The Seaweed Solution to Climate Change

Seaweed is one of the most straightforward crops to grow. All it requires is light and nutrients that are already present in the seawater. Along with being simple to grow, they don’t need any harmful fertilizers or promote deforestation and other negative land-use changes. [1] Greenwave are currently designing vertical farms of seaweed and shellfish, which are low maintenance and have a minimal carbon footprint. [2]

Seaweed has massive potential as a carbon sink. Like all primary producers, seaweed takes up carbon from its surroundings to use in photosynthesis, but it can also bury carbon in sediment after the plant has died. [3] In this article, we will look more closely at potential uses for seaweed farms.

Seaweed is a Carbon Sink

Seaweeds can sequester 20 times more CO2 per acre than land forests. When seaweed branches die, they can fall to the ocean floor and be covered by sediment, maintaining a low oxygen environment and effectively taking the carbon out of the ecosystem for good. [4]

Seaweeds are a “blue carbon” sink. They store significant amounts of carbon and can play a huge role in mitigating anthropogenic climate change. [5]

Seaweed Reverses Ocean Acidification

The ocean itself is a massive carbon sink, absorbing an ever-increasing amount of carbon from the atmosphere per year. Unfortunately, this causes the pH of the water to decrease, becoming more acidic. The ocean’s proclivity to take up atmospheric carbon, in turn, causes problems such as coral bleaching. [6]

Fig 1: Graph from NASA showing the ocean uptake of anthropogenic CO2 each year

Seaweed has the potential to reverse the process somewhat. The absorption of carbon from the ocean can increase the pH of the water, reversing acidification on a local scale. In this respect, seaweeds can act as a buffer. [7]

Seaweed Can Prevent Coastal Erosion

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Seaweed can help safely dissipate wave energy and protect our coastlines. A study by Kim, Jeon and Yoon discovered that the coast might advance after storms due to increased deposition of sediment and other material on beaches. [8]

Seaweed Can Replace Plastic Packaging

At the London marathon this year, runners were offered water to drink along the course. The difference this year is that instead of using and wasting an estimated 760,000 plastic water bottles, runners were handed their drinks in over 30,000 edible seaweed pouches. These pouches are not only edible but also biodegrade in approximately the same amount of time as a piece of fruit. [9]

Despite being able to degrade so quickly, most seaweed packaged products can have up to two years of shelf life. Seaweed may be the future packaging used for single-serving sachets of coffee in hotel rooms or to package soaps. [10]

We dump eight million tons of plastic each year, and seaweed can do all the same things but in a cleaner, zero waste way. Only 9% of plastic is currently recycled, and every piece of plastic ever produced is still somewhere in our world. When we say we throw things “away” what we mean is out of sight. [11]

Seaweed as a Biofuel

Seaweed has enormous potential to be used as a biofuel. Researchers in Norway have been able to refine kelp into bio-oil yields of up to 79%.

“While petroleum oil is produced naturally on a geologic time scale, we can do it in minutes.”

Khanh-Quang Tran, Norwegian University of Science and Technology (NTNU) Department of Energy and Process Engineering

Biofuel operates on a balance of carbon neutrality. On the one hand, the amount of carbon taken up by the growing plant during its lifetime should offset the emissions of burning. However, the extra space needed to cultivate biofuel crops on land demands drastic land-use changes that may undermine their neutrality. Seaweed is exempt from ticky land use dilemmas and can provide a real carbon-neutral energy source. [12]

In summary, seaweeds have sizeable untapped potential to provide low impact, cheap and scalable solutions to problems arising in this climate crisis.

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