Can seaweed mitigate methane from cows on a global scale?

Livestock have eaten seaweed for thousands of years, in coastal areas and in times of scarcity. Seaweed is abundant, accessible, and mineral-rich (1). But over the past decade, researchers have been steadily gathering evidence suggesting that, under the right conditions, it may also help address a significant modern-day challenge.

Of the methane caused by human activity—a major driver of climate change—almost one-third comes from livestock—cows in particular—in the form of enteric methane (2, 3). This potent greenhouse gas is produced in parts of an animal’s stomach called the rumen, largely by archaea combining hydrogen and CO2 generated as other microbes ferment feed (4), and released mostly when animals belch (5). Because methane has more climate-warming potential but a shorter lifespan than carbon dioxide, curbing methane emissions could have a major role in limiting climate change in the short term (6).

Researchers like Ermias Kebreab, an animal scientist at the University of California Davis (UC Davis), think feed additives should be part of the solution—and seaweed or synthetic derivatives are the “most effective ones that we have ever seen,” he says.