BAMOS February 2026
14 Article
From Australia to the world: ACCESS- ESM1.6 enters the global stage through CMIP7
Dr Tilo Ziehn, CSIRO( Tilo. Ziehn @ csiro. au)
Conceptual representation of the world. Credit: Canva
Australia’ s climate is influenced by processes that operate across the entire Earth system. This includes large-scale drivers such as the El Niño-Southern Oscillation( ENSO) and the Indian Ocean Dipole( IOD), as well as other complex interactions between physical and biogeochemical systems.
Australia’ s Earth System Model( ESM), Australian Community Climate and Earth‐System Simulator( ACCESS), integrates the atmosphere, oceans, land, sea ice, and the carbon cycle, enabling us to understand these interactions and explore past and future climate changes both in Australia and globally.
The model has been iteratively improved over decades. The latest version, ACCESS-ESM1.6, was developed collaboratively by CSIRO and Australia’ s climate simulator( ACCESS-NRI), with support from the NESP Climate Systems Hub, the Bureau of Meteorology and Australian universities. It is now being used in the Coupled Model Intercomparison Project Phase 7( CMIP7), which underpins the next Intergovernmental Panel on Climate Change( IPCC) report.
Participating in this international collaboration with ACCESS- ESM1.6 presents a crucial opportunity for Australia, ensuring its climate science is directly reflected in the evidence base shaping global climate policy.
In this article, we explore the new model version, its advancements, and its role in both CMIP7 and Australian climate research.
A range of upgrades
ACCESS-ESM1.6 provides significant scientific upgrades and new features over the previous version, including improvements to software infrastructure and model performance.
One key new feature of the land surface model Community Atmosphere Biosphere Land Exchange( CABLE) is the addition of two vegetation classes specific to Australia— mesic trees( mostly eucalypt) and xeric trees( mostly semi-arid acacia). This upgrade improves the realism of our regional land surface and provides a more robust Australia-relevant ESM, which is critical for understanding and managing the climate risks faced by our nation and for providing more reliable estimates of carbon uptake and release.
The ocean biogeochemistry component World Ocean Model of Biogeochemistry and Trophic Dynamics( WOMBAT) has also been updated and now includes prognostic chlorophyll, explicit iron tracers within the ecosystem, dynamic feedbacks of CaCO3 production and dissolution, with carbon chemistry and carbon fluxes optimised to recent datasets.
Contribution to CMIP7
Experiments run with ACCESS-ESM1.6 are crucial for exploring pathways to net-zero carbon emissions and future climate in line with the Paris Agreement targets, including understanding the implications when those targets are exceeded.