Co-benefits of carbon sink and low carbon food supply via shellfish and algae farming in China from 2003 to 2020

Innovative strategies for effective carbon emission reduction play an important role to limit global warming to less than 1.5 °C. Mariculture of shellfish and algae has double benefits of obtaining food with a low-carbon footprint and sequestrating carbon during the natural process. This work estimated the co-benefits of low carbon food supply and carbon sequestration via shellfish and algae farming in China. Spatiotemporal evolution, driving factors, and decoupling status of shellfish and algae farming from 2003 to 2020 were comprehensively analyzed. Results showed that approximately 6.0 Mt CO2-eq yr−1 were sequestrated in China from 2003 to 2020 via shellfish and algae farming. Shellfish farming could reduce carbon emissions by 31.7 Mt CO2-eq yr−1 by providing 0.39 Mt yr−1 of highly-quality protein when compared to beef production. Moreover, algae farming could reduce the carbon emissions of 0.7 Mt CO2-eq yr−1 by providing 1.6 Mt yr−1 edible food (vegetable) when compared to beet production. The increasing marine fishery economy and farming capacity are the main driving factors for the continuously improving CO2 sequestration capacity of shellfish and algae during 2003–2020. These two driving factors increased carbon sink by 10.35 Mt CO2-eq from 2003 to 2020 accordingly. However, farming area efficiency had a mainly negative effect on the carbon sink with a total 6.94 Mt CO2-eq reduction. In general, China's shellfish and algae farming values account for only a small proportion of the marine fishery value, requiring robust incentive strategies, such as government subsidies and blue carbon trading, to improve carbon sink capacity in China.