Hydroclimate variability in the eastern Kimberley, Australia, since the last deglaciation

Abstract

The climate of the Kimberley region in tropical northwest Australia is dominated by the Indo-Australian summer monsoon (IASM). Understanding of the palaeoclimate since the Last Glacial Maximum in this region, which is well placed to record IASM variations, is currently based on few records. Many of these are confounded by local environmental factors such as topography, anthropogenic activity or marine processes. Here, we present a geochemical record spanning the last 17 ka, in conjunction with pollen and charcoal records from 5.4 ± 0.1 ka (1 sigma uncertainty) to the present. The record comes from the floodplain of the Bullo River and as such represents variations in the hydroclimate of its 2000 km² catchment. Results show that the deglacial was characterised by a variable monsoon until the onset of a wet interval beginning at 12.9 ± 0.9 ka. The exact onset and intensity of a dry period following 5 ka are uncertain, but conditions became progressively drier until the climate amelioration to modern conditions. These results are broadly consistent with previous research and extend our understanding of deglacial and Holocene hydroclimate variability to the eastern Kimberley, 350 km east of previously published Kimberley palaeoenvironmental records.