School of Earth Sciences - Research Publications
Now showing items 1-12 of 344
Causal knowledge promotes behavioral self-regulation: An example using climate change dynamics
(PUBLIC LIBRARY SCIENCE, 2017-09-07)
Adopting successful climate change mitigation policies requires the public to choose how to balance the sometimes competing goals of managing CO2 emissions and achieving economic growth. It follows that collective action on climate change depends on members of the public to be knowledgeable of the causes and economic ramifications of climate change. The existing literature, however, shows that people often struggle to correctly reason about the fundamental accumulation dynamics that drive climate change. Previous research has focused on using analogy to improve people's reasoning about accumulation, which has been met with some success. However, these existing studies have neglected the role economic factors might play in shaping people's decisions in relation to climate change. Here, we introduce a novel iterated decision task in which people attempt to achieve a specific economic goal by interacting with a causal dynamic system in which human economic activities, CO2 emissions, and warming are all causally interrelated. We show that when the causal links between these factors are highlighted, people's ability to achieve the economic goal of the task is enhanced in a way that approaches optimal responding, and avoids dangerous levels of warming.
Letting the 'cat' out of the bag: pouch young development of the extinct Tasmanian tiger revealed by X-ray computed tomography
(ROYAL SOC, 2018-02-01)
The Tasmanian tiger or thylacine (Thylacinus cynocephalus) was an iconic Australian marsupial predator that was hunted to extinction in the early 1900s. Despite sharing striking similarities with canids, they failed to evolve many of the specialized anatomical features that characterize carnivorous placental mammals. These evolutionary limitations are thought to arise from functional constraints associated with the marsupial mode of reproduction, in which otherwise highly altricial young use their well-developed forelimbs to climb to the pouch and mouth to suckle. Here we present the first three-dimensional digital developmental series of the thylacine throughout its pouch life using X-ray computed tomography on all known ethanol-preserved specimens. Based on detailed skeletal measurements, we refine the species growth curve to improve age estimates for the individuals. Comparison of allometric growth trends in the appendicular skeleton (fore- and hindlimbs) with that of other placental and marsupial mammals revealed that despite their unique adult morphologies, thylacines retained a generalized early marsupial ontogeny. Our approach also revealed mislabelled specimens that possessed large epipubic bones (vestigial in thylacine) and differing vertebral numbers. All of our generated CT models are publicly available, preserving their developmental morphology and providing a novel digital resource for future studies of this unique marsupial.
Consumption and exchange in Early Modern Cambodia: NAA of brown-glaze stoneware from Longvek, 15th-17th centuries.
(Public Library of Science (PLoS), 2019)
An evaluation of the geochemical characteristics of 102 storage jar sherds by k0-neutron activation analysis (k0-NAA) from archaeological contexts in Cambodia and reference samples from stoneware production centres in Thailand provides a new perspective on regional and global trade in mainland Southeast Asia. Identification of seven geochemical groups enables distinctions between production centres, and articulation of their role in trade between northern and central Thailand, South China and Cambodia. Storage jars from Thailand and South China are known in archaeological contexts worldwide because of their durability and intrinsic functional and cultural values. Evidenced by a novel application of k0-NAA, analogous stoneware sherds at Longvek connect the Cambodian capital to a global trading network. Additional proof of ceramics from an undocumented Cambodian kiln demonstrates the gradual and complex transition between the Angkorian past and the Early Modern period.
Microbial composition analyses by 16S rRNA sequencing: A proof of concept approach to provenance determination of archaeological ochre
(PUBLIC LIBRARY SCIENCE, 2017-10-18)
Many archaeological science studies use the concept of "provenance", where the origins of cultural material can be determined through physical or chemical properties that relate back to the origins of the material. Recent studies using DNA profiling of bacteria have been used for the forensic determination of soils, towards determination of geographic origin. This manuscript presents a novel approach to the provenance of archaeological minerals and related materials through the use of 16S rRNA sequencing analysis of microbial DNA. Through the microbial DNA characterization from ochre and multivariate statistics, we have demonstrated the clear discrimination between four distinct Australian cultural ochre sites.
