School of Earth Sciences - Research Publications
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ItemCommuter lives: a review symposium on David Bissell's Transit Life(WILEY, 2020-02-01)Abstract This article presents a series of commentaries on Transit Life: How Commuting is Transforming Our Cities, published by MIT Press in 2018. Centring on an in—depth case study of Sydney, the book argues the need to attend carefully to the fine—grained detail of the commuting experience. In all sorts of ways, Transit Life presents a way of thinking about urban transportation radically different from that used by mainstream transport planners and geographers. Geographical Research asked six researchers—Tim Edensor, Michele Lobo, Debbie Hopkins, Helen Fitt, Juliana Mansvelt, and Donald McNeill—to reflect on what kind of research vistas might be opened up bring the tools of cultural geography and mobility research to the world of commuting. Here are their responses, rounded out by a reply by David Bissell, Transit Life's author.
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ItemWhen food regimes become hegemonic: Agrarian India through a Gramscian lens(WILEY, 2019-09-11)Abstract The concept of food regimes, as developed by Friedmann and McMichael, has proven useful in analysing how systems of food production, distribution, and consumption are linked to cycles of global capital accumulation and identifying the contradictions and conflicts that underlie them. A question that food regime analysis is relatively less able to address, however, is how food regimes become established and endure with the apparent acquiescence of those who are the victims of their contradictions and inequities. In this paper, I argue that a deeper engagement with Gramsci's theory of hegemony may help to address this lacuna in food regime analysis. To illustrate my case, I draw on studies of rural India from the colonial period to the present day, highlighting the ways in which the hegemonic mechanisms of consent and coercion have been crucial to the consolidation of each of the three food regimes identified by Friedmann and McMichael.
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ItemResettlement and the environment in Vietnam: Implications for climate change adaptation planning(WILEY, 2019-08)Increasingly the environment, and climate risks in particular, are influencing migration and planned resettlement in Vietnam, raising the spectre of increased displacement in a country already confronting serious challenges around sustainable land and water use as well as urbanisation. Planned resettlement has emerged as part of a suite of measures being pursued as part of disaster risk reduction and climate change adaptation strategies. This paper provides an historical, political, legal and environmental overview of resettlement in Vietnam identifying key challenges for framing resettlement as climate change adaptation. The paper outlines the scale of past resettlement in Vietnam, identifying the drivers and implications for vulnerability. Detailed case studies of resettlement are reviewed. Through this review, the paper reflects on the growing threat of climate change and the likelihood of increased displacement associated with worsening climate risks to identify some critical considerations for planned resettlement in climate change adaptation planning.
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ItemDisoriented geographies: Undoing relations, encountering limits(WILEY, 2019-12)This paper develops the concept of disorientation as a constitutive but overlooked dimension of mobile life, and it explores the significance of disorientation for geographical thought. Conceptually, the paper argues that disorientation is a productive geographical concept for acknowledging how, at times, bodies can lose their orienting relations to other bodies, to actions, and to situations. These losses are explored through the themes of incomprehension, confusion, and disintegration, respectively. Substantively, through research with mobile worker households in Australia, the paper expands our understanding of geographies of mobility by interrogating non‐traditional but increasingly common living scenarios created by intensified mobility. Methodologically, the paper develops a narrative approach to presenting the richly complex experiences of “left behind” mobile worker partners through impressionistic interview portraits. Disciplinarily, contributing to ongoing debates in geography on relationality and encounter, the paper provides a counterbalance to the dominant focus on relation construction, and it opens up space for thinking differently about what, exactly, is being encountered in disorienting experiences.
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ItemObserved Relationships Between Sudden Stratospheric Warmings and European Climate Extremes(AMER GEOPHYSICAL UNION, 2019-12-27)Abstract Sudden stratospheric warmings (SSWs) have been linked with anomalously cold temperatures at the surface in the middle to high latitudes of the Northern Hemisphere as climatological westerly winds in the stratosphere tend to weaken and turn easterly. However, previous studies have largely relied on reanalyses and model simulations to infer the role of SSWs on surface climate and SSW relationships with extremes have not been fully analyzed. Here, we use observed daily gridded temperature and precipitation data over Europe to comprehensively examine the response of climate extremes to the occurrence of SSWs. We show that for much of Scandinavia, winters with SSWs are on average at least 1 °C cooler, but the coldest day and night of winter is on average at least 2 °C colder than in non‐SSW winters. Anomalously high pressure over Scandinavia reduces precipitation on the northern Atlantic coast but increases overall rainfall and the number of wet days in southern Europe. In the 60 days after SSWs, cold extremes are more intense over Scandinavia with anomalously high pressure and drier conditions prevailing. Over southern Europe there is a tendency toward lower pressure, increased precipitation and more wet days. The surface response in cold temperature extremes over northwest Europe to the 2018 SSW was stronger than observed for any SSW during 1979–2016. Our analysis shows that SSWs have an effect not only on mean climate but also extremes over much of Europe. Only with carefully designed analyses are the relationships between SSWs and climate means and extremes detectable above synoptic‐scale variability.
