Atmospheric CO2 reconstructions beyond ice core records are based on geochemical proxies, which bear proxy-specific intrinsic uncertainties. Here, we use the global carbon cycle box model BICYCLE-SE and explore possible changes in the carbon cycle during the last 4 Myr in order to improve existing interpretation of proxy-based CO2 reconstructions with focus on δ11B. Simulating the full marine carbon cycle the results can be compared with various variables of interest, and which are necessary within the context of the δ11B-based CO2 proxy. In detail, these are pH, dissolved inorganic carbon, total alkalinity, and pCO2 within the surface equatorial Atlantic or equatorial Pacific, the areas in which the sediment records are located, that are used for atmospheric CO2 reconstructions.In addition, simulated mean ocean δ13C is compared with various available data.The model is forced with changing physical boundary conditions, mainly changes in temperature and sea level, which are taken from a new data compilation. Simulated changes in surface and deep ocean carbonate ion and the depth of the calcite saturation horizons are further model ouput that can be used for evaluation of results. Finally, simulated / assumed solid Earth carbon fluxes (volcanic CO2 outgassing, carbonate and silicate weathering, coral reef growth, carbonate accumulation in the sediment and the net ocean-to-sediment fluxes) are included here.

Archive file (tgz) which includes besides a README:14 data files (ASCII), including headers explaining the dataBrief file description:Simulation results:- BICYCLE-SE_all_forcing_5ma_withheader.dat Important forcing time series for the BICYCLE-SE model- BICYCLE-SE_18scenariosatmCO25Ma_withheader.dat Simulated atmospheric CO2 concentration using the BICYCLE-SE model for 18 different scenarios- BICYCLE-SE_18scenariosod13C5Ma_withheader.dat Simulated mean ocean 𝛿13C using the BICYCLE-SE model for 18 different scenarios- BICYCLE-SE_4scenariosAtl_CO35Ma_withheader.dat Simulated CO3 in the Atlantic (surface and deep) using the BICYCLE-SE model for 4 different scenarios- BICYCLE-SE_4scenariosIPac_CO35Ma_withheader.dat Simulated CO3 in the Indo-Pacific (surface and deep) using the BICYCLE-SE model for 4 different scenarios- BICYCLE-SE_4scenariosAtl_IPac_CSH5Ma_withheader.dat Simulated Calcite Saturation Horizont (CSH) in the Atlantic and Indo-Pacific using the BICYCLE-SE model for 4 different scenarios- BICYCLE-SE_3scenarioscfluxes5Ma_withheader.dat Simulated C fluxes (volcanic CO2 ougassing, carbonate and silicate weathering, coral reef growth, ocean2sediment net flux, sediment accumulation) using the BICYCLE-SE model for 3 different scenarios- BICYCLE-SE_18scenariosseqAtl_seqIPacCO25Ma_withheader.dat Simulated pCO2 in surface equatorial Atlantic and in surface equatorial Indo-Pacific using the BICYCLE-SE model for 18 different scenarios- BICYCLE-SE_18scenariosseqAtl_seqIPacpH5Ma_withheader.dat Simulated pH in surface equatorial Atlantic and in surface equatorial Indo-Pacific using the BICYCLE-SE model for 18 different scenarios- BICYCLE-SE_18scenariosseqAtl_seqIPacDIC5Ma_withheader.dat Simulated dissolved inorganic carbon (DIC) in surface equatorial Atlantic and in surface equatorial Indo-Pacific using the BICYCLE-SE model for 18 different scenarios- BICYCLE-SE_18scenariosseqAtl_seqIPacTA5Ma_withheader.dat Simulated total alkalinity (TA) in surface equatorial Atlantic and in surface equatorial Indo-Pacific using the BICYCLE-SE model for 18 different scenariosAdditional supporting data:- lisiecki2014p_d13c_interNAtl_deepPac3Ma_withheader.dat 3 Ma of marine 𝛿13C based on Lisiecki (2014, doi:10.1002/2013PA002505).- poore2006ggg_d13c_global_NA_SO_PA5Ma_withheader.dat 5 Ma of marine 𝛿13C based on Poore et al. (2006, doi:10.1029/2005GC001085).- stap2018pp_CLIMBER_alternativeSST_5ma_withheader.dat 5 Ma of SST from CLIMBER model used as alternative forcing from Stap et al. (2018, doi:10.1002/2017PA003313).All further details are contained in the headers of the individual files.