There is some good news about methane in large animal feed operations

If their by-products are treated in digesters to capture the methane gas which is produced. Some of these larger farm operations are collecting manure in large tanks, mixing it in an oxygen-free environment and heating it. Micro-organisms break down the organic material and methane is captured and then burned to produce heat and electricity for the farms. What is left of the organic material is used as fertilizer. Of course, burning the methane produces carbon dioxide, but reducing the methane is still a net gain for our climate because we avoid burning additional oil and gas from underground. Most farms don’t do this because of small scale and monetary considerations.

Digesters use manure, municipal sewage sludge, food waste from all sources, and other organics from fats, oils, grease, crop residue to winery/brewery waste. Food waste makes up the largest category dumped in municipal landfills. Massachusetts banned dumping food and other organic waste by restaurants, grocers, and large institutions in 2014, and the number of large digesters in the state has increased since then to nine. Companies and restaurants send food waste to them for processing. California is increasing its use of digesters with grant incentives and regulations. As you might expect, this method of waste disposal is met with resistance from the waste industry and the inertia of public opinion. “For 400 years this country picked up garbage and either put it in a hole and buried it, or burned it”, commented Patrick Serfass, executive director of the American Biogas Council.

Some environmental groups believe the best way to cut methane is to keep farms small and expose manure to the air, where oxygen stops the conversion to methane. About a third of the methane emitted each year comes from natural sources: wetlands, hydrothermal vents, and hot springs. But two-thirds of the methane in the air is generated by human activity. Oil, natural gas, and coal-mining infrastructure contribute about 35 percent of this amount, with human waste and landfills contributing another 20 percent. Agriculture produces most of the remaining 45%.

Why should we be concerned about methane? It traps more heat in the earth’s atmosphere than carbon dioxide, but only lasts about 12 years in the atmosphere before breaking down into water and
carbon dioxide. Carbon dioxide traps less heat, but lasts generations in the atmosphere, with a small amount lasting thousands of years, making it a difficult long-range problem. Cutting methane emissions has the advantage of being able to affect global temperature more quickly, reducing sea level rise and human suffering from extreme weather. Fires, heat waves, floods and droughts have been increasing at a faster rate than climate scientists’ worst-case scenarios, so reducing methane can be extremely useful to mitigate some of these most immediate effects. Methane oxidized on the ground also forms ozone, a respiratory hazard.

The concept of reducing our consumption of meats and dairy, laughed at by some, is indeed another way to reduce our methane production.

-Excerpted from Smithsonian Magazine, April/May 2023
Sandy McKitrick, Climate Care Team