is fun to think about.

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Photo by Nareeta Martin on Unsplash