Uncertainty in CMIP6 climate change projections for the Australian
monsoon is tied to hemispheric-scale changes
Abstract
Climate change projections for the Australian monsoon have been highly
uncertain in previous generations of coupled climate models. The new
Coupled Model Intercomparison Project Phase 6 (CMIP6) ensemble provides
an opportunity to address the uncertainty in future projections for
northern Australia. We find that the range in Australian monsoon
projections from the available CMIP6 ensemble is substantially reduced
compared to CMIP5, although models continue to disagree on the magnitude
and direction of change. While previous CMIP5 studies identified warming
in the western equatorial Pacific as important for Australian monsoon
projections, here we show that the western Pacific is not strongly
connected to northern Australian precipitation changes in the CMIP6
models. By comparing groups of models based on their future projections,
we note that the model-to-model differences in Australian monsoon
projections are congruent with the zonally averaged precipitation
response in the Southern Hemisphere tropics within each model.