Kelp Farming
The Facts
Seaweed can play a huge role in fighting climate change by absorbing carbon emissions, regenerating marine ecosystems, creating biofuel and renewable plastics as well as generating marine protein. Until recently, this centuries old industry has mainly farmed seaweed for food in Asia, with China as the world’s biggest producer of seaweed, accounting for 60% of global volume. But over the past decade, global seaweed production has doubled—with an estimated value of $59.61 billion in 2019—as interest in seaweed as a food source, carbon sink option and renewable product from consumers, farmers, researchers, and business leaders blossoms. By creating more kelp farms we can pull more carbon out of the atmosphere and simultaneously feed a hungry world as well as restore sea life.
While forests have long been considered the best natural defense in the battle against climate change, researchers have found that seaweed is in fact the most effective natural way of absorbing carbon emissions from the atmosphere. Unlike tree planting, seaweed does not require fresh water or fertilizers and grows at a much faster rate than trees, expanding by up to two feet a day. But seaweed’s biggest comparative advantage is that it does not compete for demands on land.
Given concerns about the environmental impact of eating meat, seaweed—which itself is a source of protein—could be an eco-friendly and nutrient packed food source in the coming years. Ronald Osinga of the Wageningen University in the Netherlands found that growing “sea-vegetable” farms totaling 180,000 square kilometers—roughly the size of Washington State—could provide enough protein for the entire world. California oceans could feed the world!
Seaweed can also help reduce greenhouse gas emissions in other ways: adding a small amount of Asparagopsis taxiformis—a red algal species—to cattle feed has the potential to reduce methane production from beef cattle by up to 99%.
California is rich in coast line and boasts a bountiful ocean ready to combat climate change.
“When you look at how we are going to feed the world population by 2050 in a way that doesn’t harm the environment, there is only one pathway,” says Carlos Duarte, a researcher and professor in biological oceanography and marine ecology. “To scale up seaweed farming.” California’s oceans could be a big part of the solution to feeding the world and solving climate change.
The Claim
Seaweed has been removing carbon dioxide from the atmosphere for at least 500 million years. Recent studies suggest that wild seaweed continues to do humanity a solid by sequestering 173 million metric tons annually. The average square kilometer of seaweed can sequester more than a thousand metric tons.
How It's Supposed to Work
Kelp spores are grown in a lab and then sprayed onto spools of string. These are cultivated for several weeks until the kelp spores have grown fuzzy like Chia Pets. The string is then wound around ropes and dropped into the ocean for six to eight months, until the kelp plants reach maturity.
If the kelp were being harvested, boats would then come out and collect the ropes. But to sequester the carbon captured by the kelp, the plants need to be sunk at least 1,000 meters deep, where they will decay and not return to the surface to rejoin the carbon cycle. (The standard measure of success is removing CO2 for at least 100 years.) Researchers are studying the best ways to sink the kelp—perhaps by using biodegradable buoys.
50 billion metric tons of greenhouse gases are emitted globally every year. Kelp farms would need to be significantly scaled up to create an impact. California oceans provide a great way to scale up and solve this issue.
In addition to sequestering carbon, it can provide habitat for fish and mitigate local effects of ocean acidification. Unlike other forms of aquaculture, it doesn't depend on inputs like fish feed or antibiotics that can throw local ecosystems out of whack.
Still, the most effective way to sequester carbon is to not release it in the first place. For example, scientists recently calculated that bottom trawling (a fishing method that involves scraping the ocean floor with giant nets) releases as much carbon into the atmosphere as the entire aviation industry does—about a billion metric tons a year. A global ban on trawling could accomplish a lot on global emissions. Kelp farms in California oceans done in mass scale is a single great solution to combat many problems.