Browsing by Author "Kershaw, P"
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- ItemBuilding a future on knowledge from the past: what paleo-science can reveal about climate change and its potential impacts in Australia(Commonwealth Scientific and Industrial Research Organisation, 2005-06) Harle, KJ; Etheridge, DM; Whetton, P; Jones, R; Hennessy, K; Goodwin, ID; Brooke, BP; van Ommen, TD; Barbetti, M; Barrows, TT; Chappell, J; De Deckker, P; Fink, D; Gagan, MK; Haberle, SG; Heijnis, H; Henderson-Sellers, A; Hesse, PP; Hope, GS; Kershaw, P; Nicholls, NIn Australia, high quality instrumental climate records only extend back to the late 19th century and therefore only provide us with a brief snapshot of our climate, its mean state and its short-term variability. Palaeo-records extend our knowledge of climate back beyond the instrumental record, providing us with the means of testing and improving our understanding of the nature and impacts of climate change and variability in Australia. There is a vast body of palaeo-records available for the Australian region (including Antarctica), ranging from continuous records of sub-decadal up to millennial scale (such as those derived from tree rings, speleothems, corals, ice cores, and lake and marine sediments) through to discontinuous records representing key periods in time (such as coastal deposits, palaeo-channels, glacial deposits and dunes). These records provide a large array of evidence of past atmospheric, terrestrial and marine environments and their varying interactions through time. There are a number of key ways in which this evidence can, in turn, be used to constrain uncertainties about climate change and its potential impacts in Australia.
- ItemLate quaternary fire regimes of Australasia(Elsevier, 2011-01) Mooney, SD; Harrison, SP; Bartlein, PJ; Daniau, AL; Stevenson, J; Brownlie, KC; Buckman, S; Cupper, ML; Luly, J; Black, M; Colhoun, EA; D’Costa, D; Dodson, JR; Haberle, SG; Hope, GS; Kershaw, P; Kenyon, C; McKenzie, M; Williams, NWe have compiled 223 sedimentary charcoal records from Australasia in order to examine the temporal and spatial variability of fire regimes during the Late Quaternary. While some of these records cover more than a full glacial cycle, here we focus on the last 70,000 years when the number of individual records in the compilation allows more robust conclusions. On orbital time scales, fire in Australasia predominantly reflects climate, with colder periods characterized by less and warmer intervals by more biomass burning. The composite record for the region also shows considerable millennial-scale variability during the last glacial interval (73.5–14.7 ka). Within the limits of the dating uncertainties of individual records, the variability shown by the composite charcoal record is more similar to the form, number and timing of Dansgaard–Oeschger cycles as observed in Greenland ice cores than to the variability expressed in the Antarctic ice-core record. The composite charcoal record suggests increased biomass burning in the Australasian region during Greenland Interstadials and reduced burning during Greenland Stadials. Millennial-scale variability is characteristic of the composite record of the sub-tropical high pressure belt during the past 21 ka, but the tropics show a somewhat simpler pattern of variability with major peaks in biomass burning around 15 ka and 8 ka. There is no distinct change in fire regime corresponding to the arrival of humans in Australia at 50 ± 10 ka and no correlation between archaeological evidence of increased human activity during the past 40 ka and the history of biomass burning. However, changes in biomass burning in the last 200 years may have been exacerbated or influenced by humans. © 2011, Elsevier Ltd.
- ItemPaleoclimate studies and natural-resource management in the Murray-Darling Basin I: past, present and future climates(Taylor & Francis, 2013-06-19) Mills, K; Gell, PA; Hesse, PP; Jones, R; Kershaw, P; Drysdale, RN; McDonald, JThis paper provides an incisive review of paleoclimate science and its relevance to natural-resource management within the Murray-Darling Basin (MDB). The drought of 1997–2010 focussed scientific, public and media attention on intrinsic climate variability and the confounding effect of human activity, especially in terms of water-resource management. Many policy and research reviews make statements about future planning with little consideration of climate change and without useful actionable knowledge. In order to understand future climate changes, modellers need, and demand, better paleoclimate data to constrain their model projections. Here, we present an insight into a number of existing long-term paleoclimate studies relevant to the MDB. Past records of climate, in response to orbital forcing (glacial–interglacial cycles) are found within, and immediately outside, the MDB. High-resolution temperature records, spanning the last 105 years, exist from floodplains and cave speleothems, as well as evidence from lakes and their associated lunettes. More recently, historical climate records show major changes in relation to El Niño–Southern Oscillation cycles and decadal shifts in rainfall regimes. A considerable body of research currently exists on the past climates of southeastern Australia but, this has not been collated and validated over large spatial scales. It is clear that a number of knowledge gaps still exist, and there is a pressing need for the establishment of new paleoclimatic research within the MDB catchment and within adjacent, sensitive catchments if past climate science is to fulfil its potential to provide policy-relevant information to natural-resource management into the future. © 2013, Taylor & Francis.
