ACCESS-CM2, a new generation of the ACCESS coupled model, has been developed at the Climate Science Centre, CSIRO Oceans and Atmosphere for the purpose of global climate and climate change research and applications. We have two versions of ACCESS-CM2 ready for Australia’s contribution to the Coupled Model Inter-comparison Project Phase 6 (CMIP6). The first version (ACCESS-CM2.0) contains the UK Met Office atmospheric model (UM10.6/GA7.1, with the JULES land surface model), the GFDL ocean model (MOM5), the Los Alamos sea ice model (CICE5.1), and a European numerical coupler (OASIS3-MCT). The second version (ACCESS-CM2.1) is identical to ACCESS-CM2.0 except the land surface model has been replaced with the CSIRO land surface model CABLE2. Both versions are configured with horizontal resolution of N96 UM atmosphere (and land surface model Jules/CABLE) and 1-degree ocean-sea ice.
Multi-century spin-up simulations with pre-industrial forcing have been performed using ACCESS-CM2.0 and 2.1, respectively, and the official CMIP6 experiments have then followed. Preliminary results from the piControl (500 years), historical (1850-2014), 1%/year compounding CO2 growth (150 years) and an abrupt 4xCO2 change (150 years) runs provided by the two model versions are presented and compared, for the purpose of assessing the overall performance of ACCESS-CM2 in simulating the global pre-industrial climate, climate variability, and climate change due to greenhouse gas increase in the atmosphere.