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Nearly half of the solid waste produced globally is organic or biodegradable. Much of it ends up in landfills; there, it decomposes in the absence of oxygen and produces the greenhouse gas methane, which is up to 34 times more powerful than carbon dioxide over a century. While many landfills have some form of methane management, it is far more effective to divert organic waste to composting.

Composting ranges in scale from backyard bins to industrial operations. The basic process is the same: ensuring sufficient moisture, air, and heat for soil microbes (bacteria, protozoa, and fungi) to feast on organic material. Rather than generating methane, the composting process converts organic material into stable soil carbon, while retaining water and nutrients of the original waste matter. The result is carbon sequestration as well as production of a valuable fertilizer.

Human beings have long used compost to feed gardens and fields. Today, it is especially useful for managing growing urban waste streams. In 2009, San Francisco passed an ordinance that makes composting the city’s food waste mandatory. Copenhagen, Denmark, has not sent organic waste to landfill in more than twenty-five years, reaping compost’s win-win-win of cost savings, fertilizer production, and reduced emissions.


Albert Howard…champion of compost: Howard, Sir Albert. The Soil and Health: A Study of Organic Agriculture. New York: Devin-Adair Company, 1947.

nitrogen fertilizers…Fritz Haber and Carl Bosch: Erisman, Jan Willem, Mark A. Sutton, James Galloway, Zbigniew Klimont, and Wilfried Winiwarter. “How a Century of Ammonia Synthesis Changed the World.” Nature Geoscience 1, no. 10 (2008): 636-639.

Antoni van Leeuwenhoek; “wee beasties”: Montgomery, David R., and Anne Biklé. The Hidden Half of Nature: The Microbial Roots of Life and Health. New York: W.W. Norton & Co., 2016.

solid waste…organic or biodegradable: Hoornweg, Daniel, and Perinaz Bhada-Tata. What a Waste: A Global Review of Solid Waste Management. Washington, D.C.: The World Bank, 2012.

methane [vs.] carbon dioxide: Myhre, Gunnar, Drew Shindell, François-Marie Bréon, William Collins, Jan Fuglestvedt, Jianping Huang, Dorothy Koch et al. “Anthropogenic and natural radiative forcing.” In Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK, and New York: Cambridge University Press, 2013.

San Francisco…ordinance: Howard, Brian Clark. “How Cities Compost Mountains of Food Waste.” National Geographic. June 18, 2013.

Seattle…composting requirement: Ferdman, Roberto A. “Seattle is Now Publicly Shaming People for Putting Food in Their Trash Bins.” Washington Post. January 27, 2015.

Copenhagen…[no] organic waste to landfill: Levitan, Dave. “Recycling’s ‘Final Frontier’: The Composting of Food Waste.” Yale Environment 360. August 8, 2013.

“flesh is the soil”: da Vinci, Leonardo, and Jean Paul Richter. The Literary Works of Leonardo da Vinci. London: Phaidon, 1970.

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