(Ivy Frenger, Wolfgang Koeve)

The ocean contributes to the uptake of about 25% of historical and current anthropogenic CO₂-emissions, thus mitigating climate change. The current marine CO₂ uptake is strongly dominated by physical-chemical processes while the biological carbon ‘pumps’, by way of that isolatinge carbon from exchange with the atmosphere in the ocean interior, are known to be of highgreat relevance on long, multi-millennial timescales. This group seeks to improve the understanding of the relative role and sensitivity to climate change of marine carbon storage, and in particular the relative role of the biological pumps on timescales varying from centennial to interglacial. We use ocean circulation and Earth System models (e.g. UVic, TMM, FOCI), in combination with novel idealized tracer approaches. We further contribute to international activities to (i) diagnose and review the current status and possible future changes of the biological carbon pumps and (ii) improve the quantification of their role in climate. 

Contributors:

• Ivy Frenger: (role of physics therein, in particular also features that are subgrid scale in global Earth system models such as mesoscale eddies)
• Wolfgang Koeve: (UVic model development (separation techniques), experiments & publications on quantification of marine carbon pumps and the attribution of their feedback potential to atmospheric pCO₂ and Earth climate under Holocene and Anthropocene conditions; POF IV Subtopic 6.3 GEOMAR co-speaker [since Dez 2022];  contributor to JETZON Biological carbon pump review project [WG4,  biogeochemical constraint])
• Malte Jürchott: (enhancement of biological carbon pump in the context of the marine CDR method “artificial upwelling”; Ph.D. student in Test-ArtUp, WP4)
• Iris Kriest: (co-chair of SCOR WG 161 ReMO: Respiration in the Mesopelagic Ocean; WP lead of EU Project OceanICU; testing sensitivities of global BGC model properties to parameterisations of particle flux length scales; global model assessment and calibration against various observations, among them sediment traps )
• Markus Schartau: (analyses of size spectra of i. carbon- and nitrogen enriched marine microgels and ii. of marine particle aggregates; spatio-temporal variations of the organic content of suspended particulate matter, SPM) 
• Tianfei Xue: Relationship of export/export efficiency to physics-driven plankton dynamics 
• Haichao Guo: Evaluation of methods to estimate respiration rates and their changes