• Energy Research

The Australian Community Climate and Earth System Simulator (ACCESS) has contributed to the World Climate Research Programme’s Coupled Model Intercomparison Project Phase 6 (CMIP6) using two fully coupled model versions (ACCESS-CM2 and ACCESS-ESM1.5) and two ocean–sea-ice model versions (1° and 0.25° resolution versions of ACCESS-OM2). The fully coupled models differ primarily in the configuration and version of their atmosphere components (including the aerosol scheme), with smaller differences in their sea-ice and land model versions. Additionally, ACCESS-ESM1.5 includes biogeochemistry in the land and ocean components and can be run with an interactive carbon cycle. CMIP6 comprises core experiments and associated thematic Model Intercomparison Projects (MIPs). This paper provides an overview of the CMIP6 submission, including the methods used for the preparation of input forcing datasets and the post-processing of model output, along with a comprehensive list of experiments performed, detailing their initialisation, duration, ensemble number and computational cost. A small selection of model output is presented, focusing on idealised experiments and their variants at global scale. Differences in the climate simulation of the two coupled models are highlighted. ACCESS-CM2 produces a larger equilibrium climate sensitivity (4.7°C) than ACCESS-ESM1.5 (3.9°C), likely a result of updated atmospheric parameterisation in recent versions of the atmospheric component of ACCESS-CM2. The idealised experiments run with ACCESS-ESM1.5 show that land and ocean carbon fluxes respond to both changing atmospheric CO2 and to changing temperature. ACCESS data submitted to CMIP6 are available from the Earth System Grid Federation (https://doi.org/10.22033/ESGF/CMIP6.2281 and https://doi.org/10.22033/ESGF/CMIP6.2288). The information provided in this paper should facilitate easier use of these significant datasets by the broader climate community.

This record contains ACCESS-OM2-025 simulation output accompanying the paper: England, M., Zhi, L., Huguenin, M., Kiss, A., Sen Gupta, A., Holmes, R. and Rahmstorf, S. (2025) Drivers of the unprecedented North Atlantic marineheat wave during 2023, Nature, XXX DOI TO BE INSERTED XX Data is provided for the two simulations used in the article: ACCESS-OM2-025_ERA5; the ERA5 forced version of ACCESS-OM2-025. ACCESS-OM2-025_JRA55; the JRA55-do forced version of ACCESS-OM2-025. Netcdf files are organised per year, for each of the years 1980-2010 (the climatology period) and 2023 (the analysis period). For the JRA55 run, data is only provided for the May-August months, which were the focus of the analysis. Each file contains monthly averages of the following variables: temp; the Conversative Temperature over the top 300m salt; Practical Salinity over the top 300m lw_heat; the net longwave heat flux across the sea surface swflx; the net shortwave heat flux across the sea surface sens_heat; the net sensible heat flux across the sea surface evap_heat; the net latent heat flux across the sea surface net_sfc_heating; the net surface heat flux across the sea surface mld; the mixed layer depth determined according to the 0.125kgm-3 density criterion sw_pen; the shortwave heat flux across the base of the mixed layer Variables are only provided over the North Atlantic region (100W-10E, 0-60N). More information on the simulations, please see the England et al. (2025) article itself, as well as the following related references: Kiss et al. (2020) ACCESS-OM2 v1.0: A global ocean--sea ice model at three resolutions, Geosci. Model Dev. , Vol. 13, No. 2, p. 401-442, https://dx.doi.org/10.5194/gmd-13-401-2020 (ACCESS-OM2 documentation paper) Mackallah et al. (2022) ACCESS datasets for CMIP6: methodology and idealised experiments, JSHESS , Vol. 72, No. 2, p. 93-116 , https://doi.org/10.1071/ES21031 (contains information on the JRA55 run which was published up to 2018 as part of CMIP6, OMIP-2).