Recent publications in Geoscience

Rasalam, R., Bandaranaike, S., and Anushka, K. (2019) Bridging the gap in health professionals from novice to advanced practitioner: a practical framework. In: Abstracts from the 16th Asia Pacific Medical Education Conference. p. 124. From: APMEC 2019: 16th Asia Pacific Medical Education Conference, 9-13 January 2019, Singapore.
The objective of the AHCD was to facilitate the successful transition of an allied health professional from novice to advanced practitioner while focussing on key competencies and levels of autonomy through reflective practice and emotional and social sensitivity to the workplace. The AHCD facilitates this transition via self-directed learning and reflective practice. The philosophy presented in the framework may be applicable to all health care professionals.

Tavares, Silvia G., Swaffield, Simon R., and Stewart, Emma J. (2019) A case-based methodology for investigating urban comfort through interpretive research and microclimate analysis in post-earthquake Christchurch, New Zealand. Environment and Planning B: Urban Analytics and City Science, 46 (4). pp. 731-750.
This paper explores how an interpretive case-based research strategy can reveal new empirical and theoretical insights into microclimate design. Innovative fieldwork in Christchurch, New Zealand investigated the nature and social meanings of urban comfort in a city with a seasonal climate featuring microclimatic variability, and with a physical landscape undergoing rapid change following a series of major earthquakes. Ethnographic methods were combined with microclimate measurements in four Christchurch-based case study locations to identify ways in which people adjust their cultural and lifestyle values and expectations to the actual microclimatic conditions. The field investigation had to capture data relevant to the microclimatic variability and be suitable for rapidly changing urban settings. Results suggest this integrative methodology successfully adapts to challenging physical contexts, and is able to provide a coherent body of evidence. Important insights revealed through this methodology may not have become apparent if only conventional microclimate methods were used.

Barrios-Garrido, H., Wildermann, N., Diedrich, A., and Hamann, M. (2019) Conflicts and solutions related to marine turtle conservation initiatives in the Caribbean basin: identifying new challenges. Ocean and Coastal Management, 171. pp. 19-27.
Conflicts among and between local, national, regional and international stakeholders involved in marine turtle conservation are increasing. Often, they arise because of different socio-economic backgrounds of the people or groups involved. Here, we identified and assessed the conservation-based conflicts occurring in 24 of the 39 Caribbean countries, including their frequency, level of severity, number of stakeholders' groups involved, the degree to which they hinder conservation goals, and potential solutions. Using a cross-sectional social survey, we evaluated the presence and details of conservation conflicts provided by 72 respondents. The respondents included conservation-based project leaders, researchers, people involved in policy-based decision-making, conservation volunteers (community-based conservation groups), and species experts with experience working on marine turtle conservation programs in the Caribbean. The respondents identified 136 conflicts, and we grouped them into 16 different categories. The most commonly mentioned causes of conflicts were: 1) the ‘lack of enforcement by local authorities to support conservation-based legislation or programs’ (18%); 2) ‘legal consumption of turtles by one sector of community clashing the conservation aspirations of other sectors of community (14%); and 3) ’variable enforcement of legislation to limit/prohibit use across range states of the species (10%). From our data it is also apparent that illicit activities in the region are also likely to impact the future success of conservation or monitoring based projects and programs. Overall, an exhaustive review was carried out, and the potential solutions were gathered. Due to the level of severity (physical violence) that some conflicts have reached, achieving solutions will be challenging without mediation, mutual cooperation around shared values, and adaptive management arrangements. Achieving this will require combinations of bottom up and top down collaborative governance approaches.

Mizrahi, Me'ira, Duce, Stephanie, Pressey, Robert L., Simpfendorfer, Colin A., Weeks, Rebecca, and Diedrich, Amy (2019) Global opportunities and challenges for shark large marine protected areas. Biological Conservation, 234. pp. 107-115.
Legislation to ban the targeted fishing of sharks is frequently employed within developing coastal nations. These Shark Large Marine Protected Areas (SLMPAs) are established primarily to alleviate the direct threats that humans pose to sharks through activities such as overfishing and destructive fishing practices. However, despite the anthropogenic nature of these threats, socioeconomic factors are often given less consideration than their ecological counterparts when designating SLMPAs. In this paper, we identified and examined relevant national-level socioeconomic data to determine the challenges and opportunities associated with implementing SLMPAs, focussing on least developed and low income countries. We aimed to use these socioeconomic data to identify nations where SLMPAs are more likely to be successful in providing conservation benefits to sharks. We used principal component analysis to develop two national-level indices that represent these anticipated opportunities and challenges for implementing SLMPAs across 87 coastal nations. The Opportunity Index identifies those nations in which socioeconomic conditions such as adaptive capacity, and strong and fair governance, are favourable for SLMPAs to provide conservation benefits to sharks. The Challenge Index identifies those nations that may not yet be in a position developmentally to support communities to adapt to a loss of access to resources associated with SLMPAs, or to manage and enforce broad scale restrictive legislation. In combination with biophysical considerations, the Challenge and Opportunity indices presented here can support policy makers in deciding whether, and in what cases, SLMPAs are the most appropriate measure to provide conservation benefits to sharks.

