05 Apr 2023
 | 05 Apr 2023
Status: a revised version of this preprint is currently under review for the journal CP.

Last Glacial Maximum Climate and Atmospheric Circulation over the Australian Region from Climate Models

Yanxuan Du, Josephine R. Brown, and J. M. Kale Sniderman

Abstract. The Last Glacial Maximum (LGM, ~21,000 years ago) was the most recent time that the Earth experienced global maximum ice volume and minimum eustatic sea level. The regional climate changes over Australia at the LGM remain uncertain. Four Coupled Model Intercomparison Project Phase 6 (CMIP6) models and eight Coupled Model Intercomparison Project Phase 5 (CMIP5) models that were included in the Paleoclimate Modelling Intercomparison Project (PMIP) Phases 3 and 4 were used in this research to investigate the temperature, precipitation, and wind changes over Australia at the LGM relative to pre-industrial (PI) and compare the results with existing proxy records and other model studies. The annual multi-model mean (MMM) Australian land surface temperature is estimated to cool by 2.6 °C at the LGM. All models show consistent cooling over the Australian region (0–45° S, 110° E–160° E). The MMM annual precipitation decreased by 0.16 mm/day at the LGM relative to PI over modern Australian mainland areas (10° S–45° S, 110° E–160° E). Precipitation minus evaporation patterns over Australia are also examined to assess the changes in moisture balance at the LGM. Despite reduced LGM precipitation, the greater decrease in LGM evaporation leads to a slightly positive moisture balance in many regions. This is in disagreement with some proxy-based hydroclimate reconstructions of reduced LGM moisture over Australia, which might be due to the interpretations of vegetation-based proxy records or the uncertainties in model representation of moisture fluxes. We find a small equatorward multi-model average displacement of the boundary line between Southern Hemisphere (SH) westerly and easterly winds at the LGM but large model disagreement on a shift in SH mid-latitude westerly winds at the LGM, similar to previous studies.

Yanxuan Du et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2023-19', Anonymous Referee #1, 15 May 2023
    • AC1: 'Reply on RC1', Yanxuan Du, 30 Jun 2023
  • RC2: 'Comment on cp-2023-19', Anonymous Referee #2, 18 May 2023
    • AC2: 'Reply on RC2', Yanxuan Du, 30 Jun 2023
  • RC3: 'Comment on cp-2023-19', Anonymous Referee #3, 18 May 2023
    • AC3: 'Reply on RC3', Yanxuan Du, 30 Jun 2023

Yanxuan Du et al.

Yanxuan Du et al.


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Short summary
This study provides an analysis of the response of climate (temperature, precipitation, wind and atmospheric circulation) over the Australian region in climate model simulations of the Last Glacial Maximum (21,000 years before present). Model results are evaluated and compared with available paleoclimate proxy records. Analysis of the moisture balance (precipitation minus evaporation) demonstrates that the Australian climate may not have been uniformly drier during the glacial period.