The human population is projected to rise from 7 billion today to close to 10 billion by 2050. Providing food to this many people will be one of the greatest challenges of the 21st century. Due to competing interests in land use from various societal sectors, the potential for expanding farmland is limited. This turns the focus on the ocean, which covers more than two thirds of our Earth’s surface. However, marine fish stocks for the most part are already fully exploited or even over-exploited. And even aquaculture, the fastest growing food sector worldwide, requires animal feed, either from wild fish or land farming. Ocean artificial upwelling could help increase marine productivity and raise fish production. If powered by renewable energy, this could be achieved at a low carbon footprint. In contrast to the high water demand of livestock production on land, it would come free of freshwater usage, and by tapping into the huge deep ocean nutrient reservoir, it would be independent of crop fertilizers. If applied off-shore out of range of shipping routes and fishing grounds, there would be no competing interests for space.
The productivity of the ocean is limited by the transport of nutrient-rich deep waters to the sun-lit surface layer. In large parts of the global ocean this transport is blocked by a temperature-induced density gradient, with warm light waters residing on top of heavier cold waters. These regions, which are referred to by scientists as ocean deserts, are presently expanding due to global warming. Enhancing the upward transport of nutrient-rich deep waters through artificial upwelling can break this blockade and make these waters more productive. To what extent this raises fish production and whether it can strengthen oceanic CO2 sequestration is still an open question. Importantly, the potential risks and side effects of this approach are largely unknown.
Ocean artUp aims to study the feasibility and effectiveness of artificial upwelling in fertilizing ocean productivity and enhancing energy transfer to higher trophic levels with the potential of raising fish production. Ocean artUp further investigates the impacts of artificial upwelling on biogeochemical cycling, including carbon export potential, and air-sea gas exchange of climate relevant gases. A particular emphasis is laid on elucidating the associated risks and potential side effects in terms of changing ocean ecosystems structure and functioning and modifying nutrient inventories and fluxes.