Diedrich, Amy, Benham, Claudia, Pandihau, Lina, and Sheaves, Marcus (2019) Social capital plays a central role in transitions to sportfishing tourism in small-scale fishing communities in Papua New Guinea. Ambio, 48 (4). pp. 385-396.
Growing concerns about pressures of global change on small-scale fishing communities have resulted in a proliferation of livelihood diversification initiatives linked to tourism. Where the focus is often on the role of financial, physical, and human capital in influencing the uptake of new opportunities, we argue for more consideration of the role of social capital. We implemented 157 household-level surveys in small-scale fishing communities in Papua New Guinea and modelled the influence of social and other capital assets on people’s perceptions of how easy it would be to become involved in sportfishing tourism. Social capital had a stronger influence relative to other forms of capital, with perceptions of reciprocity and satisfaction with leadership being the most influential aspects. Based on these results, we stress the importance of developing strategies aimed at understanding, building, and maintaining social capital and related social dynamics when implementing livelihood diversification initiatives.

Mizrahi, Me'ira, Diedrich, Amy, Weeks, Rebecca, and Pressey, Robert L. (2019) A systematic review of the socioeconomic factors that influence how marine protected areas impact on ecosystems and livelihoods. Society and Natural Resources, 32 (1). pp. 4-20.
Marine protected areas (MPAs) are among the most widely accepted methods of marine management. MPAs are not, however, always placed such that they can maximize impact on conservation and livelihoods. Current MPA guidelines fall short in focusing primarily on biophysical criteria, overlooking interrelated socioeconomic factors. We identified 32 socioeconomic factors that influence whether MPA placement has an impact on biodiversity and/or livelihoods and weighted the quality of evidence using a novel “Evidence for Impact” Score. Results suggest that stakeholder engagement, poverty, population density, and strong leadership have most potential to positively impact biodiversity and/or livelihoods, but the direction of impact (i.e., positive or negative) can be context-dependent. We found a generally poor evidence base for impact evaluation of socioeconomic factors: though some factors were highly cited, few studies actually evaluate impact. Results indicate the need for a more interdisciplinary approach to MPA placement and more empirical studies that assess impact.

Abu Sharib, Ahmed S.A.A., Maurice, Ayman E., Abd El-Rahman, Yasser M., Sanislav, Ioan V., Schulz, Bernhard, and Bakhit, Bottros R. (2019) Neoproterozoic arc sedimentation, metamorphism and collision: evidence from the northern tip of the Arabian-Nubian Shield and implication for the terminal collision between East and West Gondwana. Gondwana Research, 66. pp. 13-42.
In the Wadi Um Had area, Central Eastern Desert, Egypt, NE-trending metapelitic and molasse-type successions are exposed. The metasediments bear the geochemical signature of a first depositional cycle in two distinct continental island arc settings that derived from incipiently-to moderately-weathered intermediate to felsic sources under generally warm and humid conditions. The metapelitic succession records three distinct episodes of metamorphism, M1–M3, whereas the molasse-type succession records only the last metamorphic episode, M3. M1/D1 records an amphibolite facies tectono-metamorphic event that has been dated at 625 ± 5 Ma, whereas M2/D2 records a greenschist facies subduction-related event. Collision of the two domains during a NE–SW shortening D3, culminated in formation of the macroscopic NW–SE-trending folds. D2 and D3 correlate with the gneiss-forming event, which is constrained at <609 Ma, and doming of the nearby Meatiq gneiss dome, respectively. M3 is a hornblende hornfels facies thermal metamorphism related to the intrusion of the post-orogenic, Neoproterozoic (596.3 Ma) Um Had granite. This study records, for the first time, a tectono-metamorphic phase predating the gneiss-forming event in the Meatiq gneiss dome, and pushes the boundary of the Late Ediacaran terminal collision between East and West Gondwana to ≤600 Ma.

