Browsing by Author "Chang, J"

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    Another piece of the Southern Hemispheric puzzle: developing a high-resolution climate record for multiple glacial cycles in eastern Australia
    (International Union For Quaternary Research (INQUA), 2015-08-01) Kermode, SJ; Shulmeister, J; Mueller, D; Goralewski, J; Gadd, PS; Chang, J; Heijnis, H; Cohen, TJ
    Understanding likely climate change and subsequent environmental responses is critical to our long term ability to manage and mitigate such changes. Investigations of previous responses to notable (either abrupt or large scale) climate change provides boundary conditions and targets that can be used to both validate and parameterize the climate models used to predict future change. High-resolution records from the Southern Hemisphere lag considerably behind available data from the Northern hemisphere, and are particularly sparse in Australia. Given that most (>80%) of Australia’s population, industry and agriculture lie in the mid-latitudes between Southern Queensland and Tasmania, one might expect that past climate changes from this region are well understood, but this is not the case. Long, high resolution records are needed to address this gap. An 11 m core has been collected from a permanent swamp/lagoon (Mountain Lagoon), in the Blue Mountains west of Sydney, which appears to span at least one complete glacial cycle. This is potentially the most continuous record recovered from this part of SE Australia. Much of the record is at least moderately organic and preliminary sedimentary and Itrax data indicate that significant environmental changes are recorded. Multi-proxy investigations including pollen, diatoms, charcoal and phytoliths are planned and the chronology will be underpinned using OSL and radiocarbon dating. The focus of the investigation will be to develop climatologies for the Sydney region during the last glacial cycle. The Mountain Lagoon project will consequently contribute to understanding how climate systems in SE Australia respond to large scale global change on Milankovitch time scales. By determining the climate response in Australia to these changes we will help predict future response in rainfall and temperature to human-induced and natural climate change.
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    Evidence against early nineteenth century major European induced environmental impacts by illegal settlers in the New England Tablelands, south eastern Australia.
    (Pergamon-Elsevier Science Ltd, 2011-12-01) Woodward, C; Chang, J; Zawadzki, A; Shulmeister, J; Haworth, R; Collecutt, S; Jacobsen, GE
    Paleoenvironmental reconstructions from Little Llangothlin Lagoon have been used to argue for early European impact on the eastern Australian landscape. In particular, these studies have argued for European arrival on the New England Tablelands at about 1800 AD, with significant impacts including the clearance of one species of Casuarina before 1820 AD and significant erosion by 1836 AD (Gale et al.. 1995: Gale and Pisanu, 2001; Gale and Haworth, 2002, 2005). We have re-cored the lagoon, dated the cores using (210)Pb and radiocarbon, and counted pollen and other proxies. Our (210)Pb results indicate that (210)Pb background was achieved stratigraphically later than the erosion event and we have three early Holocene radiocarbon ages in the erosion event interval. We conclude that the 'erosion event' predates European settlement. The (210)Pb results indicate much less erosion in response to European settlement than suggested by these earlier studies. We also find no notable decline in Casuarina in the pollen record spanning the time of initial European impact, and in fact we find very little Casuarina in the record. Instead of a Casuarina dominated vegetation we conclude that the area was dominated by open Eucalypt forest prior to European settlement. Rather than changes in the regional vegetation in the early 19th century, we attribute changes in the palynoflora spanning the 'erosion event' to changes within the lake/wetland and in particular to changes in the dominance of different species of Myriophyllum; most likely due to water depth fluctuation. This site has stood out as indicating an earlier European impact than other localities in eastern Australia, beyond the original limits of settlement near Sydney. Our findings suggest that a more traditional interpretation of this site is warranted and that no very early impact is discernable. (C) 2011 Elsevier Ltd. All rights reserved.
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    The fermi surface of Cu3Mn {100} and spinglass magnetism
    (Australian Institute of Physics, 2009-02-05) Stampfl, APJ; Loh, NA; Hsieh, KY; Yu, DH; Brigden, P; Stojanov, P; Riley, JD; Stamps, RL; Yuh, JY; Pi, TW; Chang, J; Hwu, YK
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