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Major aridification events in Australia during the Pliocene may have had significant impact on the distribution and structure of widespread species. To explore the potential impact of Pliocene and Pleistocene climate oscillations, we estimated the timing of population fragmentation and past connectivity of the currently isolated but morphologically similar subspecies of the widespread brushtail possum (Trichosurus vulpecula). We use ecological niche modeling (ENM) with the current fragmented distribution of brushtail possums to estimate the environmental envelope of this marsupial. We projected the ENM on models of past climatic conditions in Australia to infer the potential distribution of brushtail possums over 6 million years. D‐loop haplotypes were used to describe population structure. From shotgun sequencing, we assembled whole mitochondrial DNA genomes and estimated the timing of intraspecific divergence. Our projections of ENMs suggest current possum populations were unlikely to have been in contact during the Pleistocene. Although lowered sea level during glacial periods enabled connection with habitat in Tasmania, climate fluctuation during this time would not have facilitated gene flow over much of Australia. The most recent common ancestor of sampled intraspecific diversity dates to the early Pliocene when continental aridification caused significant changes to Australian ecology and Trichosurus vulpecula distribution was likely fragmented. Phylogenetic analysis revealed that the subspecies T. v. hypoleucus (koomal; southwest), T. v. arnhemensis (langkurr; north), and T. v. vulpecula (bilda; southeast) correspond to distinct mitochondrial lineages. Despite little phenotypic differentiation, Trichosurus vulpecula populations probably experienced little gene flow with one another since the Pliocene, supporting the recognition of several subspecies and explaining their adaptations to the regional plant assemblages on which they feed. [ABSTRACT FROM AUTHOR]

Understanding the key dynamical and microphysical mechanisms driving precipitation in the Snowy Mountains region of southeast Australia, including the role of orography, can help improve precipitation forecasts, which is of great value for efficient water management. An intensive observation campaign was carried out during the 2018 austral winter, providing a comprehensive range of ground-based observations across the Snowy Mountains. We used data from three vertically pointing rain radars, cloud radar, a PARSIVEL disdrometer, and a network of 76 pluviometers. The observations reveal that all of the precipitation events were associated with cold front passages. About half accumulated during the frontal passage associated with deep, fully glaciated cloud tops, while the rest occurred in the postfrontal environment and were associated with clouds with supercooled liquid water (SLW) tops. About three-quarters of the accumulated precipitation was observed under blocked conditions, likely associated with blocked stratiform orographic enhancement. Specifically, more than a third of the precipitation resulted from moist cloudless air being lifted over stagnant air, upwind from the barrier, creating SLW-top clouds. These SLW clouds then produced stratiform precipitation mostly over the upwind slopes and mountain tops, with hydrometeors reaching the mountain tops mostly as rimed snow. Two precipitation events were studied in detail, which showed that during unblocked conditions, orographic convection invigoration and unblocked stratiform enhancement were the two main mechanisms driving the precipitation, with the latter being more prevalent after the frontal passage. During these events, ice particle growth was likely dominated by vapor deposition and aggregation during the frontal periods, while riming dominated during the postfrontal periods. [ABSTRACT FROM AUTHOR]

Depositional evidence for glaciation (dropstones, diamictites) is common in Neoproterozoic strata, and often debated, but erosional evidence (e.g., unconformities cut directly by ice) is rare. Only two such unconformities are known to have been well preserved globally from the Ediacaran Period (in western Australia and central China). This paper provides the first full description of a spectacular subglacial landscape carved beneath ice masses in the Shimengou area of central China, with classical subglacial bed forms including general faceted forms, müschelbruche, cavetto, spindle forms, and striations that testify to an abundance of meltwater during subglacial erosion. These features were produced during the southward, somewhat sinuous, flow of a temperate to polythermal ice mass. [ABSTRACT FROM AUTHOR]

Australia is a continent seemingly without a cryohistory. But take a closer look. Its cryohistory differs dramatically from that of the northern hemisphere-a contrast that long baffled Victorian geologists seeking evidence of glaciation in the Great South Land. Just as historians have sought to redress the image of a static Arctic through a new attention to its cryohistory, so too historians of Australia have sought to recover a continent that is anything but a "timeless land." Its long geological history-its cryohistory-framed Aboriginal lifeways across the continent, which in turn, shaped colonial encounters in the aftermath of British invasion in 1788. Guiding this historical project have been the moral challenges of the settler nation's legacy of Indigenous dispossession and displacement, and the unfolding planetary crisis of the Anthropocene and its implications for critically understanding deep time. This article examines the colonial hydrology of water scarcity in the goldfields of arid Western Australia in the late nineteenth century. It shows how access to freshwater became a flashpoint for relations between Indigenous and non-Indigenous peoples on an extractive frontier. At the turn of the twentieth century, water was the means by which to improve health, hygiene and cleanliness, without which the privileges of white civilisation could not be afforded. Although such conditions also developed elsewhere in settler Australia, the limited water availability on the eastern goldfields made the circumstances that emerged there especially dire. Accordingly, the material conditions of the arid inland- the product of Australia's Pleistocene-came to bear on the nature of the encounters between Indigenous and non-Indigenous peoples from the mid-nineteenth century. The very absence of ice in Australia's cryohistory left its mark on the peoples of the eastern goldfields. [ABSTRACT FROM AUTHOR]