Palynological-age determination of Early Cretaceous vertebrate-bearing beds along the south Victorian coast of Australia, with implications for the spore-pollen biostratigraphy of the region
(Taylor & Francis, 2020)
Palynology is used to provide new age controls for the coastal exposures yielding Early Cretaceous vertebrate faunas in the Otway and Gippsland basins, southeast Australia. This work shows all vertebrate-bearing deposits in the Otway Basin are Albian in age. On the eastern margin of Cape Otway, vertebrate-bearing deposits are attributed to the early Albian Crybelosporites striatus Zone, except for one in the younger Coptospora paradoxa Zone. To the west of Cape Otway, the sampled deposits range from the oldest zone in the Albian, the C. striatus Zone, to the C. paradoxa and Phimopollenites pannosus zones, providing a complete section of the Albian stage. In the Gippsland Basin, the structural setting of vertebrate deposits is more complicated and large portions of the coastal exposures consist of repeated sections controlled by small-scale faults. Sites in this region lie below or above the Barremian/Aptian boundary. However, owing to the paucity of age indicator species, some sampled deposits remain undated. In this basin, the ranges of certain key palynomorph species (e.g., Pilosisporites notensis and Pilosisporites parvispinosus) differed from those outlined in some previously published biostratigraphic schemes. The discovery of the angiosperm pollen Clavatipollenites hughesii in the lowermost Aptian deposits of the Gippsland Basin is consistent with its first occurrence elsewhere in Australia and shows it is a reliable indicator for the Aptian stage. This study shows that there is currently a collection bias towards vertebrate assemblages that are latest Barremian and early Albian in age.
A multi-hazards earth science perspective on the COVID-19 pandemic: the potential for concurrent and cascading crises.
(Springer Science and Business Media LLC, 2020-05-16)
Meteorological and geophysical hazards will concur and interact with coronavirus disease (COVID-19) impacts in many regions on Earth. These interactions will challenge the resilience of societies and systems. A comparison of plausible COVID-19 epidemic trajectories with multi-hazard time-series curves enables delineation of multi-hazard scenarios for selected countries (United States, China, Australia, Bangladesh) and regions (Texas). In multi-hazard crises, governments and other responding agents may be required to make complex, highly compromised, hierarchical decisions aimed to balance COVID-19 risks and protocols with disaster response and recovery operations. Contemporary socioeconomic changes (e.g. reducing risk mitigation measures, lowering restrictions on human activity to stimulate economic recovery) may alter COVID-19 epidemiological dynamics and increase future risks relating to natural hazards and COVID-19 interactions. For example, the aggregation of evacuees into communal environments and increased demand on medical, economic, and infrastructural capacity associated with natural hazard impacts may increase COVID-19 exposure risks and vulnerabilities. COVID-19 epidemiologic conditions at the time of a natural hazard event might also influence the characteristics of emergency and humanitarian responses (e.g. evacuation and sheltering procedures, resource availability, implementation modalities, and assistance types). A simple epidemic phenomenological model with a concurrent disaster event predicts a greater infection rate following events during the pre-infection rate peak period compared with post-peak events, highlighting the need for enacting COVID-19 counter measures in advance of seasonal increases in natural hazards. Inclusion of natural hazard inputs into COVID-19 epidemiological models could enhance the evidence base for informing contemporary policy across diverse multi-hazard scenarios, defining and addressing gaps in disaster preparedness strategies and resourcing, and implementing a future-planning systems approach into contemporary COVID-19 mitigation strategies. Our recommendations may assist governments and their advisors to develop risk reduction strategies for natural and cascading hazards during the COVID-19 pandemic.
Geodynamic benchmarking tests in HPC
(Australian Partnership for Advanced Computing, 2005)
The increase in large science focused computational frameworks has raised many issues involving the ability to maintain accurate scientific benchmarks throughout the ongoing evolution of the code. These science based tests allow not only developers access to the latest updates, but the science users as well. It is these scientific tests required for geodynamic code benchmarking in a HPC environment that are investigated. The importance of benchmarking in computational science, for both quality assurance and reliability, is discussed and a case study for thermochemical convection modelling is presented. The implementation of automated testing for science units is described with particular attention to the problems arising from science tests compared to traditional computational tests.
Eocene to Oligocene high paleolatitude neritic record of Oi-1 glaciation in the Otway Basin southeast Australia
Multiple stable isotope investigations from upper Eocene to lower Oligocene deep-water marine sequences record the transition from global greenhouse to the icehouse conditions (Oi-1 glacial). While Southern Ocean high latitude deep sea records of this transition are well known, their shallow marine equivalents are rare and have the potential to record the eustatic and oceanic consequences of Paleogene glacial variability. The well-known high paleolatitude (~55°S) neritic carbonate sequence at Browns Creek and Castle Cove in the Otway Basin in southeast Australia spans the Eocene-Oligocene boundary. During this time the area lay on the northeastern margin of the Australo-Antarctic Gulf facing the evolving Southern Ocean. The importance of this record has been hampered by a lack of a consistent stratigraphy and contradictory microfossil interpretations. To reconcile these issues we combine new bio-, chemo- and lithostratigraphic analyses of the outcrops and a new core (Colac- 2) with pre-existing data to revise the stratigraphy. This confirms the middle/upper Eocene boundary is near the base of the section. The overlying upper Eocene siliciclastic strata are truncated by an unconformity (of ~0.8 Ma in duration) and overlain by glauconitic sand (the Notrostrea greensand) deposited after ~35.9 Ma. Subsequently deepening to middle to outer neritic depths deposited cyclic carbonates. Shallowing after ~35 Ma deposited laterally variable calcareous siliciclastic facies. These strata were tilted and eroded prior to 34 Ma leading to shallow water facies that may have been subaerially exposed during uplift. Brachiopod strontium isotope dates and an 0.5‰ carbon isotope excursion above this unconformity suggests the top of the Browns Creek and the base of the Castle Cove section correlate to Eocene-Oligocene transition (EOT-1) at ~34 Ma. The subsequent persistence of positive C/O isotope values above this level records the transition to the Oi-1 glaciation at ~33.7 Ma. Strong cyclicity in the inner shelf Castle Cove limestone is interpreted to record the commencement of obliquity dominated glacio-eustacy during the Oi-1 glacial phase. The shallowing from outer to inner shelf palaeodepths from the late Eocene to the early Oligocene is likely related to the onset of cryosphere expansion, however, palaeodepth estimates are complicated by the onset of regional compressional tectonism at the Eocene/Oligocene boundary that caused localized tilting and an unconformity with possible antisiphoning effects in this near-field site.