Holm, Robert J., Tapster, Simon, Jelsma, Hielke A., Rosenbaum, Gideon, and Mark, Darren F. (2019) Tectonic evolution and copper-gold metallogenesis of the Papua New Guinea and Solomon Islands region. Ore Geology Reviews, 104. pp. 208-226.
Papua New Guinea and the Solomon Islands are in one of the most prospective regions for intrusion-related mineral deposits. However, because of the tectonic complexity of the region and the lack of comprehensive regional geological datasets, the link between mineralization and the regional-scale geodynamic framework has not been understood. Here we present a new model for the metallogenesis of the region based on a synthesis of recent studies on the petrogenesis of magmatic arcs and the history of subduction zones throughout the region, combined with the spatio-temporal distribution of intrusion-related mineral deposits, and six new deposit ages. Convergence at the Pacific-Australia plate boundary was accommodated, from at least 45 Ma, by subduction at the Melanesian trench, with related Melanesian arc magmatism. The arrival of the Ontong Java Plateau at the trench at ca. 26 Ma resulted in cessation of subduction, immediately followed by formation of Cu-Au porphyry-epithermal deposits (at 24-20 Ma) throughout the Melanesian arc. Late Oligocene to early Miocene tectonic reorganization led to initiation of subduction at the Pocklington trough, and onset of magmatism in the Maramuni arc. The arrival of the Australian continent at the Pocklington trough by 12 Ma resulted in continental collision and ore deposit formation (from 12 to 6 Ma). This is represented by Cu-Au porphyry deposits in the New Guinea Orogen, and epithermal Au systems in the Papuan Peninsula. From 6 Ma, crustal delamination in Papua New Guinea, related to the prior Pocklington trough subduction resulted in adiabatic mantle melting with emplacement of diverse Cu and Au porphyry and epithermal deposits within the Papuan Fold and Thrust Belt and Papuan Peninsula from 6 Ma to the present day. Subduction at the New Britain and San Cristobal trenches from ca. 10 Ma resulted in an escalation in tectonic complexity and the onset of microplate tectonics in eastern Papua New Guinea and the Solomon Islands. This is reflected in the formation of diverse and discrete geodynamic settings for mineralization within the recent to modern arc setting, primarily related to upper plate shortening and extension and the spatial relationship to structures within the subducting slab.

Bowen, Alison, Orr, Ryan, McBeath, Anna V., Pattison, Anthony, and Nelson, Paul N. (2019) Suppressiveness or conduciveness to Fusarium wilt of bananas differs between key Australian soils. Soil Research, 57 (2). pp. 158-165.
Soils are known to differ in suppressiveness to soil-borne diseases, but the suppressiveness or otherwise to Fusarium wilt of Australian soils used to grow bananas is unknown. In this work we tested the relative suppressiveness of six key soil types. Banana (Musa (AAB group) 'Pome', cultivar 'Lady Finger') was grown in pots of the soils inoculated or not with Fusarium oxysporum f.sp. cubense (Foc) 'Race 1'. Sixteen weeks after inoculation the plants were harvested and disease severity was assessed by measuring discoloration within the rhizome. In the inoculated pots, disease severity was greatest in the alluvial Liverpool and Virgil soils and least in the basaltic origin Tolga soil. No disease was detected in the non-inoculated pots. Soils with the lowest disease severity had the highest root mass, irrespective of inoculation, and the largest (negative) effect of inoculation on root dry mass. Disease severity in inoculated pots was negatively correlated with soil clay content and β-glucosidase activity. The results indicate that the risk of Fusarium wilt negatively impacting banana growth differs between soils of the main Australian banana-growing region.

