Carbon sinks: sequestering carbon through biomaterials

Regenerative economy

Carbon sinks: sequestering carbon through biomaterials

Various parts of the world are experiencing scorching heat and extreme weather events. In Algeria, for instance, temperatures reached 57°C, while Greece reeled from wildfires around the country speculated to be caused, in part, by the unprecedented heat the city continues to experience. Rising temperatures and the increased frequency of extreme weather events can be attributed to potent greenhouse gases (GHGs). Concentrations of carbon dioxide (CO2), the most abundant GHG, continue to rise, causing unpredictable feedback and thrusting the stressed planet into unfamiliar territory.

CO2 emissions from fossil fuels and industry continue to skyrocket. (Source: OECD)CO2 emissions from fossil fuels and industry continue to skyrocket. (Source: OECD)

It is becoming increasingly clear that while emissions need to end faster than current commitments promise, efforts to absorb existing GHGs from the atmosphere need to expand exponentially.

What can the world turn to sequester CO2 emissions, and what role do biomaterials play in accelerating global carbon sequestration efforts?

What is sequestration exactly?

Carbon, in various forms, cycles through the atmosphere, the ground, the water, fossils, and living organisms. While the presence of CO2 in the atmosphere is normal, our incessant use of fossil fuels, along with changes in land use, has increased our emissions, and consequently CO2 concentrations, to unprecedented levels.

Carbon sinks can be anything that absorbs CO2 and ‘stores’ it, which is to say, that they absorb more CO2 than they release. Sequestration is merely the process of storing, and not merely absorbing, carbon by a biotic or abiotic entity.

The ocean, for instance, is one of the biggest natural carbon sinks, and sequesters close to 50% of the world’s CO2. Various ecosystems like rich rainforests and peatlands are precious carbon sinks that continue to be lost to land use changes, and ecological destruction. The Amazon rainforest, one of the planet’s biggest and most reliable carbon sinks, produced more carbon dioxide than it absorbed in 2018 due to deforestation and forest fires.

Reducing CO2 emissions and concentrations is extremely important to reduce global temperature rise and other positive feedbacks. But this herculean task requires scientific knowledge and innovation because even if we stopped emitting CO2 today, “it would take many thousands of years for atmospheric CO2 to return to “pre-industrial” levels due to its very slow transfer to the deep ocean and ultimate burial in ocean sediments”.

Bringing CO2 concentrations to pre-industrial levels through novel solutions will take all our knowledge, especially indigenous, creativity, and imagination. We need to preserve existing carbon sinks, but we also need to urgently study and explore natural biomaterials that can help bring down emissions to safe levels.

"The power of carbon sequestration lies not only in reducing greenhouse gas levels but also in empowering communities to protect their environment and livelihoods." -- Christiana Figueres

Sequestration: the magic of nature

Below are a few of the many highly versatile biomaterials that have astounding carbon sequestration capabilities and can bring us closer to our vision of a regenerative world.

Azolla fern

The “carbon dioxide hungry” Azolla fern has a fascinating history. Around 50 million years ago, there was a spike in CO2 particles in the atmosphere, which was “dangerously overheated” by GHGs. In various cycles lasting a million or so years, it sequestered over half of that CO2, bringing back CO2 levels down.

Could it perhaps help us do the same today? A hectare of Azolla can produce roughly twenty tons of bio-oil and fifty-eight tons of biochar per year! Azolla can also be used as an efficient fertilizer, and in human nutritional supplements!

Azolla fern had a fascinating history dating back 50 million years ago (Source: Wikipedia)Azolla fern had a fascinating history dating back 50 million years ago (Source: Wikipedia)


There exist about 60 species of seagrass, which are the only flowering plants that grow in marine environments! Not only is seagrass important for marine biodiversity, they play a crucial role in regulating oceanic currents. Moreover, seagrass’ sequestration capabilities are immense!

A hectare of seagrass can sequester as much carbon as 10-40 hectares of dry forests! Seagrass is used in some medicines, food, fertilisers, and other industrial materials. Mondoro is a company that makes fascinating home decor products out of seagrass!


Most of us might be familiar with cork. It is widely used in packaging or in seals for wine bottles. Corks are made from the bark of cork oak trees, which do not need to be cut for cork production. This means that the tree can continue accruing carbon for the 200 or so years that it lives.

This has incredible implications for the cork to store carbon within. Industry experts believe that each cork stopped could sequester up to 400 g of carbon! Mahi Leather makes wonderful bags and accessories using vegan leather made out of cork barks.

Cork extraction - only the barks are extracted, the tree does not need to be cut down (Source: Wikipedia)Cork extraction - only the barks are extracted, the tree does not need to be cut down (Source: Wikipedia)


Bamboo is a naturally occurring tree, which has incredible carbon sequestration capabilities. Researchers estimate that about 1 hectare of bamboo can absorb up to 17 tonnes of CO2 every year.

Fun fact: Bamboo occurs in many everyday products used by roughly 2 billion people!

💡Check out our selection of the best companies using bamboo to make fabrics, cutlery, packaging here!


Seaweeds are plant-like organisms, with about 10,00 species, that are found only in the sea (as opposed to algae which can be found in any water body). They are crucial for marine biodiversity, and are increasingly being explored for their ability to provide low-carbon food for human and animal consumption.

Some estimates suggest that cultivated seaweed can sequester 57.64 tons of CO2 per hectare per year (for reference, a forest in general absorbs 1.1 tons of CO2 per hectare per year)

💡Check out our selection of the best companies making bio-inks, packaging, and various other industrial materials from seaweed here!

Mycorrhiza and Fungi

Mycorrhizal connections are crucial in the plant world because they manage to break down the CO2 trees absorb into minerals and resources ecosystems can thrive on. It is also believed that Mycorrhiza helps keep carbon under the ground for longer periods of time, thereby reducing the potency of atmospheric CO2.

Fungi are widely used globally for food, and are also used to make Chitosan - another useful biomaterial. Chile was the first country to add the fungal kingdom to its environmental protection! Ecovative uses mycelium to produce everything from leather to beauty, to construction components.


Hemp is a plant grown widely for its bast (stem) fibres which have varied uses, textiles, oils, feed, and farmaceuticals being a few of them. Hemp is critically understudied, but some research estimates suggest that hemp is almost twice as effective at capturing atmospheric carbon than trees. 1 hectare of hemp can sequester anywhere from 8-22 tonnes of CO2 a year.

Fun fact: France, by a long margin, is the leader of hemp cultivation in Europe, second only to China in the world!

Final thoughts

As is true for all things, the use of natural biomaterials must be thoughtful, and ecologically sound.

The Azolla fern, for instance, is an invasive species. Its ability to expand rapidly, even in the presence of environmental stresses, can make it an uncontrollable ecological threat.

Bamboo’s invasiveness in ecologically sensitive areas, is also important to monitor. We cannot replace biodiverse forests with bamboo, or any other biomaterial for that matter, to meet our textile, food, and material needs.

Addressing our material needs through regenerative principles will necessarily require using native varieties, and biomaterials found locally because they are well adapted to those ecosystems and offer a chance to promote endemic biodiversity.

This list is by no means exhaustive. If anything, it just serves to remind us that our efforts to reduce CO2 emissions don’t need to rely on heavy and expensive technology alone. Hope and belief continue to drive the discovery of such biomaterials and the innovation of many others.

💡 Download our Biomaterials A-Z to deep dive into the world of low-carbon and regenerative materials here!

Written by Dewansh M. on 14/08/2023

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