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Kelp and Carbon

A business of the future

Louis Pelton could be a farmer of the future. Not the type of farmer who awakens each morning to till the land, milk the cows, or feed the livestock. But instead, the kind of farmer who rises early and takes his boat into the open oceans. He prefers for fish to roam free and not spend their lives in small fetid enclosures, and he has no interest in catching them. Ironically Louis’ business provides his onshore farming brethren with needed food and supplements for their traditional enterprises. He supplies the world with nutrient-packed food in the form of kelp — the Louis of the future is an algae farmer.

Thoughts of algae may conjure up images of watery slime in a summer lake, or perhaps toxic algae blooms, resulting in massive fish kills. But algae can be big, and the largest algae species on the planet is giant kelp. The phrase “sequoias of the sea” refers to California’s kelp forests. Individual plants grow up to 175 feet above the ocean floor under ideal conditions. Kelp is the anchor species for local ecosystems along the southern California Coast and northward to Santa Cruz.

Kelp has no roots. Instead, it attaches to rocks on the seafloor via a structure called a “holdfast.” From that holdfast, it can then tower upward from the bottom, growing at rates of up to two feet a day. The kelp has a trick to keep it upright. Attached to every blade (leaf) on the plant is a gas-filled pod. Thus, buoyancy naturally sends the plant towards the ocean’s surface, keeping it upright.

Coastal marine kelp ecosystems support an intricate and interdependent web of life. Hundreds of marine species live in the kelp forests and rely on the kelp for their survival. Gray whales shelter their young there. Sea otters hunt for food among the towering kelp plants, and commercial abalone fisheries also depend on the kelp.

Who eats algae?

Louis can’t run his business without customers, but who wants algae? The kelp market is currently larger than you might expect, and it will only grow larger with time. Kelp is consumed by humans, processed for various chemicals, and also used as animal feed. Take a trip to your local health-supplement store, and you will probably find kelp powder on the shelves. Then, there are shampoos, toothpaste, salad dressings, and more, all of which use kelp products.

Approximately 150,000 tons of kelp are harvested in California waters each year. But future kelp farmers like Louis will expand both the harvest and the markets, and one of these markets is cattle feed.

The world loves its bovine friends, particularly when they are served medium rare. The world consumed 61 million metric tons of beef in 2018, with the U.S. accounting for 21 percent of that demand. Beef production worldwide has more than doubled since 1960. However, the U.S. beef-cattle headcount fell from 45 million in the early 1970s to 31 million in 2020. High demand and declining supplies help explain the skyrocketing prices paid for tenderloin cuts at your local grocer.

However, cows come in more than just the beef variety, and the worldwide cattle headcount is currently about 1.4 billion.

Cows and climate Change

Lots of cows roam the planet. The average cow produces between 70 to 120 kilograms of methane each year from rumination (their digestive process), leading to over 100 million metric tons of methane released into the atmosphere annually. This contribution accounts for roughly one-third of the total annual methane from Anthropogenic (human) sources and about 20 percent of all methane from combined natural and human sources.

Methane is a powerful enabler of climate change because it is a “super greenhouse gas,” up to 80 times more potent than carbon dioxide. However, researchers have found that adding kelp to animal feed cuts a cow’s methane production by 60 percent. This reduction is potentially significant since each year farmer’s livestock pump out enough methane to equal the warming capacity of 7 gigatons of carbon dioxide. So, a little kelp could go a long way in combating global warming.

Our planet is changing, and businesses filling the dual role of providing needed commercial products and reducing greenhouse gases will be sorely needed in the near future. A warmer planet is on its way, and managing carbon pathways in agriculture is critical for creating a sustainable world where our children can thrive.

Kelp and carbon

Healthy kelp forests also act as a chemical buffer. They provide fast-growing biomass that effectively sequesters carbon by removing carbon dioxide from the ocean water. The kelp uses CO2 for photosynthesis and produces oxygen as a by-product. So, the high biomass of kelp in a forest ensures that the surrounding waters remain well oxygenated.

The absorption of CO2 by the kelp provides another added benefit to the ecosystem. It reduces the acidity of the local water. Carbonate buffering is the name given to the CO2 exchange process between the atmosphere and the oceans. When the CO2 enters the ocean, it reacts with water to form carbonic acid, and this causes ocean acidification.

But the removal of CO2 from the ocean waters lowers ocean acidity. This change helps organisms from plankton to crabs by keeping their shells strong. If acidity weakens a species like plankton at the base of the food chain, then all species in the ecosystem come under stress, so lower acidity helps local ecosystems thrive.

How to farm kelp

Harvesting kelp involves taking off the top four feet of the kelp plants and then returning when they reach the surface again, thus allowing several harvests each season. The process preserves the kelp forest ecosystem, and in the State of California, it’s regulated, ensuring commercial kelp beds become a sustainable resource for future generations.

But companies and farmers are working on more innovative farming techniques. Off the coast of California, an experimental kelp elevator is testing new ways to farm the ocean. Kelp is attached to a large PVC structure with a solar-powered buoy controlling the depth of the kelp. During the day, the kelp is suspended near the surface to receive sunlight for photosynthesis. However, at night the buoy lowers the PVC structure to depths of 260 feet.

During the night, the kelp absorbs extra nutrients from the cool, deeper water. Then, during the day, the combination of sunlight and extra nutrients allows the kelp to grow faster than if it stayed permanently at the surface. Kelp on the elevator grows three times faster and weighs four times more than kelp grown only at the surface.

Kelp plants are algae with environmental and commercial value. Maintaining existing kelp forests, re-growing old ones, and creating new open-water habitats are all sensible options. Sustainable, productive ecosystems are a win for everyone, and ocean farming of kelp will probably prove to be a lucrative business for Louis and others on our rapidly warming planet.


California kelp forests: Ecosystems in distress (Source: ArcheanWeb) 

Hot ocean waters affecting New Zealand kelp (Source: ArcheanWeb) 

Giant Kelp (Macrocystis pyrifera) (Source: Oceana) 

California’s critical kelp forests are disappearing in a warming world. Can they be saved? (By Todd Woody; National Geographic) 

How do people use kelp? (Source: NOAA) 

Seaweed could make cows burp less methane and cut their carbon hoofprint (By: James Temple; MIT Technology Review) 

Giant Kelp (Source: California DFG) 

World Beef Consumption: Ranking Of Countries (By Rob Cook; Beef2Live) 

Beef Cows inventory (Source: USDA) 

Methane, explained (By ALEJANDRA BORUNDA; National Geographic) 

Methane Tracker 2020 (Source: IEA) 

Water scarcity and fish imperilment driven by beef production (By Brian D. Richter, Dominique Bartak, Peter Caldwell, Kyle Frankel Davis, Peter Debaere, Arjen Y. Hoekstra, Tianshu Li, Landon Marston, Ryan McManamay, Mesfin M. Mekonnen, Benjamin L. Ruddell, Richard R. Rushforth1 and Tara J. Troy; Nature) 

William House
William is an earth scientist and writer with an interest in providing the science "backstory" for breaking environmental, earth science, and climate change news.