Ocean basins are the ultimate repositories of sediment. Their slow, continuous accumulation over geologic history provides valuable archives that document major climate events and transitions in Earth history. Mineral dust plumes borne by prevailing winds are dominant sources of terrigenous sedimentation off regions such as the Saharan, Arabian, Kalahari, Patagonian, and Australian deserts. Scientific ocean drilling off Africa and Arabia has recorded consistent glacial-stage increases in eolian dust fluxes throughout the Pliocene-Pleistocene, where elevated dust flux values during glacial periods and stadia have been interpreted as reflecting real hydroclimate progression toward greater glacial aridity. International Ocean Discovery Program Expeditions 356, 363, and 369 (conducted in 2015, 2016, and 2017, respectively) recovered extensive sedimentary climate archives off Australia. Ongoing analyses of these strata reveal a marine record of the onset of continental aridity as Australia migrated northward by 25° over the last 50 million years. These Southern Hemisphere oceanic records will continue to yield key information on global climate evolution, allowing us to understand how deserts and monsoonal systems have evolved through time. [ABSTRACT FROM AUTHOR]

Phylogeographic studies around the world have identified refugia where fauna were able to persist during unsuitable climatic periods, particularly during times of glaciation. In Australia the effects of Pleistocene climate oscillations on rainforest taxa have been well studied but less is known about the effects on mesic-habitat fauna, such as the eastern grey kangaroo (Macropus giganteus). The eastern grey kangaroo is a large mammal that is common and widespread throughout eastern Australia, preferring dry mesic habitat, rather than rainforest. As pollen evidence suggests that the central-eastern part of Australia (southeast Queensland and northern New South Wales) experienced cycles of expansion in mesic habitat with contraction in rainforests, and vice versa during glacial and interglacial periods, respectively, we hypothesise that the distribution of the eastern grey kangaroo was affected by these climate oscillations and may have contracted to mesic habitat refugia. From 375 mitochondrial DNA control region sequences from across the distribution of eastern grey kangaroos we obtained 108 unique haplotypes. Phylogenetic analysis identified two clades in Queensland, one of which is newly identified and restricted to a small coastal region in southern Queensland north of Brisbane, known as the Sunshine Coast. The relatively limited geographic range of this genetically isolated clade suggests the possibility of a mesic habitat refugium forming during rainforest expansion during wetter climate cycles. Other potential, although less likely, reasons for the genetic isolation of the highly distinct clade include geographic barriers, separate northward expansions, and strong local adaptation. [ABSTRACT FROM AUTHOR]

Although Earth is widely believed to have undergone a series of extreme low-latitude snowball glaciations during the Neoproterozoic (ca. 1000-543 Ma), only one reliable pa- leomagnetic result, from Elatina, South Australia, places glacial rocks close to the equator. We report new paleomagnetic data from the Neoproterozoic Huqf Supergroup of Oman that pass fold and reversal tests and yield a paleopole at 52.3°S, 074.4°E (N = 25 sites; α95 = 7.3°). This paleopole places the Muscat region of Oman at a latitude of 13° in the late Neoproterozoic and provides the first direct evidence that both glacial and overlying cap carbonate units were deposited in the tropics. The presence of glacial-interglacial cyclicity within the Huqf Supergroup indicates that areas close to the equator may have been largely free of ice at the time of deposition, a result that is inconsistent with the classic snowball Earth model. Our result precludes the possibility that contrasting lithologies mark a phase of rapid plate motion and provides the first evidence for low-latitude glaciation in Arabia. A series of magnetic reversals in the Fiq tillite and the overlying Had ash dolomite, in northern and central Oman, correlates well with a similar sequence in the Mirbat Formation in southern Oman and indicates that recovery from glacial conditions took place over long time scales (possibly >105_106 yr). [ABSTRACT FROM AUTHOR]

International Ocean Discovery Program (IODP) Expedition 356 Site U1461 represents one of the few records from the North West Australian shelf that provides information about aridity fluctuations in Australia during the Quaternary. A combination of chronostratigraphic indicators revealed the (partial) preservation of two major glaciations (Marine Isotope Stage (MIS) 2 and MIS 12) in the sedimentary record. The faunal content (mainly benthic foraminifera, corals and bryozoans) was analyzed to estimate paleo-environments and paleo-depths in order to determine if these sediments have been remobilized by reworking processes. Despite the occurrence of a depositional hiatus (including MIS 5d to MIS 9-time interval), the excellent preservation of faunal content suggests that the preserved sediment is in situ. The geochemical composition of the sediments (Nd and major elements) indicates that during MIS 12 riverine input was likely reduced because of enhanced aridity, and the sediment provenance (mainly atmospheric dust) is likely in the central (Lake Eyre) or eastern (Murray Darling Basin) parts of the Australian continent. MIS 2 is confirmed to be one of the driest periods recorded in Australia but with mixed dust sources from the eastern and western parts of the continent. More humid conditions followed the glacial maximum, which might correspond to the peak of the Indian-Australian Summer Monsoon. [ABSTRACT FROM AUTHOR]

Marine Isotope Stage 2 (MIS 2) is the latest glacial period and includes the Last Glacial Maximum, which is known as the period when global ice volume reached its maximum and global temperature lower than today. An advantage of MIS 2 is the availability of radiocarbon dating to make it possible to compare sea-level data with other paleoclimatic proxies. However, the number and accuracy of sea-level records during MIS 2 is currently lacking. Here we present the history of MIS 2 sea-level and ice-sheet change as recorded in the Bonaparte Gulf, northwestern Australia, by reconstructing relative sea level and then modeling glacial isostatic adjustment. The isostatically-corrected global sea-level history indicates that sea-level plateaued around 23 cal kyr BP prior reaching its minimum (~19 cal kyr BP). These large changes in ice volume over such a short time indicates that the continental ice sheets never reached their isostatic equilibrium during the Last Glacial Maximum. [ABSTRACT FROM AUTHOR]