Estimates of human influence on North Sea sedimentary carbon - Current impacts and future scenarios

There is ongoing debate on the influence of human activities on the marine carbon cycle, their potential impacts on climate and resulting implications for marine spatial management. In order to gauge the efficacy of different management options, we estimate the contributions of three direct human impacts on particulate organic carbon in the North Sea: material dumping, marine aggregate mining and bottom trawling. While dumping and mining are considered in a budgetary manner based on existing data, the impacts of bottom trawling are simulated using a high-resolution 3D ocean and sediment models. Several future scenarios of fishing closures and redistribution of effort are considered and their potential climate impacts discussed. Our results indicate that the impacts of sand mining are negligible, while both material dumping and bottom trawling can alter the sequestration capacity of carbon in the North Sea significantly. In the case of bottom trawling, we show that through targeted design of fishing closure zones, the impacts could be greatly reduced without the need to change the overall trawling effort.