The Middle Miocene Climate Transition was characterized by major Antarctic ice-sheet expansion and global cooling during the interval ~15-13 Ma. Here we present two sets of boundary conditions for global general circulation models characterizing the periods before (Middle Miocene Climatic Optimum; MMCO) and after (Middle Miocene Glaciation; MMG) the transition. These boundary conditions include Middle Miocene global topography, bathymetry and vegetation. Additionally, Antarctic ice volume and geometry, sea-level and atmospheric CO2 concentration estimates for the MMCO and the MMG are reviewed. The MMCO and MMG boundary conditions have been applied to the Community Climate System Model version 3 (CCSM3) to provide evidence of their suitability for global climate modeling. The boundary-condition files are available for use as input in a wide variety of global climate models and constitute a valuable tool for modeling studies with a focus on the Middle Miocene.

The mmco_topo_bathy_v1_0.nc and mmg_topo_bathy_v1_0.nc files contain global topography/bathymetry boundary conditions for global climate models for the MMCO and MMG periods, respectively.The mmco_veg_v1_0.nc and mmg_veg_v1_0.nc files contain global vegetation boundary conditions for global climate models for the MMCO and MMG periods, respectively.The MMCO_exp.nc, MMG_exp.nc, and PI_exp.nc files contain climatic model output data from three different experiments with CCSM3 using the above mentioned MMCO and MMG boundary conditions, and pre-industrial boundary conditions, respectively.

Supplement to: Frigola, Amanda; Prange, Matthias; Schulz, Michael (2018): Boundary conditions for the Middle Miocene Climate Transition (MMCT v1.0). Geoscientific Model Development, 11(4), 1607-1626