Complex climate models, such as ACCESS, play a central role in understanding the causes of past climate variability through simulation experiments of the Earth’s climate.
Understanding the causes of past climate variability and change gives us insights into the causes of possible future climate changes. Complex climate models, such as ACCESS, play a central role in this understanding through simulation experiments of the Earth’s climate.
Under the Coupled Model Intercomparison project version 6 (CMIP6), each Modelling Centre across the world (including Australia with ACCESS-CM2 and ACCESS-ESM1.5 simulations) must carry out a mandatory set of climate experiments using a common forcing dataset. They are also encouraged to perform additional sets of experiments targeted at understanding specific behaviours of the climate system. One of these additional sets is the ‘detection and attribution’ experiments (DAMIP), which use single climate variables, called forcing agents, to explore the role of these drivers in historical climate. These experiments are designed to facilitate a better understanding of the roles of human-induced and natural forcings on changes in temperature, rainfall and other climate variables by examining how well models represent historical changes in climate (‘detection’) and how well they can represent climate change using known climate forcings (‘attribution’).
In one study, ACCESS-CM2 and ACCESS-ESM1 .5 model simulations were used to investigate the effects of greenhouse gas, aerosol and natural forcings on past Global Mean Surface Temperature (GMST) changes.
These ACCESS model experiments, individually or combined with similar experiments from other climate models, facilitate the estimation of the climate changes attributable to human and natural causes. This information enables decision-makers to formulate sensible policies regarding future emissions of human-induced greenhouse gas emissions and aerosols for societal benefit.