By: Ava Sergio
Photo from: Smithsonian Ocean Institution
Seaweeds have been sending carbon to the seafloor and deacidifying oceans for generations (Gerretsen, 2021). Through innovation and research, scientists have recently discovered their untapped potential as a climate crisis solution.
What is seaweed?
Seaweed is an umbrella term for countless marine plant species. Two commonly known types of seaweed are kelp and algae. Seaweeds come in three main colour classifications: red, brown, and green. Seaweeds also range in sizes from microscopic phytoplankton to giant kelp forests.
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How does seaweed fight the effects of climate change?
Seaweeds could be our secret weapon in the fight to mitigate climate change. Firstly, seaweed removes carbon dioxide (CO2), the most abundant greenhouse gas emitted through anthropogenic activities, from the ocean and atmosphere. They absorb CO2 through photosynthesis and sequester it within their roots and soil. It’s estimated that globally, seaweeds sequester nearly 200 million tonnes of carbon dioxide every year, that’s as much as New York State’s annual carbon emissions (Gerretsen, 2021).
Photo from: Matthew Riddle
Removing carbon dioxide from our oceans is important because it lowers ocean acidification. When carbon dioxide dissolves in seawater, it forms carbonic acid. This acid accumulates in the ocean and the water becomes more acidic, making the pH drop. Ocean acidification has many negative consequences that are being seen globally. As the ocean waters become increasingly corrosive, it gets more difficult for marine life to build their protective shells and skeletons. This is because they use a chemical called carbonate as the base of these shells and skeletons, however, carbonic acid significantly reduces carbonate levels in the water.
According to the United States Environmental Protection Agency, some of the most affected animals in 2016 included clams, oysters, mussels, corals, and starfish. The marine life listed supports an ocean-wide food web, and are highly important to coastal economies. According to NOAA US Fisheries, the estimated value of the shellfish industry in 2016 was $340 million with oysters making up 37 million pounds of the total 47.9 million pounds of shellfish recorded that year.
Seaweed’s potential as a climate crisis solution
Photo from: Aquaculture North America
Seaweed farming is starting to gain momentum in many parts of the world as a result of the growing awareness of the species’ ability to combat climate change, its high nutritional value, and fast growth. In fact, an estimated 48 million square kilometres of the world’s oceans are suitable for seaweed growth, which sums to an area six times larger than Australia (Gerretsen, 2021). This provides more than enough land mass to scale up seaweed production and growth to a much greater level. Another benefit of seaweed is its extremely high growth rate. Large brown kelp is one of the fastest growing seaweeds that is thought to grow about 2 feet per day and requires no fertilizer or weeding.
In a recent interview with Emily Pidgeon, the senior director at Conservation International, she stated that coastal marine ecosystems can absorb carbon at rates up to 50 times faster than land forests. When seaweeds die, much of the carbon stored within the plants is deposited deep into the ocean to be processed naturally rather than being released back into the ecosystems at risk. Much of the research being conducted on seaweed farming indicates that seaweed has a strong potential as a climate crisis solution.
How realistic is it?
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To determine the serious ability of seaweed to alleviate climate change is the first step, the second is to determine how realistic it is to implement. Researchers around the world are seeming to come to a consensus that seaweeds are a powerful climate sink and a strong and sustainable solution to the climate crisis. For example, a marine scientist at UC Santa Barbara named Halley Froelich performed a study that found farming seaweed in just 3.8% of federal waters off the coast of California could offset all the carbon emissions from the state’s fifty billion dollar agriculture industry. Studies like this are proving that seaweed is absolutely a realistic solution.
What are some of the challenges?
Like most marine species, seaweeds do not thrive in acidic waters and higher temperatures. As our oceans increase in temperature and acidity, they become less inhabitable for seaweeds. If these remarkable plants are not able to grow and absorb carbon dioxide in our oceans, then we will lose the incredible ecosystems they create. It’s estimated that Tasmania has already lost about 95% of it’s kelp forests. Once seaweeds such as kelp are gone from their environment, it’s very hard to reintroduce them because the environment simply doesn’t support them anymore.
The many uses of seaweed farms
Another way to use seaweeds is to farm them in replacement of carbon-intensive technologies in food production and materials production. According to scientists, even just a 10% replacement of seaweed in wheat or meat production would have a significant environmental impact. Seaweed farming requires no chemicals or fertilizers and it’s even been farmed to produce biodegradable plastic. As a whole, seaweeds are thought to be able to replace a myriad of materials including: plastic, animal feed, foods, biomaterials, and conventional biofuel.
Biodegradable plastic made from seaweed.
Photo from: GreenBiz
Combined with a transition to 100% clean, renewable energy that tackles fossil fuels, seaweeds could become one of the largest ways we fight ocean acidification in just a couple years. Seaweed farms are a strong and sustainable climate crisis solution that is deserving of our research and attention.
Discussion Questions:
What other threats exist that are harming seaweeds globally?
What are some disadvantages to using seaweed farms to fight ocean acidification that weren’t mentioned in this article?
Sources:
Gerretsen, I. (2021, April 14). The remarkable power of Australian kelp. BBC: Future Planet. https://www.bbc.com/future/article/20210406-how-kelp-can-help-solve-climate-change
Harrison J, Carter KB. (2021, March 25). The miraculous power of the humble seaweed. BBC: Reel. https://www.bbc.com/reel/video/p09bqf8t/the-miraculous-power-of-the-humble-seaweed
National Oceanic and Atmospheric Administration. (2016, April 1). Ocean acidification: A wake-up call in our waters. https://www.noaa.gov/ocean-acidification-high-co2-world-dangerous-waters-ahead
National Oceanic and Atmospheric Administration. (2021, February 26). What is seaweed? National Ocean Service. https://oceanservice.noaa.gov/facts/seaweed.html
National Oceanic and Atmospheric Administration Fisheries. Understanding Shellfish Aquaculture. [accessed May 31, 2021]. https://www.fisheries.noaa.gov/insight/understanding-shellfish-aquaculture
United States Environmental Protection Agency. (2016, December 21). Effects of Ocean and Coastal Acidification on Marine Life. https://www.epa.gov/ocean-acidification/effects-ocean-and-coastal-acidification-marine-life