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Dryad

Large global variations in the carbon dioxide removal potential of seaweed farming due to biophysical constraints

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Apr 10, 2023 version files 64.50 GB
Feb 06, 2024 version files 64.50 GB

Abstract

Estimates suggest that over 4 gigatons per year of carbon dioxide (Gt-CO2/year) be removed from the atmosphere by 2050 to meet international climate goals. One strategy for carbon dioxide removal is seaweed farming, however, its global potential remains highly uncertain. Here, we apply a dynamic seaweed growth model that includes growth-limiting mechanisms, such as nitrate supply, to estimate the global potential yield of four types of seaweed. We estimate that harvesting 1 Gt/year of seaweed carbon would require farming over 1 million km2 of the most productive exclusive economic zones, located in the equatorial Pacific. We estimate cultivation area would need to be tripled to attain an additional 1 Gt/year of harvested carbon, indicating dramatic reductions in carbon harvest efficiency beyond the most productive waters. Improving the accuracy of annual harvest yield estimates requires better understanding of biophysical constraints and seaweed loss rates, such as disease, grazing, and wave erosion.