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ItemPost Gondwana breakup evolution of the SE Australia rifted margin revisited(WILEY, 2019-12-16)Abstract Low‐temperature thermochronology (LTT) is commonly used to investigate onshore records of continental rifting and geomorphic evolution of passive continental margins. The SE Australian passive margin, like many others, has an elevated plateau separated from the coastal plain by an erosional escarpment, presumed to originate through Cretaceous rifting prior to Tasman Sea seafloor spreading. Previous LTT studies have focused on reconciling thermal histories with development of the present‐day topography. New apatite LTT data along an escarpment‐to‐coast transect define a classic “boomerang” (mean track length vs. fission‐track age), indicating variable overprinting of late‐Palaeozoic cooling ages by a younger, mid‐Cretaceous cooling event. Regionally, however, the boomerang trend diverges NNW away from the coast and crosses the escarpment, implying the underlying thermal history pre‐dates escarpment formation and is largely independent from post‐breakup landscape evolution. We suggest that Cretaceous cooling might relate to erosion of Permo‐Triassic sedimentary cover from a formerly more extensive Sydney Basin.
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ItemMining modification of river systems: A case study from the Australian gold rush(WILEY, 2020-04-09)Abstract Mobilisation of large volumes of bedrock, regolith and soil has long been a characteristic feature of metal mining. Before the 20th century this was most efficiently achieved through harnessing the motive power of water. Large‐scale water use in mining produced waste sands, gravels and silts that were flushed downstream, triggering changes in stream and floodplain morphology and function. During the 19th century the shift from artisanal to industrialised mining resulted in a rapid increase in the scale and extent of environmental change. This paper presents results from a multidisciplinary research programme investigating the environmental effects of 19th‐century gold mining on waterways in south‐eastern Australia. Archaeological and geospatial landscape survey are combined with historical data modelling and geomorphological analysis to examine the extractive processes that produced sediment in headwater regions and how this influenced fluvial processes operating on downstream waterways and floodplains. Our case study of the Three Mile‐Hodgson Creek system on the Ovens (Beechworth) goldfield in north‐east Victoria indicates that miners mobilised up to 7.3 million m3 of sediment in this small catchment alone. Results of the research suggest that tailings dams and sludge channels in this catchment are important archaeological evidence for early attempts to manage industrial waste.
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ItemLate Miocene Hinterland Crustal Shortening in the Longmen Shan Thrust Belt, the Eastern Margin of the Tibetan Plateau(AMER GEOPHYSICAL UNION, 2019-11-13)Abstract Long‐term (million year time scale) fault‐slip history is crucial for understanding the processes and mechanisms of mountain building in active orogens. Such information remains elusive in the Longmen Shan, the eastern Tibetan Plateau margin affected by the devastating 2008 Wenchuan earthquake. While this event drew attention to fault deformation on the foreland side (the Yingxiu‐Beichuan fault), little is known about the deformation history of the hinterland Wenchuan‐Maoxian fault. To address this gap, thermochronological data were obtained from two vertical transects from the Xuelongbao massif, located in the hanging wall of the Wenchuan‐Maoxian fault. The data record late Miocene rapid cooling and rock exhumation at a rate of 0.9–1.2 km/m.y. from ~13 Ma to present. The exhumation rate is significantly higher than that in the footwall (~0.3–0.5 km/m.y.), indicating a differential exhumation of ~0.6 km/m.y. across the fault. This differential exhumation provides the first and minimum constraint on the long‐term throw rate (~0.6 km/m.y) of the Wenchuan‐Maoxian fault since the late Miocene. This new result implies continuous crustal shortening along the hinterland fault of Longmen Shan, even though it has not been ruptured by major historic earthquakes. Our study lends support to geodynamic models that highlight crustal shortening as dominating deformation along the eastern Tibetan Plateau.
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ItemThe Impact of a Very Weak and Thin Upper Asthenosphere on Subduction Motions(AMER GEOPHYSICAL UNION, 2019-11-11)Abstract Recent geophysical observations report the presence of a very weak and thin upper asthenosphere underneath subducting oceanic plates at convergent margins. Along these margins, trench migrations are significantly slower than plate convergence rates. We use numerical models to assess the role of a weak upper asthenospheric layer on plate and trench motions. We show that the presence of this layer alone can enhance an advancing trend for the motion of the plate and hamper trench retreat. This mechanism provides a novel and alternative explanation for the slow rates of trench migration and fast‐moving plates observed globally at natural subduction zones.
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ItemObserved and projected intra-seasonal variability of Australian monsoon rainfall(Wiley, 2020-03-30)Indices derived from daily rainfall time series are used to measure “burst” features of the northern Australia monsoon, corresponding to one or more days of heavy rainfall. These indices include number of burst days, numbers and durations of burst events, and average intensity. The results using observational data show how these features can vary from one year to the next, and how they can vary from the station scale (Darwin) to the regional scale (northern Australia). The results from Coupled Model Intercomparison Project Phase 5 (CMIP5) climate model simulations under both historical and future greenhouse gas conditions have also been analysed and indicate how well models can capture these features and how they might change by the end of the 21st century under a high emissions scenario. While most models provide a reasonable simulation of present‐day burst features, there is little consensus for a significant change to seasonal rainfall totals when looking at the full CMIP5 ensemble. A subset of models with detectable skills with respect to the Madden‐Julian Oscillation shows evidence for an increase in the seasonal total rainfall amount and most other monsoon metrics, except a slight decrease in the number of burst events. This is consistent with a basic thermodynamic response to warming and consistent with findings elsewhere. However, the Australian monsoon is strongly influenced by the large‐scale circulation and there remains some doubt about whether we can confidently diagnose all the changes to monsoon bursts that could occur given the limited ability of many of the current generation of models to simulate tropical cyclones, the Madden‐Julian Oscillation and other relevant features.