Climate-Induced Changes in Marine Biogeochemical Cycles and their Impact on Marine Ecosystems

Marine biogeochemistry is being profoundly reshaped by the ongoing processes of climate change, leading to widespread and complex effects on the organisms inhabiting marine systems, the services they provide, and ultimately human society. Multiple stressors, including increasing sea surface temperature, ocean acidification, deoxygenation, and stratification, have combined to alter biogeochemical pathways involving elements such as carbon, nitrogen, phosphorus, sulfur, and micronutrients within the oceans. These alterations affect primary production, nutrient ratios, and the structure of marine food webs at all trophic levels. The current paper aims to investigate the mechanistic couplings of climate-induced forcing and marine biogeochemical processes using multiple-decadal observational data, satellite remote sensing, and published model products from a variety of key oceanic regions: the Arctic Ocean, the Mediterranean Sea, the Baltic Sea, and the open ocean. Focus on the impact of warming and acidification on carbon export efficiency; the role of nitrogen cycle feedbacks on coastal eutrophication and hypoxia, and the effects of changes to the sulfur cycle on climate. Overall, there are significant observed and modeled changes to nutrient flux rates, oxygen profiles and the efficiency of the biological pump throughout the regions analyzed. There is an immediate requirement for integrated biogeochemical monitoring and adaptive management in marine systems to ameliorate the impact of escalating climate change. This study will add to the expanding body of scientific evidence required to inform the urgent implementation of robust ocean governance and conservation policies.