JOURNAL OF QUATERNARY SCIENCE (2007) 22(5) 421–422 Copyright ß 2007 John Wiley & Sons, Ltd. Published online in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/jqs.1139
Quaternary climatic, environmental and archaeological change in Australasia CHRIS S. M. TURNEY,1 JAMES SCOURSE,2* DON RODBELL3 and CHRIS CASELDINE 4 1 GeoQuEST Research Centre, School of Earth and Environmental Sciences, University of Wollongong, Wollongong, New South Wales Australia 2 School of Ocean Sciences, University of Wales, Bangor, Menai Bridge, Anglesey, UK 3 Geology Department, Union College, Schenectady, New York, USA 4 Department of Geography, School of Geography, Archaeology and Earth Resources, University of Exeter, Penryn, Cornwall, UK Turney, C. S. M., Scourse, J., Rodbell, D. and Caseldine, C. 2007. Quaternary climatic, environmental and archaeological change in Australasia. J. Quaternary Sci., Vol. 22 pp. 421–422. ISSN 0267-8179. Received 4 April 2007; Revised 13 May 2007; Accepted 13 May 2007
Australasia lies in a critical part of the earth–ocean–atmosphere system. Several major oceanographic and atmospheric controls influence the climate and environment of the region and are potentially globally important. For instance, the northern part is influenced by variations in the position of the Inter-Tropical Convergence Zone and the Indo-Pacific Warm Pool (IPWP; the region where mean temperatures are above 288C); the latter the major source of global latent heat release. The size of the IPWP is sensitive to changes in the El Nin˜o-Southern Oscillation (ENSO), and hence the strength of atmospheric circulation across the Pacific. Australia’s climate is dominated by the dry, sinking air of the subtropical high-pressure belt that migrates across the continent through the year. In contrast, the mid-latitudes are dominated by westerly airflow centred over 408S, influencing both southern Australia and New Zealand. Ocean circulation also plays a potentially important role in the transmission of ENSO signals to high southern latitudes via the Antarctic Circumpolar Wave while the East Australian Current (EAC) has a significant influence on coastal regions of eastern Australia, with approximately half of the EAC flowing eastward at the Tasman Front towards New Zealand. The extent to which past changes in the above influenced human populations in the region and contributed to global change is a major challenge to the Quaternary community. Between 28 July and 3 August 2007, several hundred Quaternary scientists will be descending on the coastal Queensland city of Cairns to attend the XVII INQUA Congress. This meeting is particularly timely. In a period of changing global climatic and environmental conditions, it is critical we get a better handle on the natural variability of the earth– ocean–atmosphere system so as to mitigate and adapt to future change. With this in mind we have selected a range of papers that encompass the Australasian region and provide key insights into past change and human activity. Pillans (2007) provides a fascinating long-term perspective of the Australian landscape that allows Quaternary change to be put into context. He argues that although reconstructions * Correspondence to: J. Scourse, School of Ocean Sciences, University of Wales, Bangor, Menai Bridge, Anglesey, LL59 5AB, UK. E-mail:
[email protected]
indicate parts of the Australian continent have been subaerially exposed for hundreds of millions of years, burial and exhumation in combination with tectonic stability and increasing aridity played roles in the preservation of ancient landforms and regolith. Four papers make important contributions to reconstructing Quaternary environmental change. Fitzsimmons et al. (2007) describe a multidisciplinary study of dune systems at Lake Frome in the Strzelecki Desert. The results indicate that transverse and linear systems are controlled not only by arid conditions but by local hydrology, and that discrete periods of formation took place through the late Quaternary. Focusing on the end of Marine Isotope Stage (MIS) 3, Kemp and Spooner (2007) report an investigation into a channel in the Lachlan Valley, southeastern Australia. Optically stimulated luminescence dating demonstrates that the river system was capable of generating bankfull discharges six to eight times greater than the present day by around 34 000 years ago, consistent with cool, pluvial conditions before the Last Glacial Maximum (LGM). In Victoria, Kershaw et al. (2007) report an exceptionally long high-resolution palynological record from Caledonia Fen. This 140 000 year sequence documents three phases of afforestation, during the Holocene, the Last Interglacial and an interstadial early in MIS 3. Importantly the record also documents millennial-scale variability in vegetation dynamics during the last glacial stage, suggesting the influence of North Atlantic events on the global system. Newnham et al. (2007) make a convincing case that the community should re-evaluate the definition of the LGM. A new pollen record from Kohuora maar crater, Auckland, New Zealand, displays vegetation and climatic changes over the past 32 000 years. This record and others from across the Southern Hemisphere show that glacial conditions prevailed during the interval 29 000 to 19 000 years ago, longer and earlier than the LGM as it is strictly defined. Two papers make important contributions to quantifying past climate change. Burge and Shulmeister (2007) provide a fossil beetle reconstruction for two windows of time within the last glacial period in the northwest coast of South Island, New Zealand. Mean summer temperatures appear to have been up to 38C cooler than present day, while mean minimum winter
