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New high-resolution MC-ICPMS U/Th ages and C and O isotopic analyses from a Holocene speleothem in arid south-central Australia provide evidence for increased effective precipitation (EP) relative to present at c. 11.5 ka and c. 8—5 ka, peak moisture at 7—6 ka, and onset of an arid climate similar to present by c. 5 ka. δ18O and δ13C time-series data exhibit marked (>+1‰) contemporaneous excursions over base-line values of −5.3‰ and −11.0‰, respectively, suggesting pronounced moisture variability during the early middle Holocene ‘climatic optimum’. Optically stimulated luminescence and 14C ages from nearby terraced aggradational alluvial deposits indicate a paucity of large floods in the Late Pleistocene and at least five large flood events in the last c. 6 kyr, interpreted to mark an increased frequency of extreme rainfall events in the middle Holocene despite overall reduced EP. Increased EP in south-central Australia during the early to middle Holocene resulted from (1) decreased El Niño-Southern Oscillation (ENSO) variability, which reduced the frequency of El Niño-triggered droughts, (2) the prevalence of a more La Niña-like mean climatic state in the tropical Pacific Ocean, which increased available atmospheric moisture, and (3) a southward shift in the Intertropical Convergence Zone (ICTZ), which allowed tropical summer storms associated with the Australian summer monsoon (ASM) to penetrate deeper into the southern part of the continent. The onset of heightened aridity and apparent increase in large flood frequency at c. 5 ka is interpreted to indicate the establishment of an ENSO-like climate in arid Australia in the late Holocene, consistent with a variety of other terrestrial and marine proxies. The broad synchroneity of Holocene climate change across much of the Australian continent with changes in ENSO behavior suggests strong teleconnections amongst ENSO and the other climate systems such as the ASM, Indian Ocean Dipole, and Southern Annular Mode.

Pollen sequences from playa lakes in the Darling Anabranch dunefields of southwestern New South Wales record vegetation changes over the last glacial period and into the Holocene. This interval was one of marked taxonomic and structural reorganization, with the plant communities that became established after the last glacial maximum (LGM; ~24-18 ka) distinct from those that had prevailed over the build-up to full glacial conditions (~70-24 ka). The glacial period was characterized by a gradual reduction of woodland and tall shrubland cover. Recolonization of the dunefields involved a similar, gradual succession from herbfields and low shrublands to tall shrublands and, finally, woodlands. These changes are likely to have been driven by climatic change, particularly fluctuations in temperature, precipitation and atmospheric CO2, as global climate systems entered and emerged from the last glaciation.

Fossil bonanza A rich source of fossils recently discovered in caves beneath the arid, treeless Nullarbor Plain of western Australia offers a rare glimpse of life in the continent in the Middle Pleistocene (between around 800,000 and 200,000 years ago), long before humans arrived. Despite the remarkable diversity of animals and plants, including eight previously unknown kangaroo species, two of them tree kangaroos, the climate was similar to that of today. This means that climate change alone is unlikely to have been responsible for the subsequent wave of extinctions that swept away most of the Australian megafauna. How well the ecology, zoogeography and evolution of modern biotas is understood depends substantially on knowledge of the Pleistocene 1 , 2 . Australia has one of the most distinctive, but least understood, Pleistocene faunas. Records from the western half of the continent are especially rare 3 . Here we report on a diverse and exceptionally well preserved middle Pleistocene vertebrate assemblage from caves beneath the arid, treeless Nullarbor plain of south-central Australia. Many taxa are represented by whole skeletons, which together serve as a template for identifying fragmentary, hitherto indeterminate, remains collected previously from Pleistocene sites across southern Australia. A remarkable eight of the 23 Nullarbor kangaroos are new, including two tree-kangaroos. The diverse herbivore assemblage implies substantially greater floristic diversity than that of the modern shrub steppe, but all other faunal and stable-isotope data indicate that the climate was very similar to today. Because the 21 Nullarbor species that did not survive the Pleistocene were well adapted to dry conditions, climate change (specifically, increased aridity) is unlikely to have been significant in their extinction.

Aim Fossil pollen preserved within small salt lake basins in the Australian interior is used to reconstruct mid- to late Holocene vegetation. The study aims to identify the origin of problems such as woodland decline and salinization within present ecosystems. Location Warrananga and Tooperoopna salt lakes, south-western New South Wales, Australia. Methods Pollen, carbonized particle and sedimentological analyses of cores taken from salt lakes. Results Prior to c. 4500 years ago, the region supported a dense cover of Casuarinaceae woodlands. It is possible that the subhumid zone species Allocasuarina luehmannii comprised some of the Casuarinaceae element. In the late Holocene, A. luehmannii disappeared from the record and chenopodiaceous low shrublands expanded. About 2000 years ago, Callitris representation decreased. Woodland contraction also occurred after European settlement. Main conclusions Increasing aridity or greater seasonal variation in the climate during the late Holocene caused a contraction of woodland vegetation. Increased proportions of Chenopodiaceae may indicate soil salinization around the basins. A decrease in Callitris was possibly due to heightened severity or frequency of drought events after 2000 years ago. Decline in woodland pollen in the uppermost samples is explained by the preferential clearing of Callitris glaucophylla, Callitris gracilis and Casuarina pauper for timber and their limited regeneration because of browsing by stock and rabbits.

This paper presents some results of a ground penetrating radar survey conducted to establish the extent of the Willlandra Fossil Trackway, and further mapping of the footprints and intermingled tracks. In addition, it includes a refinement of the age range of the trackway, through further OSL dating, to between 19,000 and 20,000 years ago. Finally, it also provides a discussion of the geochemical composition of the trackway.

This paper presents some results of a ground penetrating radar survey conducted to establish the extent of the Willlandra Fossil Trackway, and further mapping of the footprints and intermingled tracks. In addition, it includes a refinement of the age range of the trackway, through further OSL dating, to between 19,000 and 20,000 years ago. Finally, it also provides a discussion of the geochemical composition of the trackway.