New York City scrapped door-to-door compost collection.
What does that mean for its methane emissions?


By: Audrey Carleton
Date: December 13, 2020

Justin Wood, director of organizing and strategic research at New York Lawyers for the Public Interest spent his November battling the New York City Department of Parks and Recreation. It’s all an effort to save two drop-off composting sites in the city: One on Long Island City and one in the Lower East Side, both of which he says the department is planning to pull permits on.

It’s Wood’s way of salvaging what little is left of a once robust municipal composting program in the city that included both drop-off sites and curbside pickup in brown bins. The budget for composting – which kicked off as a pilot program in 2013 – was $24.5-million before March, 2020, but was quickly stripped at the start of COVID-19 as a cost-saving measure. Though a small portion of it was resurrected in July, the program’s budget is now a mere $2.8-million, and includes just a handful of drop-off locations, including the two Wood is working to save. Curbside and farmer’s market pickup aren’t expected to return until next summer, at the earliest.

Wood, like many environmental advocates in the city, says composting is an essential part of green urban planning, and a willingness to gut it from high-up is a sign of political failure to recognize the threat of climate change. “It's just very frustrating that there's such a lack of coordination and common commitment to climate change and climate justice from [the city],” Wood says.

Among other environmental benefits, composting diverts food waste from landfills. This reduces emissions of methane – a greenhouse gas known to be 26 times more potent than carbon dioxide – that would normally come from the anaerobic decomposition process (one in which oxygen is not present) that occurs in landfills. Composting, on the other hand, involves the aerobic (or, oxygenated) breakdown of organic matter, in which methane is not produced. Critics like Wood fear that reducing composting could lead to an increase in New York’s methane emissions. The two sites Wood is striving to save are part of a wider concerning trend that could have long-term consequences for the city's contribution to global heating.

An analysis of landfill methane emissions using ten years of data from the Environmental Protection Agency’s Greenhouse Gas Reporting Program (GHGRP) shows this concern is well-founded. I sampled a decade's worth of emissions levels from 17 landfills in 11 counties that implemented municipal composting programs in or after 2010. 71 per cent of landfills saw meaningful declines in methane emissions from the year at which municipal composting was implemented until 2019, with St John Landfill in Portland, Oregon, and Sunset Farms Landfill in Austin, Texas showing the highest drops in emissions (98 and 88 per cent, respectively).

The City of Portland – located in Multnomah County, Oregon, home to the St John Landfill – rolled out citywide food scraps collection to all 147,000 single-family households in 2011 after piloting it the year prior. Residents were provided with sealable kitchen counter composting pails and green roll carts for weekly pickup, which allowed for the collection of items that couldn't normally be composted in backyards, like meat, bones, dairy, grains and pizza delivery boxes. Within just a few years, the program proved a worthwhile investment.

“Since the food scraps collection program started three years ago, Portland residents have reduced garbage going to landfill by 36 per cent," Arianne Sperry, a manager in the city’s Solid Waste & Recycling office told BioCycle in 2015. "No other single program change could make such a significant difference.”

The City of Austin, Texas rolled out its own curbside program for 7,900 households the following year, and has steadily increased its reached in the years since. As of 2019, the program served 148,000 Austin households in an effort to achieve a citywide Zero Waste goal of diverting 90 per cent of its landfills by 2040. The city also launched a pay-as-you-throw plan – in which residents are charged for solid waste services depending on their volume of disposal – in the early 1990s, becoming one of the first major cities in the country to do so.

According to data provided by the city government, Austin's approach is working. As of 2015, residential food scrap and hazardous household waste collection programs were responsible for the diversion of 40 per cent of the city's waste from landfills.

But not all progress is linear; and not all composting programs see the same results. A site-by-site analysis of eight landfills that implemented composting on or before 2011 shows variations in methane emissions trajectories. While the Lexington/Fayetteville landfill – which serves Lexington, Kentucky residents, who began composting curbside in 2011 – has seen steady declines in emissions over the last ten years, landfills like Bexar County's Tessman Road, located near San Antonio, have seen emissions increases. The city of San Antonio piloted residential food scrap collection in 2011, on a $3-per-month subscription basis, which has since expanded to serve a larger number of residents. The county is also home to two other landfills: Covel Gardens and Nelson Gardens, both of which saw net decreases in methane emissions between 2010 and 2019, a sign of progress that could make up for a lack thereof at Tessman Road.

Despite fluctuations, composting is, generally speaking, a net good in a time when global methane emissions are increasing and the UN Intergovernmental Panel on Climate Change (IPCC) estimates that there is only a decade left until climate change becomes irreversible. On average, methane emissions at the 18 landfills where composting programs were enacted declined by nearly 7 per cent in the years since said programs were piloted – with some programs seeing methane emissions reductions of nearly 100 per cent in 10 years. By comparison, the average U.S. landfill saw methane increases by 1.88 per cent in the last ten years, an analysis of 1,093 U.S. landfills represented in the GHGRP shows.

"Getting rid of methane is a great way to to lessen the impact of climate change very quickly," said Dr. Sally Brown, research professor in the University of Washington department of Environmental and Forest Sciences.

Compared to other greenhouse gases, like carbon dioxide, methane is "short-lived in the atmosphere," Brown says. But its potency, she notes, makes it particularly dangerous in the short-term. "On a 100-year timeframe, it's about 23 times as potent as CO2."