Mishra, A.K., Placzek, C., Wurster, C., and Whitehead, P.W. (2019) New radiocarbon age constraints for the 120 km-long Toomba flow, north Queensland, Australia. Australian Journal of Earth Sciences, 66 (1). pp. 71-79.
The Toomba flow is the youngest flow of the Nulla volcanic province, located in north Queensland. This 120 km-long flow has yielded a published 40Ar/39Ar age of 21,000 ± 3000 years. In contrast, seven published conventional radiocarbon (14C) analyses of carbon-bearing material beneath the flow yielded radiocarbon ages of 16,000 to <2500 BP. These radiocarbon ages are younger than the 40Ar/39Ar age, potentially due to contamination of the charcoal by younger carbon that was not removed by the acid–base pre-treatment. We have re-examined the radiocarbon age of Toomba flow using newly sampled charcoal buried beneath the Toomba flow in combination with hydrogen pyrolysis pre-treatment and accelerated mass spectrometer (AMS) measurements. We determined a calibrated radiocarbon age of 20,815–19,726 cal BP (2σ) for the material beneath the Toomba flow. Our radiocarbon age, therefore: (1) is older than previous radiocarbon ages for the Toomba flow, (2) provides the most precise age yet available for the Toomba flow, (3) is in agreement with the 40Ar/39Ar age, and (4) validates that hydrogen pyrolysis is a robust and effective pre-treatment method, for subtropical conditions where samples are susceptible to contamination by younger carbon. The Toomba flow erupted during the Last Glacial Maximum, but the preserved surface suggests that the rate of weathering and soil formation has been almost negligible in this region, despite being situated in a subtropical climate that experiences highly variable often intense rainfall.

Mishra, Ashish Kumar, Placzek, Christa, and Jones, Rhondda (2019) Coupled influence of precipitation and vegetation on millenial scale erosion rates derived from 10Be. PLoS ONE, 14 (1). e0211325.
Water is one of the main agent of erosion in many environmental settings, but erosion rates derived from beryllium-10 (10Be) suggests that a relationship between precipitation and erosion rate is statistically non-significant on a global scale. This might be because of the strong influence of other variables on erosion rate. In this global 10Be compilation, we examine if mean annual precipitation has a statistically significant secondary control on erosion rate. Our secondary variable assessment suggests a significant secondary influence of precipitation on erosion rate. This is the first time that the influence of precipitation on 10Be-derived erosion rate is recognized on global scale. In fact, in areas where slope is <200m/km (~11°), precipitation influences erosion rate as much as mean basin slope, which has been recognized as the most important variable in previous 10Be compilations. In areas where elevation is <1000m and slope is <11°, the correlation between precipitation and erosion rate improves considerably. These results also suggest that erosion rate responds to change in mean annual precipitation nonlinearly and in three regimes: 1) it increases with an increase in precipitation until ~1000 mm/yr; 2) erosion rate stabilizes at ~1000 mm/yr and decreases slightly with increased precipitation until ~2200 mm/yr; and 3) it increases again with further increases in precipitation. This complex relationship between erosion rate and mean annual precipitation is best explained by the interrelationship between mean annual precipitation and vegetation. Increased vegetation, particularly the presence of trees, is widely recognized to lower erosion rate. Our results suggest that tree cover of 40% or more reduces erosion rate enough to outweigh the direct erosive effects of increased rainfall. Thus, precipitation emerges as a stronger secondary control on erosion rate in hyper-arid areas, as well as in hyper-wet areas. In contrast, the regime between ~1000 and ~2200 mm/yr is dominated by opposing relationships where higher rainfall acts to increase erosion rate, but more water also increases vegetation/tree cover, which slows erosion. These results suggest that when interpreting the sedimentological record, high sediment fluxes are expected to occur when forests transition to grasslands/savannahs; however, aridification of grasslands or savannahs into deserts will result in lower sediment fluxes. This study also implies that anthropogenic deforestation, particularly in regions with high rainfall, can greatly increase erosion.

Duvert, Clément, Bossa, Mylène, Tyler, Kyle J., Wynn, Jonathan G., Munksgaard, Niels C., Bird, Michael I., Setterfield, Samantha A., and Hutley, Lindsay B. (2019) Groundwater‐derived DIC and carbonate buffering enhance fluvial CO2 evasion in two Australian tropical rivers. Journal of Geophysical Research: Biogeosciences, 124 (2). pp. 312-327.
Despite recent evidence suggesting that groundwater inputs of dissolved inorganic carbon (DIC) to rivers can contribute substantially to the fluvial evasion of carbon dioxide (CO2), groundwater is seldom integrated into fluvial carbon budgets. Also, unclear is the way equilibria between CO2 and ionic forms of carbonate will affect CO2 evasion from rivers. We conducted longitudinal river surveys of radon and carbon along two rivers of tropical Australia and developed a mass balance framework to assess the influence of groundwater‐derived inorganic carbon and carbonate buffering on CO2 evasion rates. The mean CO2 evasion flux totaled 8.5 and 2.3 g·C·m−2·day−1 for the two rivers, with considerable spatial variations that we attributed primarily to changes in groundwater inflow rates (minima and maxima per river reach 1.2–45.1 and 0.2–13.4 g·C·m−2·day−1). In the larger river system, inflowing groundwater delivered on average 6.7 g·C·m−2·day−1 as dissolved CO2—almost 10 times as much as the CO2 produced via river metabolism—and 21.6 g·C·m−2·day−1 as ionic forms. In both rivers, these groundwater‐derived inputs were a mixture of biogenic and geogenic carbon sources. Spatialized estimates of the carbonate buffering flux revealed that in reaches where CO2 evasion was particularly high, the carbonate system was able to maintain high CO2 concentrations by adjustment of carbonate equilibria. This process was likely triggered by high groundwater inflow rates. Our findings suggest that both groundwater inputs and carbonate equilibria need to be accounted for in fluvial carbon budgets, particularly in high‐alkalinity rivers.

