Methane Emissions from Trash Fuel Climate Warming

Did you know that your trash that ends up on a landfill not only has an environmental impact but also has a huge impact on climate, and not in a good way. Everything we use in our day-to-day lives typically ends up in landfills once it has served its useful life. The final resting place for everything from plastic bags, milk cartons, cardboard boxes, and other packaging materials, to torn clothes, kids broken toys, or your pooch's chewed up old frisbee, to food scraps and even old refrigerators and other appliances, is typically the local landfill. Consequently, the stream of garbage entering landfill sites across the country is endless. So are methane emissions from landfills.

A typical scene includes bulldozers busily cover the garbage with dirt to discourage flies, rats, and feral animals from scavenging on the easy pickings, while seagulls and other birds hover eagerly about. But once the garbage is buried under a pile of dirt it does not miraculously disappear. It may be out of sight, but it can still have a huge impact on the environment.

Landfills are one of the largest sources of methane emissions a potent greenhouse gas that contributes significantly to climate warming.

Methane is emitted from landfills when organic waste material such a paper, wood, and food scraps decompose in an anaerobic environment. The anaerobic bacteria that break down these materials produce methane during the decomposition process. This methane typically escapes into the atmosphere, unless it is captured or flared.

The Global Methane Assessment published by the Climate and Clean Air Coalition in collaboration with the United Nations Environmental Program in May 2021 concludes that implementing measures to reduce methane emissions offers the best and fastest solution to slowing climate warming.

However, there are several challenges to reducing methane emissions, starting with getting a clearer understanding of just how much methane is escaping from landfills. Just how much methane leaves landfills? Well, it depends who you ask. Landfill operators tend to think methane emissions from landfills are overestimated, while researchers and methane experts believe that not only are they are significantly underestimated, they are also underregulated.

Susan Thorneloe, a senior chemical engineer at the US Environmental Protection Agency (EPA) who has worked on the EPA's methane estimation methods for more than 30 years, told NPR that the EPA has been understating methane emissions from landfills by a factor of two. Thorneloe believes that the methods currently used by the EPA to estimate methane emissions from landfills are outdated and flawed.

This view is supported by Environmental Integrity Project attorney, Ryan Maher, who is the author of a recently published report that details greenhouse gas emissions from Maryland's landfills, which found methane emissions from Maryland's landfills were four times higher than state estimates. "We're basing our emissions estimates on models rather than direct measurement," said Maher, adding that we do have the capacity to measure these emissions directly, we just haven't been doing so.

Since methane is relatively short-lived in the atmosphere compared to carbon dioxide, which can linger in the atmosphere for more than a century, reducing methane emissions could help to reduce climate change almost immediately. It is therefore important that we gain a more accurate assessment of methane emissions, so we know what areas to target and can assess progress. Landfills, together with livestock and oil and gas production, are one of the top three anthropogenic sources of methane emissions, and the United States is the third-largest emitter of methane globally.

According to the UN report, drastically cutting global methane emissions within the next ten years could help to prevent roughly 0.3 degrees Celsius of additional atmospheric warming by 2040. This in turn would help to prevent average global temperatures from increasing above 1.5 degrees Celsius compared to preindustrial temperatures and help to avoid more severe climate change impacts, in accordance with goals set by the Paris climate accord.

Cutting methane emissions is one way to rapidly reduce atmospheric warming. Targeting methane emissions from landfills presents an ideal opportunity to do that, as the captured gas can also be used as a source of clean energy. So not only are you preventing a potent greenhouse gas from escaping into the atmosphere, but you also now have access to an energy source that burns cleaner than fossil fuels.

Featured Image Credit: UN Photo/Evan Schneider (CC BY-NC-NC 2.0)