Blue carbon in an eastern boundary upwelling zone – A case study in Namibia

Abstract

Blue Carbon (BC) refers to Nature-Based Solutions in marine environments that aim to reduce greenhouse gases through carbon sequestration using natural processes. Much of the BC focus to date has been on tropical coastal habitats, especially salt marshes, mangroves, and seagrass beds, while research in temperate marine environments has lagged. In this paper, we investigate the BC potential in a cold-temperate eastern-boundary upwelling ecosystem, the northern Benguela off Namibia. We identified four areas, where the BC concept can be applied, identify data gaps and areas for future research. 1) Macroalgae play a large role in carbon sequestration globally, although many of the values and specifics remain debated. We recommend research to investigate the ultimate flows, fate and permanence of carbon in Namibian kelp forests, and the development of a high-quality national map of kelp biomass distribution. 2) The northern Benguela has a high abundance of gelatinous plankton, possibly associated with the collapse of the small pelagic fish stocks. Gelatinous plankton play an important role in the global carbon cycle and research into their role in carbon flow and sequestration in the northern Benguela is recommended. 3) Commercial fisheries are amongst the highest producers of carbon globally. We strongly support policies that promote the restoration of Namibian fish stocks, especially sardine and recommend undertaking analyses of the carbon-footprint of Namibian fisheries and their supply chains to identify areas where carbon production could be reduced through improved efficiency, reduced impact on the seabed and optimised transport solutions. 4) Namibia hosts some of the world's most carbon-rich marine sediments along its continental shelf. We recommend conducting a BC natural capital assessment of the environmental and financial value of these sediments and any impacts thereon. These actions could open new markets for Namibian products that prioritise low-carbon foodstuffs. Combined, a more thorough assessment of Namibia's BC ecosystems could contribute substantially to Namibia's nationally determined contributions.