World news – Seaweed, a source of “blue carbon”

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In the overwhelming jungle of climate change studies, one brings not a breath of fresh air but rather fresh water. It looks into seaweed, the only type of forest that does not burn and that has an excellent capacity to store carbon. It also limits the acidification and oxygen depletion of water, as well as mitigating other marine impacts of global warming.
Algaculture is already practised, mainly in Asia, but on a small scale for the food, pharmaceutical and cosmetic industries.
Carried out by marine scientists at the University of Santa Barbara (California, USA), this research quantifies for the first time the global capacity of large-scale algaculture to counterbalance terrestrial sources of carbon emissions, and to map regions suitable for growing seaweed. According to these researchers, growing seaweed over an area representing just 0.001% of the world’s suitable waters and then sequestering it could offset all the carbon emissions of an industrial sector such as aquaculture, which alone provides half of all marine food.

There has been a mixed reaction by scientists to the study, some playing down its findings and others supporting them. While they recall that we do not yet have the technology to contain algae in the ocean depths, they consider that there are more effective methods and that the potential of seaweed is actually greater than the study’s estimations. Supporters claim that, in addition to the capacities already named, seaweed absorbs excess nutrients, provides a habitat for marine life and can be transformed into biofuel or take the place of petroleum-based agricultural fertilizers. When added to cattle feed, algae could also reduce the volume of methane produced during the rumination process by 70% (methane being a powerful greenhouse gas).

So why isn’t algaculture more widespread? According to researchers, if the goal is only to capture and store carbon, it is not currently profitable. There has to be a catalyser to match demand and supply, as well as regulatory environments that facilitate the concessions and licences needed to develop algaculture.

For more information:
Seaweed ‘forests’ can help fight climate change – National Geographic, 5 September 2019

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