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The Yalgorup Plain of southwestern Australia is underlain by two limestone formations and a linear quartz-sand formation containing limestone lenses. These limestones record carbonate deposition in seagrass banks during the Pleistocene; they are capped either by a prograding beach-ridge system of small cuspate forelands or a quartz-rich shore-parallel coastal barrier. The cuspate forelands formed behind protective offshore limestone reefs within a given Pleistocene wind-and-wave field, while the quartz-rich coastal dune barrier formed under enhanced swell conditions. These formations record three different Pleistocene interglacial depositional events, separated by unconformities, each linked to a distinct climate and mean sea level. Foraminiferal assemblages within the two limestones and within the limestone lenses of the quartz-sand formation faithfully record changes in minimum seawater temperature, reflecting these changes in climate. They indicate a cycle of warm–cool–warm water accumulation of carbonates. Such a record of both climate and sea level history for southwestern Australia is unique, contributing greatly to the Pleistocene coastal sedimentary history of limestones within southwestern Australia. These formations occur within the globally unique setting of Western Australia and are conserved within a National Park and represent an outstanding record of Quaternary coastal geomorphic development in terms of both carbonate and siliciclastic sedimentation linked to both climate and sea level changes. Given their array of lithofacies, environmental setting, sea level and climate changes, as well as their biostratigraphy reflecting these changes, these formations form a sedimentary 'package' that is of global geoheritage significance, with many of its inherent geological features also of global to national geoheritage significance. [ABSTRACT FROM AUTHOR]

Anthropogenic climate change is the Earth's most serious large-scale environmental concern. While the projected changes of global temperatures, rainfall and surface water have been modelled in a sophisticated manner, the impact on groundwater resources is much less well constrained. In southeast Australia, the decrease in rainfall amount and an increase in temperature that are predicted by climate models are generally assumed to reduce the amount of recharge to the groundwater systems. However, the increase in recharge that has resulted from clearing of the native vegetation will almost certainly produce a greater impact on the groundwater system, increasing quantity and potentially improving quality. Additionally, the impact on recharge of changes to rainfall frequency rather than just total amount is not well documented. Overall our understanding of the impacts of climate change on groundwater systems is insufficiently advanced to make firm predictions. Indirect impacts of climate change, particularly the projected increased demand for groundwater or surface water to supplement surface water supplies also will have a major impact that may be greater than the direct effect of climate change. [ABSTRACT FROM AUTHOR]

Quantitative data bearing on Phanerozoic climates of Australia are summarised and comparisons are made with the predictions of atmospheric general circulation models over 12 time slices from the Silurian to the Miocene. Summaries of the model-derived mean temperature and precipitation conditions are given individually for each of four regions (southeast, northeast, southwest and northwest). Model results provide the means of estimating climate conditions in many cases, but there is fair agreement between the two approaches in most cases in which data are available. On model results, the southeast experienced winter freezing conditions from the Permian through until the middle Cretaceous and was consistently the coolest of the four regions, in part because of its proximity to the pole, but also because it was the site of elevated terrain throughout most of the Phanerozoic. It also tended to be among the wettest parts of Australia over this time and was subject to frequent winter storms. The northeast, in contrast, was often the warmest part of the continent, although strong seasonality and freezing winter temperatures were common during the Mesozoic and Palaeozoic. Strong seasonality (>30°C contrast between winter and summer) also apparently characterised most of the record for the southwest region, except for the Tertiary, part of the Jurassic, and the Early Palaeozoic. Together with the southeast, this region experienced the most intense effects of winter, especially in the Triassic. Strong seasonality also affected the northwest region through much of the Palaeozoic and Mesozoic and, interestingly, the highest summer temperatures on the continent are predicted for the southwest for most of the time slices studied. The models used today are imperfect but, nonetheless, offer a means of prediction and will perhaps stimulate the gathering of quantitative data in a continent where information is hard to come by and for which not much has yet been presented. [ABSTRACT FROM AUTHOR]