Climate benefits of seaweed farming: estimating regional carbon emission and sequestration pathways

Seaweed farming is widely promoted as an approach to mitigating climate change despite limited data on carbon removal pathways and uncertainty around benefits and risks at operational scales. We explored the feasibility of seaweed farms to contribute to atmospheric CO2 reduction in coastal British Columbia, Canada, a region identified as highly suitable for seaweed farming. Using a place-based, quantitative model, we examined five scenarios spanning a range of industry development. Our intermediate growth scenario sequestered or avoided 0.20 Tg CO2e / year, while our most ambitious scenario (with more cultivation and higher production rates) yielded a reduction of 8.2 Tg CO2e /year, equivalent to 0.3% and 13% of annual greenhouse gas emissions in BC, respectively. Across all scenarios, climate benefits depended on seaweed-based products replacing more emissions-intensive products. Marine sequestration was relatively inefficient in comparison, although production rates and avoided emissions are key uncertainties prioritized for future research. Our results show how seaweed farming could contribute to Canadas climate goals, and our model illustrates how farmers, regulators, and researchers could accurately quantify the climate benefits of seaweed farming in local contexts.