Glasl, Bettina, Smith, Caitlin E., Bourne, David G., and Webster, Nicole S. (2019) Disentangling the effect of host-genotype and environment on the microbiome of the coral Acropora tenuis. PeerJ, 7. e6377.
Genotype-specific contributions to the environmental tolerance and disease susceptibility of corals are widely accepted. Yet our understanding of how host genotype influences the composition and stability of the coral microbiome subjected to environmental fluctuations is limited. To gain insight into the community dynamics and environmental stability of microbiomes associated with distinct coral genotypes, we assessed the microbial community associated with Acropora tenuis under single and cumulative pressure experiments. Experimental treatments comprised either a single pulse of reduced salinity (minimum of 28 psu) or exposure to the cumulative pressures of reduced salinity (minimum of 28 psu), elevated seawater temperature (+2°C), elevated pCO2(900 ppm), and the presence of macroalgae. Analysis of 16S rRNA gene amplicon sequence data revealed that A. tenuis microbiomes were highly host-genotype specific and maintained high compositional stability irrespective of experimental treatment. On average, 48% of the A. tenuis microbiome was dominated by Endozoicomonas. Amplicon sequence variants (ASVs) belonging to this genus were significantly different between host individuals. Although no signs of stress were evident in the coral holobiont and the vast majority of ASVs remained stable across treatments, a microbial indicator approach identified 26 ASVs belonging to Vibrionaceae, Rhodobacteraceae, Hahellaceae, Planctomycetes, Phylobacteriaceae, Flavobacteriaceae, and Cryomorphaceae that were significantly enriched in corals exposed to single and cumulative stressors. While several recent studies have highlighted the efficacy of microbial indicators as sensitive markers for environmental disturbance, the high host-genotype specificity of coral microbiomes may limit their utility and we therefore recommend meticulous control of host-genotype effects in coral microbiome research.

Diedrich, Amy, Blythe, Jessica, Petersen, Elizabeth, Euriga, Epsi, Fatchiya, Anna, Shimada, Takahiro, and Jones, Clive (2019) Socio-economic drivers of adoption of small-scale aquaculutre in Indonesia. Sustainability, 11 (6). 1543.

Rowe, Cassandra, David, Bruno, Mialanes, Jerome, Ulm, Sean, Petchey, Fiona, Aird, Samantha, McNiven, Ian J., Leavesley, Matthew, and Richards, Thomas (2019) A Holocene record of savanna vegetation dynamics in southern lowland Papua New Guinea. Vegetation History and Archaeobotany. (In Press)
The southern lowlands of Papua New Guinea (PNG) are biogeographically distinct. Vast tracts of savanna vegetation occur there and yet most palaeoecological studies have focused on highlands and/or forest environments. Greater focus on long-term lowland environments provides a rare opportunity to understand and promote the significance of local and regional savannas, ultimately allowing non-forested and forested ecosystem dynamics to be compared. This paper examines palaeoecological and archaeological data from a lowland open savanna site situated on the south-central PNG coastline. The methods used incorporate pollen and micro-charcoal analyses, artefact recovery and sediment descriptions. We conclude with an environmental model of sedimentation and vegetation change for the past c. 5,800 years, revealing a mid to late Holocene savanna interchange between herbaceous and woody plant growth, with fluctuating fire occurrence increasing toward the present day. Increased silt deposition and modified regional hydrology are also recorded. Environmental changes correspond in timing with the start of permanent settlements and human use of fire. In particular, landscape burning for hunting and gardens for agriculture have helped create the open ecosystem still evident today.

