|What do we do? - Science|
WP 11 leader: Marion Gehlen (marion.gehlen (at) lsce.ipsl.fr) CEA
- Determine the impacts of ocean acidification on carbon and other key element cycles as well as climate relevant gases from the regional to the global scale (CO2, DMS, N2O).
- Assess the impact of emission scenarios on simulated ecosystem structure and function.
- Quantify the changing role of marine sediments as sinks and sources of macro- and micro-nutrients (P, Fe) under future ocean acidification and climate change scenarios and investigate the impact of these changes on shelf and open ocean ecosystems and biogeochemistry.
- Assess the potential of different long-term observation approaches (radionuclides, alkalinity changes, sediment traps) for detecting impacts due to ocean acidification.
Description of work and role of participants:
Use a hierarchy of regional (PML, AWI, ETH ZURICH, UU) to global (MPG, CEA, UiB, UBern) biogeochemical-ecosystem models, some of which include not only the water column but also couple that to an interactive benthic compartment (PML for benthic biogeochemistry and ecology; CEA, UiB, MPG, UU, UBern for benthic biogeochemistry), to address three tasks:
T10.1: Model Development: to incorporate new process knowledge and parameterisations from WP9 in order to better evaluate how ocean acidification affects individual processes and improve 3-D ocean biogeochemical and ecosystem models (All partners).
T10.2: Model Performance Assessment: to evaluate the capability of models to reproduce existing and new datasets of dissolved properties (e.g., carbonate system parameters [WP10], O2, nutrients); and to exploit new data for the biogeography of calcifying organisms from WP3 (All partners]. Model output will be compared to relevant data, particularly where model domains overlap (e.g. the North West African upwelling system) (AWI, ETH ZURICH).
T10.3: Model-based assessment of impacts of ocean acidification on key biogeochemical and ecosystem processes, including sediment biogeochemistry: Efforts will focus on (i) the photic zone (ecosystem structure and productivity, stoichiometry of C fixation and export production, CaCO3 production, global fluxes of climate relevant gases, changes in bioavailability of macro-and micro-nutrients including sediment biogeochemistry in shelf areas) and (ii) the aphotic zone (remineralization of organic carbon, particle aggregation and ballasting, CaCO3 dissolution, and the rain ratio). The relative importance of physical versus biological-biogeochemical processes and their uncertainties will be identified by using sensitivity studies and probabilistic approaches (All partners).