News release

From: Australia's Climate Simulator (ACCESS-NRI)

Climate change will shape everything about life in Australia – from the homes we live in and the food we grow to the risks of bushfires, floods, and heatwaves. But what will that future look like? We can’t know without climate models.

Climate models are the only tools that allow us to glimpse what’s ahead and prepare for it. They guide decisions on infrastructure, agriculture, health, and industry and underpin the strategies that protect communities, economies and our environment. For Australia, having our own model is a national security consideration and essential to support our research. No other country will invest in understanding the unique drivers of our climate and its impacts.

This week, Australia’s latest climate model, called ACCESS-ESM1.6, is ready to enter the global stage through the Coupled Model Intercomparison Project (CMIP7), which will inform the next Intergovernmental Panel on Climate Change (IPCC) report.

“Participating in this global program is vital for Australia as it ensures Australian science informs global climate policy, with our model benchmarked for reliable use worldwide. As a leader of climate modelling in the Southern Hemisphere, Australia brings a unique and crucial global perspective,” says CSIRO’s Senior Principal Research Scientist Rachel Law, who is also the coordinator of the CMIP7 project in Australia.

Developed by a collaboration between CSIRO, Australia’s national science agency, and Australia’s climate simulator (ACCESS-NRI) and running on the National Computational Infrastructure (NCI), ACCESS-ESM1.6 simulates the atmosphere, oceans, land, sea ice, and carbon cycle – including Australian vegetation.

With an additional decade of climate data since CMIP6, this Australian submission will incorporate refined projections alongside significant scientific and technical model upgrades. Incorporating scientific developments means Australian decision-makers have the most geographically relevant information possible with rainfall and drought patterns influencing the role of native trees like eucalypts and acacias in carbon storage.

Beyond projecting hazards, this model is a testbed for solutions. Building on studies with earlier ACCESS versions, CSIRO scientists can use ACCESS-ESM1.6 to explore interventions before they happen in the real world - from large-scale reforestation to ocean-based carbon dioxide removal proposals.

“ACCESS-ESM1.6 opens new research possibilities as we address important questions for Australia on how we mitigate and adapt to a changing climate. For example, by simulating climate and carbon and their interactions together, we can assess the role of vegetation in determining pathways to net-zero emissions,” says CSIRO’s Principal Researcher Tilo Ziehn, science lead and co-developer of the model.

The release of ESM1.6 is a major collaborative effort involving multiple teams across CSIRO and Australia’s climate simulator, ACCESS-NRI. Without this close partnership between researchers and software engineers working together to ensure that complex natural processes are accurately represented in code and implemented reliably and efficiently, the vital bridge between scientific discovery and global climate action simply wouldn't exist.

“Compared with the submission for CMIP6, this time we are making much better use of our collaboration infrastructure to help ensure our results are reproducible and trackable, making it easier for researchers to run the model themselves” says Martin Dix, Associate Director for Model Development at ACCESS-NRI.

Global requirements mean that all participating models must reach a stable, balanced state - a process called "spin-up”- before they can be used to make future projections. Once the model has reached this equilibrium, it can simulate how the climate system will respond to changes like increasing greenhouse gases. ACCESS-ESM1.6 is in the final stage of this spin-up so it is ready to enter the project and meet the strict deadlines of the “CMIP7 Assessment Fast Track”, maximising the possibilities of the research being included in the IPCC report.

This achievement reflects a major collaborative effort across national research infrastructures. Climate models require supercomputers to solve millions of complex equations. ACCESS-ESM1.6 runs on NCI’s Gadi machine and will generate eight million gigabytes of data which is equivalent to 350 years of high-definition television streaming.

Australia’s climate future depends on decisions made today. ACCESS-ESM1.6 ensures those decisions are based on the best possible science – science designed for Australia.

Acknowledgements

The CMIP7 submissions are led by CSIRO with support from the Australian Government’s National Environmental Science Program (NESP) Climate Systems Hub, along with ACCESS-NRI and NCI, both funded through the National Collaborative Research Infrastructure Strategy (NCRIS) under the Department of Education.