How seaweed can help tackle the climate crisis

As well as being an important habitat for marine life, the humble seaweed helps to regulate our climate and absorb carbon from the atmosphere.

Charlotte Cameron
Seaweed ocean climate change seaforestation
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Did you know that every second breath we take is thanks to the ocean? It’s our planet’s life support system and we need it to survive.  

It’s a source of food for people all around the world, home to an abundance of life and it also helps regulate our climate. Seaweed, the name given to thousands of species of marine algae and plants, plays a critical role in this precious underwater ecosystem.  

On World Oceans Day we are looking at why seaweed is so important and how we can use it to help solve one of the biggest challenges we face. 

How seaweed helps

This humble weed provides a multitude of benefits, extending well beyond being an important habitat for marine life.  

For thousands of years, it has been a source of food, animal feed and fertiliser. Often referred to as a “miracle plant”, seaweed is rich in nutrients like vitamin K and fibre, making edible seaweed a superfood that is growing in popularity.  

Seaweed can also help stop coastal erosion and act as a breakwater during storms, as water slows down as it travels through it.  

Critically, marine algae help to regulate our climate. Kelp forests, made up of certain types of seaweed, are pound for pound among the most productive ecosystems on the planet; absorbing more carbon from the atmosphere than any other habitat. In fact, the ocean holds fifty times more carbon than the atmosphere. Seaweed is thought to sequester nearly 200 million tonnes of CO2 every year – as much as New York State’s annual emissions

Seaweed can act as a buffer against ocean acidification. Because CO₂ has an acidifying effect on seawater, as the kelp absorb the CO₂, the water becomes less acidic. 

It can also be used as a plastic alternative to create bio-packaging. This alternative could reduce the nearly eight million metric tonnes of single-use plastic thrown into the ocean annually. 

Current state of ecosystem

Kelp forests are disappearing around the world, with one study finding that since the 1960s, there has been a decline in more than a third of kelp forests. In Northern California, 95% of kelp forests have died off in the last eight years alone.  

Causes of decline range from local issues like population growth of sea urchins and pollution, to global impacts such as climate change. Rising sea temperatures and the effects of climate change have seen Western Australia, for example, lose 43% of its kelp in 2011.  


Studies show that just a 0.5% change in the amount of carbon contained in the oceans could solve the climate crisis. This could be done through seaforestation, which would deliver a wealth of benefits to people and oceans. Seaforestation is a process of seeding fast-growing seaweed like kelp. This can help to not only boost marine life and benefit coral reefs but to also sequester more carbon from our atmosphere.  

There are three methods of achieving this currently being explored by different organisations, all starting with seaweed being grown on ropes between buoys. One approach allows these farms to be moved into “marine deserts” – huge areas of the ocean that are nutrient depleted. Irrigation systems pump cold, nutrient-rich water into these areas to provide the conditions that kelp need to thrive.  

Another approach brings the kelp farm to deep water using submersible drones, alternating between sunlight near the surface during the day and then moving to the more nutrient-rich waters at night.  

The other technique involves biodegradable buoys to allow farms to be grown near shore before the currents carry them out to deep ocean where the buoys will biodegrade, and the kelp will sink.  

These methods to “rewild” our ocean floor will help restore and expand critical seaweed ecosystems that can boost marine life, reverse ocean acidification and safely sequester carbon among a multitude of other benefits.  

Here are five ways that you can support our oceans:  

– Learn about where and why wild kelp forests are disappearing so you can support their restoration 

– Avoid single-use plastics 

– Sign up and speak out: become an advocate for the ocean through your networks and local community  

– Vote on ocean issues 

– Reduce your carbon footprint to prevent ocean acidification  


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