Session: Warm Climates (Mid-Holocene, Last interglacial, Deep-time, Pliocene)
Author: Otto-Bliesner, Bette L / ottobli@ucar.edu / National Center for Atmospheric Research
Co-author: Brady, Esther C, National Center for Atmospheric Research;
                    Tomas, Robert, National Center for Atmospheric Research;

Abstract:
Two interglacial epochs are included in the suite of Paleoclimate Modeling Intercomparison Project (PMIP4) simulations in the Coupled Model Intercomparison Project (CMIP6). Experimental protocols have been established for the Tier 1 simulations of the mid-Holocene [midHolocene, 6000 years before present] and the Last Interglacial [lig127k, 127,000 years before present] (Otto-Bliesner et al., Geoscientific Model Development Discussions, 2016). These equilibrium simulations are designed to examine the impact of changes in orbital forcing at times when atmospheric greenhouse gas levels were similar to those of the preindustrial period and the continental configurations were almost identical to modern. The changes in insolation are characterized by enhanced seasonal contrast in the northern hemisphere (NH) (and reduced seasonal contrast in the southern hemisphere, SH), with these changes stronger in the lig127k experiment than the midHolocene experiment. Here, we report on the lig127k and midHolocene simulations with the Community Earth System Model, version 2 (CESM2), the same model and same resolution as is being used for the CMIP6 DECK, historical, and future projection simulations. The results will be compared to the CMIP5/PMIP3 simulations with the Community Climate System Model, version 4 (CCSM4). Otto-Bliesner, B.L. et al., 2016: The PMIP4 contribution to CMIP6 - Part 2: Two Interglacials, Scientific Objective and Experimental Design for Holocene and Last Interglacial Simulations. Geosci. Model Dev. Discuss., doi:10.5194/gmd-2016-279.