On September 24, 2025, around 30 scientists from various institutions met at the German Climate Computing Center (DKRZ) in Hamburg for the natESM Focus Workshop on Ocean Biogeochemistry (OBGC). The aim of the meeting was to bring together, for the first time, the wide range of OBGC models, modules, and methodological approaches in Germany — and to explore ways toward a more coordinated and collaborative development effort.
The workshop was opened by Jochem Marotzke (Max Planck Institute for Meteorology, natESM Co-Chair), who emphasized its significance within the framework of the national Earth system modeling strategy (natESM). The goal, he noted, was to understand the diversity of existing approaches, identify shared development perspectives, and strengthen synergies across the various components of the natESM system.
The morning session provided a broad overview of current modeling approaches – from REcoM, HAMOCC, and ECOSMO to OPEM – illustrating that the diversity of concepts and levels of complexity is both a major strength and a challenge for integration and collaboration. A key topic of discussion was the Framework for Aquatic Biogeochemical Models (FABM), which was seen as a potential bridge between different hydrodynamic and biogeochemical models.
As the day unfolded, it became clear how valuable this workshop was in initiating a shared process of understanding. When we raised the question of a sustainable, community-oriented development strategy – How can we bring these forces together? – it prompted a moment of reflection and marked the beginning of a new way of thinking: toward an open and collaborative development culture (open development) in ocean biogeochemistry.
As a result of the workshop, Judith Hauck (AWI) and Carsten Lemmen (Hereon) agreed, in coordination with Iris Ehlert (natESM Process Coordinator, DKRZ), to initiate the establishment of a new Ocean Biogeochemistry Working Group. This group will be launched in the coming weeks and will serve as a platform to define interfaces, integration strategies, and shared development goals.
Since the next natESM Community Workshop coincides with the Ocean Sciences Meeting 2026, another focus workshop is planned for the coming year to continue and deepen the exchange initiated in Hamburg.
Welcome and introduction
- Jochem Marotzke (MPI-M, natESM Co-Chair): Welcome and short input on natESM and purpose of the workshop
Community presentations – Ocean Biogeochemistry Modeling
- Judith Hauck (AWI): Regulated Ecosystem Model (REcoM): Recent advances and plans ahead
- Tatiana Ilyina (UHH/MPI-M): Ocean Biogeochemistry in the ICON Framework: Challenges and Opportunities
- Kai Logemann (Hereon): ECOSMO and ECOSMO_E2E: Perspectives and integration challenges
- Andreas Oschlies (GEOMAR): OPEM: Optimality-based non-Redfield Plankton-Ecosystem Model, overview and recent developments
- Nicolas Gruber (ETH Zürich): Why we need more "bio" in high-resolution biogeochemistry modeling
Open discussion - Integration pathways in natESM
- Wilton Jaciel Loch (DKRZ): Overview of technical integration pathways and interface requirements in natESM