Bird, Michael, Cooper, Alan, Turney, Chris, Curnoe, Darren, Russell, Lynette, and Ulm, Sean (2019) Australia’s epic story: a tale of amazing people, amazing creatures and rising seas. The Conversation, 2019.
The Australian continent has a remarkable history — a story of isolation, desiccation and resilience on an ark at the edge of the world. It is a story of survival, ingenuity, and awe-inspiring achievements over many years.

Tavares, Silvia, and Dupré, Karine (2018) Cities can grow without wrecking reefs and oceans. Here's how. The Conversation, 11 December 2018.
[Extract] "What happens if the water temperature rises by a few degrees?" is the 2018 International Year of the Reef leading question. While the ocean is the focus, urbanisation is the main reason for the rising temperatures and water pollution. Yet it receives little attention in this discussion. In turn, rising temperatures increase downpours and urban floods, adding to the pressures on urban infrastructure.

Gurtner, Yetta (2018) Advancing the multi hazard early warning systems for emergency preparedness and disaster risk management. In: [Presented at the 12th APEC Senior Disaster Management Officials Forum]. From: 12th APEC Senior Disaster Management Officials Forum, 25-26 September 2018, Kokopo, Papua New Guinea.
Speech covering the concept and approaches to warning and data collection and analysis for warning, addressing the theme of the meeting touching in key questions to be addressed to improve warning.

Grimbacher, Peter S., Edwards, Will, Liddell, Michael J., Nelson, Paul N., Nichols, Cassandra, Wardhaugh, Carl W., and Stork, Nigel E. (2018) Temporal variation in abundance of leaf litter beetles and ants in an Australian lowland tropical rainforest is driven by climate and litter fall. Biodiversity and Conservation, 27 (10). pp. 2625-2640.
Determining if the seasonality of leaf litter invertebrate populations in tropical rainforests is driven by climate or availability of litter, or both, is important to more accurately predict the vulnerability of litter invertebrates to climate change. Here we used two approaches to disentangle these effects. First, the influence of climatic seasonality was quantified by sampling a fixed volume of litter monthly over 4 years and counting extracted beetles and ants. Second, litter volume was experimentally manipulated (addition and exclusion) to test the influence of litter quantity independently of climatic variation. There were significant seasonal peaks for both beetle and ant abundance and these were positively correlated with rainfall, temperature and litter volume. As abundance was measured on a 'per litter volume' basis we conclude that there was a significant effect of climate on abundance. The litter manipulation experiment showed that beetle and ant abundance per litter volume were also influenced by litter volume, when it was low. We recognise that other factors such as litter structure or complexity may have affected temporal ant abundance. Beetle and ant abundance were depressed in litter exclusion plots but did not differ significantly between control and addition plots, suggesting a possible ceiling in the effect of litter volume on population sizes. We conclude that seasonality in climate and litter quantity are driving most temporal variation in insect abundance and that there may be some resilience among leaf litter insects to cope with higher temperatures. However, future responses by plants to increased climatic variability and higher CO2 concentrations may alter litter fall dynamics and thus temporal patterns in litter insect abundances.

Bird, Michael I., Beaman, Robin J., Condie, Scott A., Cooper, Alan, Ulm, Sean, and Veth, Peter (2018) Palaeogeography and voyage modeling indicates early human colonization of Australia was likely from Timor-Roti. Quaternary Science Reviews, 191. pp. 431-439.
Anatomically Modern Humans (AMHs) dispersed rapidly through island southeast Asia (Sunda and Wallacea) and into Sahul (Australia, New Guinea and the Aru Islands), before 50,000 years ago. Multiple routes have been proposed for this dispersal and all involve at least one multi-day maritime voyage approaching 100 km. Here we use new regional-scale bathymetry data, palaeoenvironmental reconstruction, an assessment of vertical land movements and drift modeling to assess the potential for an initial entry into northwest Australia from southern Wallacea (Timor-Roti). From ∼70,000 until ∼10,000 years ago, a chain of habitable, resource-rich islands were emergent off the coast of northwest Australia (now mostly submerged). These were visible from high points close to the coast on Timor-Roti and as close as 87 km. Drift models suggest the probability of accidental arrival on these islands from Timor-Roti was low at any time. However, purposeful voyages in the summer monsoon season were very likely to be successful over 4–7 days. Genomic data suggests the colonizing population size was >72–100 individuals, thereby indicating deliberate colonization. This is arguably the most dramatic early demonstration of the advanced cognitive abilities and technological capabilities of AMHs, but one that could leave little material imprint in the archaeological record beyond the evidence that colonization occurred.

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