- ItemPaleoclimate studies and natural-resource management in the Murray-Darling Basin II: unravelling human impacts and climate variability(Taylor and Francis Group, 2013-08-09) Mills, K; Gell, PA; Gergis, J; Baker, PJ; Finlayson, CM; Hesse, PP; Jones, R; Kershaw, P; Pearson, S; Treble, PC; Barr, C; Brookhouse, MT; Drysdale, RN; McDonald, J; Haberle, SG; Reid, M; Thoms, M; Tibby, JThe management of the water resources of the Murray-Darling Basin (MDB) has long been contested, and the effects of the recent Millennium drought and subsequent flooding events have generated acute contests over the appropriate allocation of water supplies to agricultural, domestic and environmental uses. This water-availability crisis has driven demand for improved knowledge of climate change trends, cycles of variability, the range of historical climates experienced by natural systems and the ecological health of the system relative to a past benchmark. A considerable volume of research on the past climates of southeastern Australia has been produced over recent decades, but much of this work has focused on longer geological time-scales, and is of low temporal resolution. Less evidence has been generated of recent climate change at the level of resolution that accesses the cycles of change relevant to management. Intra-decadal and near-annual resolution (high-resolution) records do exist and provide evidence of climate change and variability, and of human impact on systems, relevant to natural-resource management. There exist now many research groups using a range of proxy indicators of climate that will rapidly escalate our knowledge of management-relevant, climate change and variability. This review assembles available climate and catchment change research within, and in the vicinity of, the MDB and portrays the research activities that are responding to the knowledge need. It also discusses how paleoclimate scientists may better integrate their pursuits into the resource-management realm to enhance the utility of the science, the effectiveness of the management measures and the outcomes for the end users. © 2020 Informa UK Limited
- ItemStratigraphy and sedimentology of the longest terrestrial record in NE-Australia: Lynch’s Crater(Elsevier, 2007-07) Wust, R; Kershaw, P; Rieser, U; Jacobsen, GE; Deino, ALynch’s Crater on the Atherton Tablelands in NE-Australia, formed some >200,000 years ago during an explosive eruption of basaltic material creating a maar more than 80 m deep. The crater walls are highly weathered and are blanketed by thick (>2 m) sequences of laterites that contain slates and other metasedimentary rocks (up to boulder size) and various types of volcanic rock fragments. Since the eruption, the maar has been filled with lake sediments that are topped by peat material and the recovered core was 64 m long. The basal sediments below 62.75 m are composed of massive grey silty-sandy clays with abundant rock fragments including basalts, vein quartz and other quartz-rich metasediments. The subsequent 50 m thick lake sediments are composed of massive and laminated sediments. The bottom lake sediments have frequent thick (up to > 2 cm) turbidite sequences while the top sediments have only few thin (max few mm) clay-rich turbidite deposits. Beside the turbidite layers, the lake sediments are either massive or laminated. Most of the sediments in particular in the upper 30 m are laminated. The varves are chemical varves with various colours from dark green, dark blue (vivianite) to black. The top 13–16 m (depending on the location in the crater) are composed of mainly minerotrophic peats and represent the past 60 ka. Geochemical analysis shows that Heinrich and Dangaard-Oeschger events can be detected. Here we present in detail stratigraphic and geochemical changes and present evidence for environmental changes of the entire core. The geochronology is based on C14 AMS, OSL and Ar-Ar dates.