Methane from livestock has long been a major driver of global warming. Free-range cattle contribute less intensity per animal, but large operations housing hundreds or thousands of animals amplify emissions, turning livestock into significant sources of this heat-trapping gas.
Worldwide, cattle and other livestock release an estimated 3.1 billion metric tons of methane each year. Methane is far more potent than carbon dioxide at trapping heat over shorter timescales, making it a central climate challenge for policymakers and farmers alike.
Methane stays in the atmosphere longer than some expect and accounts for a sizable share of warming. In simple terms, a small herd can rival a small fleet of polluting vehicles in its climate impact. The digestive process in ruminants like cattle is a key contributor and has attracted attention from environmental agencies around the globe.
The European Union has laid out ambitious plans to cut methane from livestock, aiming for a meaningful decline by 2050 and promoting innovative approaches to reach those targets.
Algae, unexpected allies
Over the years, researchers have begun to see algae as a potential ally in reducing methane. In 2016, studies from Australia showed that certain seaweeds could lower emissions from cattle. In laboratory tests, the red alga Asparagopsis taxiformis, once seen as an invasive species in parts of the Mediterranean, demonstrated real promise in decreasing methane production.
By 2019, trials adding trace amounts of this algae to cattle feed reported substantial reductions in methane, ranging from about 40% to almost complete suppression. A later study from a major university in the United States confirmed these effects, with researchers noting sustained reductions when seaweeds are fed to livestock and that benefits could persist over time. (Citation: Frontiers in Sustainable Food Systems, 2023)
High-net-worth investors have taken notice. Bill Gates, among others, has shown interest in funding Australian startups developing seaweed-based feed aids. Companies such as DSM began marketing similar products around the end of 2021, signaling a broader shift toward methane mitigation in the livestock sector.
Another approach: algae in manure
Researchers are exploring a second approach: introducing algae directly into manure. A recent study published in the Sustainable Food Systems field reported promising results when seaweed was excreted with feces, suggesting another pathway to reduce methane releases from manure.
In trials where algae was added to cow dung, methane production dropped by about 44% in cows that received the additive with their feed. As one Swedish agricultural scientist noted, while dairy-diet studies have been plentiful, there has been less exploration of how these additives perform in manure management and storage. (Citation: Frontiers in Sustainable Food Systems, 2023)
Emissions from storage, including fertilizer-related contributions, vary with conditions. In cool, temperate European storage environments, manure accounts for roughly 12% of methane emissions from the dairy sector. This underscores the importance of managing storage alongside dietary interventions.
For researchers and policymakers, ongoing findings emphasize a multifaceted strategy that blends feed additives with manure management practices. This integrated approach could help reduce the footprint of the dairy and beef sectors while preserving productivity. (Citation: Frontiers in Sustainable Food Systems, 2023)
Note on data and references: the field’s work continues to evolve as new studies are published and peer-reviewed. Researchers stress that outcomes can vary with diet composition, climate, and farm practices.