Browsing by Author "Brooke, BP"

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    Building 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, N
    In 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.
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    Contrasting sedimentation rates in Lake Illawarra and St Georges Basin, two large barrier estuaries on the southeast coast of Australia
    (Springer, 2011-12-01) Sloss, CR; Jones, BG; Brooke, BP; Heijnis, H; Murray-Wallace, CV
    Sedimentation rates over the last 100 years within two lagoons on the southeast coast of Australia, Lake Illawarra and St Georges Basin, have been quantified to determine the effects of catchment land use change and native vegetation clearance on infill rates, and spatial variations in the rate at which the estuaries have filled. Both catchments have similar lake and catchment area but have experience different degrees of modification due to land clearing for agriculture practices, urbanisation and industrialisation. Results indicate that in the heavily modified catchment of Lake Illawarra sedimentation rates close to fluvial deltas can be in excess of 16 mm/year, and between 2 and 4 mm/year in the adjacent central basin. This is approximately an order of magnitude greater than the pre-European rates. In contrast, at St Georges Basin, where the catchment has experienced much less modification, sedimentation rates in the central basin appear to have remained close to those prior to European settlement. However, sedimentation rates in the urbanized margin of St Georges Basin are relatively high (up to 4.4 mm/year). This rapid modern sedimentation in the margin of the estuarine embayments has been detected in several other estuaries in the region. However the degree of sedimentation within the bay-head deltas, and more significantly in the central basin appears proportional to the degree clearance of native vegetation (forest) in the catchment, urban expansion and development of heavy industry in the respective catchment areas. © 2011, Springer.
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    Morphology and formation of relict coral reef on the shelf around Lord Howe Island.
    (GeoHab (Marine Geological and Biological Habitat Mapping), 2010-05-06) Woodroffe, CD; Brooke, BP; Linklater, M; Kennedy, DM; Jones, BG; Buchanan, C; Mleczko, R; Hua, Q; Zhao, JX
    Coral reefs track sea level and are particularly sensitive to changes in climate. Reefs are threatened by global warming, with those in tropical waters experiencing increased incidences of bleaching. Although it has been suggested that reefs may extend poleward at their latitudinal limit, there has been little evidence to support this contention. In this paper, we report on a much more extensive coral reef that flourished around Lord Howe Island, which presently supports the southernmost coral reef in the Pacific. Multibeam swath mapping and sub-bottom profiling reveal an extensive reef that encircled the island, in the middle of the shelf, rising from water depths of around 50 m to 30 m, with isolated peaks reaching 23.5 m. Coring has indicated that this relict reef is composed of corals that grew between 9200 and 7100 years ago, and that the main phase of reef growth had terminated and the reef backstepped by 7000 years BP. Localised re-establishment of corals over the surface around 2500 and in the past few hundred years provides some indication that corals may be able to recolonise the relict reef and extend further in response to warmer temperatures anticipated later this century and beyond. However, this will depend on the availability of suitable substrate, as well as other environmental factors, as the relict reef is now in greater water depths than when it was most actively growing.