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temperatures were probably 58C lower, suggesting increased seasonality. Overall, the data suggest a 30–40% decrease in mean annual precipitation compared to modern values. Closer in time, Wilmshurst et al. (2007) report a pre-deforestation pollen database that has been used to develop a pollen rain–vegetation climate relationship for quantifying New Zealand climate over the past 18 000 years. The results demonstrate significant climate variability; for instance, warming across the Younger Dryas chronozone culminated in a Holocene thermal optimum that may have been between 1.5 and 38C warmer than present day. Within the context of the above environmental and climatic changes, human colonisation and settlement took place in the region. Precise dating of occupation horizons within archaeological sequences requires a high level of stratigraphic integrity, however. Unfortunately, excavations of Australian sediments dating to the earliest period of occupation are relatively rare. Here, David et al. (2007) report a multidisciplinary study of the Nonda Rock archaeological site in north Queensland. Dating of the sediments indicate human occupation took place sometime between 67 000 and 40 000 years ago. Excitingly, at the same time as human colonisation of Australia, a different species of human was firmly established on the Indonesian island of Flores. Here, Westaway et al. (2007) report some fascinating stalagmite records that span the final known period of Homo floresiensis (‘the Hobbits’). d18O values from western Flores and eastern Java identify a series of isotopic shifts that reflect changes in the amount of rainfall and moisture sources. At present, however, it is unclear whether the abrupt disappearance of Homo floresiensis and associated megafauna was driven by a major change in climate, or the result of a volcanic eruption and/or modern human arrival. We hope the above provide a refreshing range of papers that encompass the aims of the INQUA meeting and form the basis for future discussion.
Copyright ß 2007 John Wiley & Sons, Ltd.
References Burge PI, Shulmeister J. 2007. An MIS 5a to MIS 4 (or early MIS 3) environmental and climatic reconstruction from the northwest South Island, New Zealand, using beetle fossils. Journal of Quaternary Science 22: 501–516. David B, Roberts RG, Magee J, Mialanes J, Turney C, Bird M, White C, Fifield LK, Tibby J. 2007. Sediment mixing at Nonda Rock: investigations of stratigraphic integrity at an early archaeological site in northern Australia and implications for the human colonisation of the continent. Journal of Quaternary Science 22: 449–479. Fitzsimmons KE, Bowler JM, Rhodes EJ, Magee JM. 2007. Relationships between desert dunes during the late Quaternary in the Lake Frome region, Strzelecki Desert, Australia. Journal of Quaternary Science 22: 549–558. Kemp J, Spooner NA. 2007. Evidence for regionally wet conditions before the LGM in southeast Australia: OSL ages from a large palaeochannel in the Lachlan Valley. Journal of Quaternary Science 22: 423–427. Kershaw AP, McKenzie GM, Porch N, Roberts RG, Brown J, Heijnis H, Orr ML, Jacobsen G, Newall PR. 2007. A high-resolution record of vegetation and climate through the last glacial cycle from Caledonia Fen, southeastern highlands of Australia. Journal of Quaternary Science 22: 481–500. Newnham RM, Lowe DJ, Giles T, Alloway BV. 2007. Vegetation and climate of Auckland, New Zealand, since ca. 32 000 cal. yr ago: support for an extended LGM. Journal of Quaternary Science 22: 517–534. Pillans B. 2007. Pre-Quaternary landscape inheritance in Australia. Journal of Quaternary Science 22: 439–447. Westaway KE, Zhao J-X, Roberts RG, Chivas AR, Morwood MJ, Sutikna T. 2007. Initial speleothem results from western Flores and eastern Java, Indonesia: were climate changes from 47 to 5 ka responsible for the extinction of Homo floresiensis? Journal of Quaternary Science 22: 429–438. Wilmshurst JM, McGlone MS, Leathwick JR, Newnham RM. 2007. A pre-deforestation pollen–climate calibration model for New Zealand and quantitative temperature reconstructions for the past 18 000 years BP. Journal of Quaternary Science 22: 535–547.
J. Quaternary Sci., Vol. 22(5) 421–422 (2007) DOI: 10.1002/jqs
