ACCESS Impact as a Global Climate Model

ACCESS models and expertise of researchers has helped significantly to understand Australia’s future climate, as part of the International Coupled Model Intercomparison Project (CMIP6)

The last Coupled Model Intercomparison project (CMIP6) multi-model ensemble provides researchers around the world with a new opportunity to examine the climate system. CMIP6 is of strong interest for both assessing climate change processes and for producing updated national climate change projections for Australia.

Researchers from the Climate Hub at CSIRO found that the projections of Australian mean and extreme climates are broadly similar in CMIP5 (the previous CMIP project which ended in 2013) and CMIP6 in terms of directions of change and spatial distributions. Both CMIP ensembles project warming temperatures and increases in hot extremes, which depend on the greenhouse gas emission trajectory input into the models (i.e. low, mid or high emissions scenario). However, warmest projections beyond 2050 from CMIP6 are higher than those from CMIP5 and include a possible change of over 6 °C mean annual temperature from the preindustrial baseline by 2100 under a high-emissions scenario.

CMIP5 and CMIP6 projections both indicated significant future drying of southwest Australia in the cool season and less significant rainfall changes in other regions. The CMIP6 ensemble so far suggests there is greater confidence (as indicated by greater model agreement) in rainfall decrease in Southern Australia in the cool season than in CMIP5. There is also a smaller inter-model range of rainfall change in Northern Australia during the austral warm season and in Southern Australia during the cold season in CMIP6 compared to CMIP5. If this result is maintained as more models are added to CMIP6 evaluation efforts, these projections will be a strong line of evidence to support the need for more targeted and specific adaptation actions to adequately manage Australia’s water resources into the future.