ODEON · Online DEposition over OceaNs: Modeling the effect of air pollution on ocean bio-geochemistry in an Earth System Model

Online DEposition over OceaNs: Modeling the effect of air pollution on ocean bio-geochemistryin an Earth System Model

Oceans play an essential role in the adjustment of climate by absorbing part of the emitted CO2 (roughly 30%) from human activities (i.e., fossil-fuel burning, cement production, and land-use change), through the marine ecology and biogeochemistry. Indeed, ocean ecosystems keep CO2 concentrations about 150-200 ppmv lower that would have been without marine phytoplankton. The ocean sequestration of CO2 by biological processes (the biological pump) is directly linked however to the marine productivity and the biomass resources, helping sustain life on our planet. The surface ocean ecosystem comprises, thus, sources and sinks of atmospheric carbon into the deep ocean, with its functioning being controlled by the micro- and macro-nutrients availability which significantly impacted by the atmospheric deposition. Iron (Fe) is a key element for marine life and is required for photosynthesis and respiration. Micronutrient Fe delivered via atmospheric pathways may influence the primary and export production of carbon over the high-nutrient low-chlorophyll (HNLC) oceanic regions (i.e., the oceanic regions where Fe is the limiting factor for phytoplankton productivity). An understanding of the impact of Fe on global marine productivity requires a knowledge of the rates and locations of Fe supply to the ocean, and of the physicochemical forms of Fe that can be utilized by marine biota (i.e., those that are bioavailable). Note, that atmospheric deposition, and in particular that of dust particles, is highly episodic and the annual/monthly time-resolution fluxes of nutrient deposition usually used in state-of-the-art models cannot capture the observed episodic transport. The atmospheric deposition of nutrients may be thus delocalized compared to its impact, since even a non-growth- limiting nutrient deposited over the surface ocean, they may be transported at long distances before directly impacting productivity. The overall objective of ODEON was to address the long-standing shortcoming regarding the global air-quality effect on marine limitations and the ocean carbon cycle, by performing state-of-the-art atmosphere-ocean climate simulations. The main goal of the ODEON project was, eventually, to remedy the aforementioned uncertainties concerning the effects of air-quality and episodic dust deposition into the global ocean using the state-of-the-art ESM.

Data: CORDIS, © European Union