America’s landfills are ‘garbage lasagnas’

Landfills are also a hotbed for waste, from decomposing vegetable scraps and meat bones to worn household appliances, which produce copious amounts of methane, a greenhouse gas with a warming effect 80 times as powerful as carbon dioxide over a 20-year period. 

A new study published in the journal Science found the rate of methane emissions from landfills is three times as large as the rate previously reported to federal regulators. In combination with methane’s high potency, the study’s findings add to a growing body of evidence about how landfills around the globe significantly contribute to global warming and highlight the need for reforms, both in the infrastructure of landfills and the way Americans dispose of waste. 

The study used a new technology, an imaging spectrometer, which measures electromagnetic radiation to detect and measure processes in the Earth’s atmosphere, to collect data on methane emissions from 20% of the country’s largest landfills. Before the advent of this technology, estimates of methane emissions were based mostly on computer models, which, according to the study, are less than optimal, given the unique circumstances of each landfill and its operational oversight. Previously reported methane emission estimates are also likely lower than reality, as a result of the dangerous nature of manually measuring emissions at landfills, which require workers to walk around dumps with handheld sensors.

Landfills often contain layers upon layers of garbage, encompassing everything from decomposing food scraps and plastic to household appliances and paper, that pile up for decades. When food waste ends up buried in these layers, it decomposes without much oxygen and, as a result, releases methane. 

“You can sometimes get decades of trash that’s sitting under the landfill,” according to Daniel Cusworth, the lead author of the study and a climate scientist at the University of Arizona. As he told the New York Times, “We call it a garbage lasagna.”

Among the most common atmospheric greenhouse gases, methane isn’t the most abundant or the longest-lasting in the atmosphere, but its potent warming effect is 80 times as powerful as the most common greenhouse gas,…