The crisis posed by climate change has drawn the attention of governments, businesses, and society to increase the efforts to reduce greenhouse gas (GHG) emissions. However, the challenge of keeping the increase of global temperature below 1.5ºC of pre-industrial conditions requires not only cutting emissions but also coming up with new ways of capturing and storing atmospheric CO2. While innovation and technology play a role in carbon sequestration, international consensus points at nature-based solutions as the most effective approaches1.
All inland ecosystems combined cannot store all the necessary carbon to achieve this goal, thus the attention to oceanic alternatives has increased. Coastal habitats such as mangroves, seagrass, and marshes are well-known dynamos for carbon capture, with many ecological and socioeconomic services strengthening their role in climate change mitigation and adaptation strategies. However, while the spotlight has been pointing at the coasts, the role of other offshore ecosystems, such as seaweed, has been mistakenly overlooked.
Seaweed represents the most extensive and productive marine habitat globally. Growing in rocky, non-fertile surfaces, it has the potential to capture 173 million metric tons of CO2 per year globally2 with a rate of 50 metric tons or more of CO2 per hectare3,4. This represents several times more sequestration than any other living ecosystem (Figure 1). Yet the benefits of these macroalgae habitats go beyond carbon capture capacity.
Unlike its terrestrial and coastal counterparts, seaweed fixes carbon without the risk of this being released back to the atmosphere due to forest fires and land degradation. About 82% of the carbon captured by seaweed is exported to the open ocean and a significant portion ends up in the deep sea, where the conditions facilitate a low risk of CO2 release and long-term storage5. Seaweed ecosystems also contribute to the deacidification of the ocean, provide shelter to species of economic interest, and protect shores from erosions and natural disasters (reduces wave energy)6. Furthermore, the growing interest in seaweed for commercial purposes (biofuel, food, animal food, medicine, among others) has made it one of the fastest-growing sectors of food production (worth 14,1 billion USD in 2021) with a projected growth of 7,51% between 2021 and 20287.
What does this mean for Belgium?
The EU aims for carbon neutrality by 2050 and the action plans to achieve this includes planting three billion trees by 2030 and preserving 30% of sea areas8. In tune with the regional framework for an inclusive and sustainable economy, the Flemish Government is planning to expand the public natural areas with 10,000 hectares of new forest by 2030 9.
The North Sea is home to wild and farmed seaweed as its rocky sea bottom and cold-temperate water allow the macroalgae to settle and proliferate. Even though the effect of climate change in macroalgae is not yet clear, the conditions of the North Sea can provide an opportunity to include seaweed as an ocean-based solution in local climate adaptation and mitigation strategies10. It is important to mention that seaweed is yet to be considered a carbon sequestration strategy within the Intergovernmental Panel on Climate Change (IPCC) framework due to limited available technology to accurately measure the carbon stored at a particular site.
Interest in seaweed is still growing in the country with the first-ever seaweed aquaculture farm between offshore wind turbines being piloted in Belgium by the Belgian-Dutch consortium Wier & Wind11. This large-scale automated seaweed farm and other smaller initiatives follow the governmental call for the exploration of the multiple uses of the Belgian part of the North Sea (2nd Maritime Spatial Plan (MSP))12. While there are still barriers in policy and technology to overcome, attention to the environmental and economic benefits of seaweed ecosystems will only continue to grow.
Footnotes
- Intergovernmental Panel on Climate Change (2018). Global Warming of 1.5 °C. Available at https://www.ipcc.ch/sr15/
- Krause-Jensen, D. & Duarte, C.M (2016). Substantial role of macroalgae in marine carbon sequestration. Nature Geoscience 9:737-742. Substantial role of macroalgae in marine carbon sequestration | Nature Geoscience
- Lauren, L., M. Lane, & R. Nelson. (2020). Sustainable Seaweed Biotechnology Solutions for Carbon Capture, Composition, and Deconstruction. Trends in biotechnology. https://www.sciencedirect.com/science/article/pii/S0167779920300901
- A Cultivated seaweed carbon sequestration capacity (2019). https://iopscience.iop.org/article/10.1088/1755-1315/370/1/012017/pdf
- Krause-Jense, D, et al. (2018). Sequestration of macroalgal carbon: the elephant in the Blue Carbon room. The Royal Society. https://royalsocietypublishing.org/doi/10.1098/rsbl.2018.0236
- Duarte, C., J. Wu, X, Xiao, Bruhn, A. & D. Krause-Jensen, D.Can Seaweed Farming Play a Role in Climate Change Mitigation and Adaptation? Frontier in Marine Science. https://doi.org/10.3389/fmars.2017.00100
- Fortune business insights. Market Research Report (2021). Commercial seaweed market size, share & COVID-19 impact analysis, by type, forms, end-used and regional forecasts, 2021-2028. https://www.fortunebusinessinsights.com/industry-reports/commercial-seaweed-market-100077
- European Green Deal. European Commission. (2020).
- https://www.bosteller.be/
- Frowhlich, H., J.C Afflerbach, M. Frazier, & B. Halpern. (2019). Blue Growth Potential to Mitigate Climate Change. Current Biology. https://iopscience.iop.org/article/10.1088/1755-1315/370/1/012017/pdf
- Interreg Vlaanderen Nederland - Wier & Wind. https://www.ugent.be/en/research/research-ugent/eu-trackrecord/interreg/wierenwind.htm
- European MSP Platform: Belgium. https://www.msp-platform.eu/countries/belgium
