The latest IPCC report is blunt – our planet is on track to reach at least 1.5°C of warming by 2050, under all emissions scenarios considered. Deep reductions in CO2 and other greenhouse gas emissions will be required to limit further warming and the devastating physical impacts associated with it, which we are already beginning to experience – certain communities more than others.
Faced with this reality, more than 100 countries committed to a “Global Methane Pledge” at the 2021 United Nations Climate Change Conference (COP26), lasering in on methane (CH4) as a way to slash emissions within a shortened time frame.
Methane is a powerful greenhouse gas and is especially strong in the short term – 80 times more potent than carbon dioxide on a 20-year time frame, and 28 times more potent on a 100-year time frame. The IPCC reports that methane concentrations have increased rapidly since 2007, largely driven by fossil fuels and agriculture sectors. However, methane has a relatively short residence time in the atmosphere – it breaks down after about 12 years on average.
Therefore, targeting methane sources now will reduce atmospheric GHG concentrations with effects that will be felt in just a decade or two – which is critical for limiting warming by 2050.
And not only is reducing methane emissions imperative, it’s achievable: The UNEP Global Methane Assessment, published this year, reports that currently available mitigation strategies could achieve a 45% reduction in emissions, which would prevent nearly 0.3°C warming. Separately, a 2021 Environmental Research Letter concluded that “Overall, strategies exist to cut global methane emissions from human activities in half within the next ten years and half of these strategies currently incur no net cost.”
Food Waste is a Top Methane Contributor
Municipal solid waste landfills accounted for 15% of US methane emissions in 2019, making them the third largest source. And it turns out that food waste is the number one most prevalent material in our landfills – EPA estimates that in 2018, food scraps accounted for 24% of material sent to landfill. So not surprisingly, food waste is the main contributor to methane coming from landfills, which is produced from the decomposition of organic matter (food, yard trimmings, etc.) in solid waste under anaerobic (no/low oxygen) conditions.
The largest source of methane in the U.S. is actually the agricultural sector, particularly livestock operations. EPA just announced it will be rolling out new methane standards for the oil and gas industry, which is an important step towards regulating these polluting entities. However, we should not lose focus on addressing methane sources across all responsible sectors.
The highest priority for reducing methane emissions to the maximum extent feasible should be investment in upstream solutions that target food waste prevention at the source. Diverting unavoidable food waste to alternative destinations such as composting and anaerobic digestion, which convert the scraps into beneficial and useful biomaterials, is necessary to reduce methane emissions from landfill. But not only do prevention solutions avoid methane emissions when waste decomposes in landfill, they also prevent the formation of additional greenhouse gases at other stages of the supply chain, including agricultural production. Of the solutions modeled by ReFED to meet the national goal of reducing food waste 50% by 2030, prevention programs are responsible for 87% of the expected emissions reductions.
“Cutting methane is the strongest lever we have to slow climate change over the next 25 years and complements necessary efforts to reduce carbon dioxide,” says Inger Anderson, Executive Director of UNEP. “The benefits to society, economies, and the environment are numerous and far outweigh the cost.”