Interactive comment on “MEDUSA: a new intermediate complexity plankton ecosystem model for the global domain” by A. Yool et al.

A comment on the paper "MEDUSA: a new intermediate complexity plankton ecosystem model for the global domain” by A. Yool et al. is made

Interactive comment on “Improved routines to model the ocean carbonate system: mocsy 1.0” by J. C. Orr and J.-M Epitalon

The manuscript "Improved routines to model the ocean carbonate system: mocsy 1.0" by J. C. Orr and J.-M Epitalon is reviewed and related issues and ideas are discussed

The role of continental weathering in controlling atmospheric CO2 levels at glacial-interglacial time scales

The potential role of silicate weathering changes for explaining glacial-interglacial variations of CO2 in the atmosphere is discussed. Various methods for reconstructing the evolution of silicate weathering rates on glacial-interglacial time scales are presented. An extensive list of key references and reading materials is provided

Interactive comment on “LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model” by R. E. Zeebe

The paper "LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model” by R. E. Zeebe is reviewed

Interactive comment on “Bottom RedOx Model (BROM, v.1.0): a coupled benthic-pelagic model for simulation of seasonal anoxia and its impact” by E. V. Yakushev et al.

The paper "Bottom RedOx Model (BROM, v.1.0): a coupled benthic-pelagic model for simulation of seasonal anoxia and its impact” by E. V. Yakushev et al. is discussed and reviewed

Model of Early Diagenesis in the Upper Sediment with Adaptable complexity – MEDUSA (v. 2): a time-dependent biogeochemical sediment module for Earth system models, process analysis and teaching

peer reviewedMEDUSA is a time-dependent one-dimensional numerical model of coupled early diagenetic processes in the surface sea-floor sediment. In the vertical, the sediment is subdivided into two different zones. Solids (biogenic, mineral, etc.) raining down from the surface of the ocean are collected by the reactive mixed layer at the top. This is where chemical reactions take place. Solids are transported by bioturbation and advection, and solutes are transported by diffusion and bioirrigation. The classical coupled time-dependent early diagenesis equations (advection–diffusion reaction equations) are used to describe the evolutions of the solid and solute components here. Solids that get transported deeper than the bottom boundary of the reactive mixed layer enter the second zone underneath, where reactions and mixing are neglected. Gradually, as solid material gets transferred here from the overlying reactive layer, it is buried and preserved in a stack of layers that make up a synthetic sediment core. MEDUSA has been extensively modified since its first release from 2007. The composition of the two phases, the processes (chemical reactions) and chemical equilibria between solutes are not fixed any more, but get assembled from a set of XML-based description files that are processed by a code generator to produce the required Fortran code. 1D, 2D and 2D×2D interfaces have been introduced to facilitate the coupling to common grid configurations and material compositions used in biogeochemical models. MEDUSA can also be run in parallel computing environments using the Message Passing Interface (MPI).SERENAT

Atmospheric CO2 consumption by continental erosion : present-day controls and implications for the last glacial maximum

The export of carbon from land to sea by rivers represents a major link in the global carbon cycle. For all principal carbon forms, the main factors that control the present-day fluxes at the global scale have been determined in order to establish global budgets and to predict regional fluxes. Dissolved organic carbon fluxes are mainly related to drainage intensity, basin slope, and the amount of carbon stored in soils. Particulate organic carbon fluxes are calculated as a function of sediment yields and of drainage intensity. The consumption of atmospheric/soil CO2 by chemical rock weathering depends mainly on the rock type and on the drainage intensity. Our empirical models yield a total of 0.721 Gt of carbon (Gt C) that is exported from the continents to the oceans each year. From this figure, 0.096 Gt C come from carbonate mineral dissolution and the remaining 0.625 Gt C stem from the atmosphere (FCO2). Of this atmospheric carbon, 33% is discharged as dissolved organic carbon, 30% as particulate organic carbon, and 37% as bicarbonate ions. Predicted inorganic carbon fluxes were further compared with observed fluxes for a set of 35 major world rivers, and possible additional climatic effects on the consumption of atmospheric CO2 by rock weathering were investigated in these river basins. Finally, we discuss the implications of our results for the river carbon fluxes and the role of continental erosion in the global carbon cycle during the last glacial maximum

Modelled interglacial carbon cycle dynamics during the Holocene, the Eemian and Marine Isotope Stage (MIS) 11

peer reviewedTrends in the atmospheric concentration of CO2 during three recent interglacials – the Holocene, the Eemian and Marine Isotope Stage (MIS) 11 – are investigated using an earth system model of intermediate complexity, which we extended with process-based modules to consider two slow carbon cycle processes – peat accumulation and shallow-water CaCO3 sedimentation (coral reef formation). For all three interglacials, model simulations considering peat accumulation and shallow-water CaCO3 sedimentation substantially improve the agreement between model results and ice core CO2 reconstructions in comparison to a carbon cycle set-up neglecting these processes. This enables us to model the trends in atmospheric CO2, with modelled trends similar to the ice core data, forcing the model only with orbital and sea level changes. During the Holocene, anthropogenic CO2 emissions are required to match the observed rise in atmospheric CO2 after 3 ka BP but are not relevant before this time. Our model experiments show a considerable improvement in the modelled CO2 trends by the inclusion of the slow carbon cycle processes, allowing us to explain the CO2 evolution during the Holocene and two recent interglacials consistently using an identical model set-up

Modelling of the Marine Carbon Cycle

The lecture is subdivided into two parts. The first one deals with the essence of modelling, with the main principles and stages of development. The procedure of model development will be exemplified on the basis of a practical question. During this first part, a number of concepts and parameters that are important for the particular case of ocean carbon cycle modelling are already introduced. In the second part, we further deepen these. We explore the main physical and biogeochemical processes that are important to understand how the carbon cycle operates in the world ocean and provide insight into the way they are represented in different types of models currently used

Comment on gmd-2020-405

The paper "A model for marine sedimentary carbonate diagenesis and paleoclimate proxy signal tracking: IMP v0.9" is discussed and reviewed