Paper Blue Growth Potential to Mitigate Climate Change through Seaweed Offsetting

video about seaweed

Seaweed offsetting is not the sole solution to climate change, but it provides an invaluable new tool for a more sustainable future.

Carbon offsetting - receiving credit for reducing, avoiding, or sequestering carbon - has become part of the portfolio of solutions to mitigate carbon emissions, and thus climate change, through policy and voluntary markets, primarily by land-based re- or afforestation and preservation. However, land is limiting, creating interest in a rapidly growing aquatic farming sector of seaweed aquaculture.

Synthesizing data from scientific literature, we assess the extent and cost of scaling seaweed aquaculture to provide sufficient CO2eq sequestration for several climate change mitigation scenarios, with a focus on the food sector - a major source of greenhouse gases. Given known ecological constraints (nutrients and temperature), the authors of the paper found a substantial suitable area (ca. 48 million km 2) for seaweed farming, which is largely unfarmed. Within its own industry, seaweed could create a carbon-neutral aquaculture sector with just 14% (mean = 25%) of current seaweed production (0.001% of suitable area). At a much larger scale, the authors find seaweed culturing extremely unlikely to offset global agriculture, in part due to production growth and cost constraints. Yet offsetting agriculture appears more feasible at a regional level, especially areas with strong climate policy, such as California (0.065% of suitable area). Importantly, seaweed farming can provide other benefits to coastlines affected by eutrophic, hypoxic, and/or acidic conditions, creating opportunities for seaweed farming to act as “charismatic carbon” that serves multiple purposes.


  • Ca. 48 million km 2 of the oceans are suitable for seaweed aquaculture (SA)
  • Offsetting the aquaculture sector requires 14%–25% of current farmed seaweeds
  • Production scale and cost are too limiting to sequester global agricultural CO 2eq
  • SA could help buffer eutrophic, hypoxic, or acidic waters in at least 77 countries


Status 22.10.2019

Banner picture copy right Juris Aigars, LHEI


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