Credit: Sayid Budhi

Coming Attractions

A Cow Walks Onto A Beach

Ruminants, such as cows, sheep, and goats, have a special digestion process that produces large quantities of methane, which has a warming effect 34 times more powerful than carbon dioxide. Ruminant methane accounts for 6 to 7 percent of annual greenhouse gas emissions. Seaweed, which has been used as livestock feed for thousands of years, shows promise for reducing them.

Building on anecdotal evidence from dairy farmers, a team of scientists in North Queensland, Australia, have tested a wide range of seaweeds mixed with feed in artificial cow stomachs. Asparagopsis taxiformis, a species of red algae, reduced methane production by 99 percent—and required a dose of just 2 percent of feed to do so. In live sheep, the same dose led to a 70 to 80 percent drop in methane. Tests have yet to be performed with live cows.

With more than 1.4 billion cows and nearly 1.9 billion sheep and goats inhabiting the planet, scale is a major challenge for this solution. Champions argue it is well worth cracking. If fed to ruminants worldwide, Asparagopsis taxiformis would reduce the amount of soy, corn, and grass required as feed. Most critically, it could dramatically reduce livestock methane emissions.

References

Seaweeds…used as livestock feed: Makkar, Harinder P.S., Gilles Tran, Valérie Heuzé, Sylvie Giger-Reverdin, Michel Lessire, François Lebas, and Philippe Ankers. “Seaweeds for Livestock Diets: A Review.” Animal Feed Science and Technology 212 (2016): 1-17.

Prince Edward Island…dairy farmer: Battaglia, Michael. “Seaweed Could Hold the Key to Cutting Methane Emissions from Cow Burps.” The Conversation. October 12, 2016.

Methane…dropped…on Dorgan’s diet: Kinley, R. D., and A. H. Fredeen. “In Vitro Evaluation of Feeding North Atlantic Stormtoss Seaweeds on Ruminal Digestion.” Journal of Applied Phycology 27, no. 6 (2015): 2387-2393.

methane waste expelled…through burps: Battaglia, “Seaweed.”

39 percent of [livestock] emissions: Gerber, P.J., et al. Tackling Climate Change Through Livestock: A Global Assessment of Emissions and Mitigation Opportunities. Rome: Food and Agriculture Organization of the United Nations, 2013.

a quarter of…methane pollution: Reay, D., et al. “Methane Sources and the Global Methane Budget.” In Methane and Climate Change, edited by D. Reay et al, 1-14. London: Earthscan, 2010.

Australia, methane…emissions: Henry, Beverley, Ed Charmley, Richard Eckard, John B. Gaughan, and Roger Hegarty. “Livestock Production in a Changing Climate: Adaptation and Mitigation Research in Australia.” Crop and Pasture Science 63, no. 3 (2012): 191-202.

Asparagopsis taxiformis: Guiry, M.D., and G.M Guiry. AlgaeBase. Galway: National University of Ireland. 2016. http://www.algaebase.org.

results…artificial rumen: Kinley, Robert D., Rocky de Nys, Matthew J. Vucko, Lorenna Machado, and Nigel W. Tomkins. “The Red Macroalgae Asparagopsis Taxiformis Is a Potent Natural Antimethanogenic That Reduces Methane Production During In Vitro Fermentation with Rumen Fluid.” Animal Production Science 56, no. 3, 2016: 282-289; Machado, Lorenna, Marie Magnusson, Nicholas A. Paul, Robert Kinley, Rocky de Nys, and Nigel Tomkins. “Dose-Response Effects of Asparagopsis Taxiformis and Oedogonium Sp. On In Vitro Fermentation and Methane Production.” Journal of Applied Phycology 28, no. 2, 2016: 1443-1452; Machado, Lorenna, Marie Magnusson, Nicholas A. Paul, Rocky de Nys, and Nigel Tomkins. “Effects of Marine and Freshwater Macroalgae On In Vitro Total Gas and Methane Production.” PLoS One 9, no. 1 (2014): e85289.

results…live sheep: Li, Xixi, Hayley C. Norman, Robert D. Kinley, Michael Laurence, Matt Wilmot, Hannah Bender, Rocky de Nys, and Nigel Tomkins. “Asparagopsis Taxiformis Decreases Enteric Methane Production from Sheep.” Animal Production Science (2016); Rupp, Rebecca. “A Sprinkle of Seaweed Could Deflate Gassy Cows.” National Geographic. November 29, 2016.

energy…[lost] to waste methane: Van Nevel, C. J., and D. I. Demeyer. “Control of Rumen Methanogenesis.” Environmental Monitoring and Assessment 42, no. 1-2 (1996): 73-97.

[population of] cows…sheep and goats: Robinson, Timothy P., GR William Wint, Giulia Conchedda, Thomas P. Van Boeckel, Valentina Ercoli, Elisa Palamara, Giuseppina Cinardi, Laura D’Aietti, Simon I. Hay, and Marius Gilbert. “Mapping the Global Distribution of Livestock.” PloS one 9, no. 5 (2014): e96084.

[scale] of seaweed farms: Kirby, David. “How to Stop Farts from Warming the Planet: Feed Cows Seaweed.” TakePart. October 25, 2016.

Feed production and processing…emissions: Gerber et al, Livestock.

limu kohu…“pleasing seaweed”: Guiry and Guiry, AlgaeBase.

livestock methane…percent of greenhouse gases: Gerber et al, Livestock.

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Errata

p. 205

Most critically, Asparagopsis taxiformis could dramatically reduce livestock methane emissions, which now account for 6 to 7 percent of greenhouse gases released around the world each year.

view all errata

Methodology and Results

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Coming Attractions
Enhanced Weathering of Minerals
Natural weathering of silicate rock sequesters carbon dioxide. Enhanced weathering aims to hasten that process by milling rock powder and applying it to landscapes.
Coming Attractions
Artificial Leaf
The artificial leaf is technology inspired by photosynthesis. It combines solar energy, water, and carbon dioxide, to feed bacteria that synthesize energy-dense fuel.
Coming Attractions
Direct Air Capture
Direct air capture systems are a nascent sequestration technology. Functioning like a chemical sieve and sponge, they capture carbon dioxide from air and release it in purified form.
Coming Attractions
Repopulating the Mammoth Steppe
A vast ecosystem called the mammoth steppe once dominated the frozen north. Restoring grazers and grassland could prevent carbon-rich permafrost from thawing and releasing emissions.
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