A global analysis of urban design types and road transport injury: an image processing study.
BACKGROUND: Death and injury due to motor vehicle crashes is the world's fifth leading cause of mortality and morbidity. City and urban designs might play a role in mitigating the global burden of road transport injury to an extent that has not been captured by traditional safe system approaches. We aimed to determine the relationship between urban design and road trauma across the globe. METHODS: Applying a combined convolutional neural network and graph-based approach, 1692 cities capturing one third of the world's population were classified into types based on urban design characteristics represented in sample maps. Associations between identified city types, characteristics contained within sample maps, and the burden of road transport injury as measured by disability adjusted life-years were estimated through univariate and multivariate analyses, controlling for the influence of economic activity. FINDINGS: Between Mar 1, 2017, and Dec 24, 2018, nine global city types based on a final sample of 1632 cities were identified. Burden of road transport injury was an estimated two-times higher (risk ratio 2·05, 95% CI 1·84-2·27) for the poorest performing city type compared with the best performing city type, culminating in an estimated loss of 8·71 (8·08-9·25) million disability-adjusted life-years per year attributable to suboptimal urban design. City types that featured a greater proportion of railed public transport networks combined with dense road networks characterised by smaller blocks showed the lowest rates of road traffic injury. INTERPRETATION: This study highlights the important role that city and urban design plays in mitigating road transport injury burden at a global scale. It is recommended that road and transport safety efforts promote urban design that features characteristics inherent in identified high-performance city types including higher density road infrastructure and high rates of public transit. FUNDING: See acknowledgments.
Gravity Wave Influences On Mesoscale Divergence: An Observational Case Study
(American Geophysical Union, 2020-01-16)
Characteristics of tropospheric low-frequency gravity waves are diagnosed in radiosonde soundings from the TropicalWarm Pool-International Cloud Experiment near Darwin, Australia. The waves have typical vertical wavelengths of about 4 km, horizontal wavelengths of about 600 km, and intrinsic periods of about 12 hr. These scales match those of the vertical, horizontal, and temporal variability found in area-averaged horizontal wind divergence over the same domain. Vertical profiles of divergence show wave-like structures with variability of the order of 2 × 10−5 s−1 in the free troposphere. The results for Darwin are similar to previously reported observed mesoscale patterns of divergence/convergence over the tropical Atlantic. The findings imply that tropical divergence on spatial scales of a few hundred kilometers, which is known to influence the organization of convection, may be forced by gravity waves.
Speleothem growth intervals reflect New Zealand montane vegetation response to temperature change over the last glacial cycle.
(Springer Nature, 2020-02-12)
Flowstone speleothem growth beneath Mount Arthur, New Zealand shows a clear relationship to vegetation density and soil development on the surface above. Flowstone does not currently form beneath sub-alpine Nothofagus forest above ca. 1000-1100 m altitude but U-Th dating shows it has formed there during past intervals of warmer-than-present conditions including an early-mid Holocene optimum and the last interglacial from ca. 131-119 ka. Some flowstones growing beneath ca. 600 m surface altitude, currently mantled with dense broadleaf-podocarp forest, grew during full glacial conditions, indicating that local tree line was never below this altitude. This implies that Last Glacial Maximum annual temperature was no more than ca. 4 °C cooler than today. Flowstone growth appears to be a robust indicator of dense surface vegetation and well-developed soil cover in this setting, and indicates that past interglacial climates of MIS 7e, 5e, the early-mid Holocene and possibly MIS 5a were more conducive to growth of trees than was the late Holocene, reflecting regional temperature changes similar in timing to Antarctic temperature changes. Here, flowstone speleothem growth is a sensitive indicator of vegetation density at high altitude, but may respond to other factors at lower altitudes.