MioMIP2: Experimental design for Phase 1 & 2 of the Miocene component of the CMIP7/PMIP7 Deep-time Model Intercomparison Project (DeepMIP-Miocene)

Abstract. The Miocene Epoch has emerged as an important paleoclimate model intercomparison target due to its dynamic nature, global warmth, and reconstructed atmospheric CO₂ concentrations. Miocene CO₂ estimates range from as low as 300–600 ppmv to as high as 800–1100 ppmv. The formalized Miocene Model Intercomparison Project (MioMIP2) aims to address questions about the mechanisms driving the climatic changes and tipping points seen in the geological record and improve confidence in the ability of climate models to predict future climates and constrain climate sensitivity. Through alignment with PlioMIP and DeepMIP-Eocene efforts, a coordinated MioMIP (DeepMIP-Miocene) effort will allow for cross-time-period studies that sample the full range of Shared Socioeconomic Pathway paleo analogues. Building on the MioMIP1 “MIP of opportunity”, the Miocene community has been developing the experimental design for MioMIP2. The MioMIP1 effort was an ensemble of opportunity that leveraged existing Miocene simulations run with different models, boundary conditions, and reference datasets. MioMIP2 will be the first formal Miocene MIP with common boundary conditions and will target the Miocene Climatic Optimum (MCO; 16.75–14.5 Ma). We present the experimental design for coordinated “CORE” MCO simulations and sensitivity studies. This community effort synthesizes paleogeography, ice sheet, CO₂, and vegetation boundary conditions based on the latest available literature and will use geological data from companion proxy synthesis efforts to evaluate the simulations.