Divert Biodegradable Waste From Landfills to Cut Climate-Warming Methane Emissions

Landfills are one of the largest drivers of methane pollution in the U.S. and globally, but they don’t have to be. If we were to invest in infrastructure to divert all food and other organic waste from landfills, we could slash landfill methane emissions entirely.

I am one of 35 scientists, including four from Columbia, calling on U.S. climate leaders to push for policies aimed at diverting the nearly 300 million tons of organic waste that the United States sends to landfills each year. As U.N. climate talks got underway last week, the United States and the European Union are leading a Global Methane Pledge to encourage countries to cut emissions by at least 30 percent by 2030. The U.S. could be well on its way to reaching this 30 percent goal merely by changing how we deal with biodegradable waste.

Carbon dioxide has dominated the news for decades, and now methane is having its moment. It’s about time. Methane is 80 times more potent than carbon dioxide over a 20-year period, according to the Intergovernmental Panel on Climate Change, and has contributed to nearly a third of the warming since the pre-industrial era. But unlike carbon dioxide, which lingers in the air for centuries, methane breaks down in about a decade. That’s an enormous incentive to act. If we cut methane emissions now, we will see the benefits almost immediately. It’s no surprise that a U.N. report in May called methane, “the strongest lever we have to slow climate change over the next 25 years.”

Cutting carbon emissions requires that we rebuild virtually our entire energy infrastructure globally. Lowering methane, by contrast, can be achieved with simple policies at the local level. Landfills represent the third largest source of methane pollution, after fossil fuel production and agriculture, and new studies suggest that landfill emissions may be three times as high as U.S. Environmental Protection Agency estimates. That means that investing in infrastructure to reduce or eliminate landfill methane emissions will pay huge dividends, and fast. 

It’s also relatively easy. Technologies for diverting post-recycling waste from landfills are commercially available, and include everything from thermal processing plants to composting programs launched by cities from Cambridge, Mass. to San Francisco, often in response to citizen pressure.

Cutting methane would do more than just stabilize climate. It would also help to reduce the harmful health effects of smog, since methane is a key ingredient in the formation of ground-level ozone. The UN report estimates that a 45 percent reduction in methane emissions would prevent 260,000 premature deaths and 775,000 asthma-related hospital visits.

Nickolas Themelis is a professor emeritus at Columbia Engineering. He is one of 35 scientists to send a letter to U.S. climate envoy John Kerry and national climate advisor Gina McCarthy calling on the U.S. to eliminate landfill methane emissions. He was joined by three other Columbia professors: Athanasios Bourtsalas, Kartik Chandran, and Steve Cohen.

This column is editorially independent of Columbia News.