Last Glacial Maximum climate and atmospheric circulation over the Australian region from climate models

Last Glacial Maximum climate and atmospheric circulation over the Australian region from climate models

The Last Glacial Maximum (LGM; ∼21 kyr ago) was the most recent time that the Earth experienced global maximum ice volume and minimum eustatic sea level. The climate changes over the Australian region at the LGM remain uncertain, including the extent of cooling in the arid interior, changes in the r...

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Bibliographic Details
Published in:Climate of the past Vol. 20; no. 2; pp. 393 - 413
Main Authors: Du, Yanxuan, Brown, Josephine R, Sniderman, J. M. Kale
Format: Journal Article
Language:English
Published: Katlenburg-Lindau Copernicus GmbH 26-02-2024
Copernicus Publications
Subjects:
Air temperature
Analysis
Atmospheric circulation
Atmospheric circulation changes
Atmospheric models
Boundary conditions
Circulation
Climate change
Climate models
Cooling
Eustatic changes
Evaporation
Glacial climates
Ice volume
Intercomparison
Last Glacial Maximum
Latitude
Modelling
Moisture
Paleoclimate
Precipitation
Precipitation (Meteorology)
Precipitation anomalies
Regional climates
Regions
Sea level
Sea level changes
Simulation
Surface temperature
Surface-air temperature relationships
Temperature
Tropical circulation
Vegetation
Westerlies
Wind
Australia
New Guinea
Southeast Asia
Eurasia
Tasmania Australia
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Summary:The Last Glacial Maximum (LGM; ∼21 kyr ago) was the most recent time that the Earth experienced global maximum ice volume and minimum eustatic sea level. The climate changes over the Australian region at the LGM remain uncertain, including the extent of cooling in the arid interior, changes in the regional atmospheric circulations such as the tropical monsoon and mid-latitude westerlies, and changes in the balance between precipitation and evaporation. In this study, 13 climate model simulations that were included in the Paleoclimate Modelling Intercomparison Project (PMIP) Phases 3 and 4 are used to investigate regional climate (temperature, precipitation, and wind) over Australia at the LGM. The model simulations are compared with existing proxy records and other modelling studies. All models simulate consistent annual and seasonal cooling over the Australian region (defined as 0–45° S, 110–160° E) at the LGM compared to pre-industrial, with a multi-model mean 2.9 °C decrease in annual average surface air temperature over land at the LGM compared to pre-industrial. Models simulate a range of LGM precipitation anomalies over the region. Simulated precipitation changes over tropical Australasia appear to be driven by changes in circulation and moisture transport, which vary greatly between models. Surface moisture balance calculated from precipitation minus evaporation shows little change over much of the Australian land area at the LGM. Changes in the strength and position of the mid-latitude westerlies are uncertain, with wide model disagreement. These results indicate that climate model simulations do not show a robust response in either tropical or mid-latitude circulation to LGM boundary conditions, suggesting that caution is required when interpreting model output in this region. Further analysis based on model evaluation and quantitative model–proxy comparison is required to better understand the drivers of LGM climate and atmospheric circulation changes in this region.
ISSN:1814-9332
1814-9324
1814-9332
DOI:10.5194/cp-20-393-2024