187 research outputs found

    Adaptation of Australia's marine ecosystems to climate change: using science to inform conservation management

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    The challenges that climate change poses for marine ecosystems are already manifesting in impacts at the species, population, and community levels in Australia, particularly in Tasmania and tropical northern Australia. Many species and habitats are already under threat as a result of human activities, and the additional pressure from climate change significantly increases the challenge for marine conservation and management. Climate change impacts are expected to magnify as sea surface temperatures, ocean chemistry, ocean circulation, sea level, rainfall, and storm patterns continue to change this century. In particular, keystone species that form the foundation of marine habitats, such as coral reefs, kelp beds, and temperate rocky reefs, are projected to pass thresholds with subsequent implications for communities and ecosystems. This review synthesises recent science in this field: the observed impacts and responses of marine ecosystems to climate change, ecological thresholds of change, and strategies for marine conservation to promote adaptation. Increasing observations of climate-related impacts on Australia’s marine ecosystems—both temperate and tropical—are making adaptive management more important than ever before. Our increased understanding of the impacts and responses of marine ecosystems to climate change provides a focus for "no-regrets" adaptations that can be implemented now and refined as knowledge improve

    Tropical cyclone contribution to extreme rainfall over southwest Pacific Island nations

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    Southwest Pacific nations are among some of the worst impacted and most vulnerable globally in terms of tropical cyclone (TC)-induced flooding and accompanying risks. This study objectively quantifies the fractional contribution of TCs to extreme rainfall (hereafter, TC contributions) in the context of climate variability and change. We show that TC contributions to extreme rainfall are substantially enhanced during active phases of the Madden–Julian Oscillation and by El Niño conditions (particularly over the eastern southwest Pacific region); this enhancement is primarily attributed to increased TC activity during these event periods. There are also indications of increasing intensities of TC-induced extreme rainfall events over the past few decades. A key part of this work involves development of sophisticated Bayesian regression models for individual island nations in order to better understand the synergistic relationships between TC-induced extreme rainfall and combinations of various climatic drivers that modulate the relationship. Such models are found to be very useful for not only assessing probabilities of TC- and non-TC induced extreme rainfall events but also evaluating probabilities of extreme rainfall for cases with different underlying climatic conditions. For example, TC-induced extreme rainfall probability over Samoa can vary from ~ 95 to ~ 75% during a La Niña period, if it coincides with an active or inactive phase of the MJO, and can be reduced to ~ 30% during a combination of El Niño period and inactive phase of the MJO. Several other such cases have been assessed for different island nations, providing information that have potentially important implications for planning and preparing for TC risks in vulnerable Pacific Island nations. © 2021, The Author(s). *Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “Anil Deo and Savin Chand” is provided in this record*

    Facilitating student understanding about climate science: El Niño as an online case study

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    El Niño – Southern Oscillation (ENSO) has been shown to be the dominant factor affecting year-to-year climate changes globally, and may dramatically affect rainfall patterns around the world. In the education of climate scientists, it is critical that they comprehend the complex concepts that underpin ENSO. This paper discusses an online practical (tool) developed to teach undergraduate students the fundamental principles that underpin not only the average state of the ocean, but also ocean variability associated with ENSO. Results from two formal student evaluations of this practical, one by third year physical geography students and the other by second year physics students, will be presented and discussed

    Climate drivers of the 2015 Gulf of Carpentaria mangrove dieback

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    ESCC Hub researchers investigated the oceanic and atmospheric conditions leading up to the major mangrove dieback in late 2015 to identify potential stressors that contributed to the tree deaths. They found that it was most likely a result of a combination of very dry conditions and lower than average sea level. In combination, it appears that these conditions were unprecedented since at least 1971, and linked to the strong El Niño of 2015/16. More detailed attribution studies are necessary to determine what role, if any, human-induced climate change played in the 2015 dieback event. This would help inform natural resource policy-makers, planners and associated decision-makers about the causes of such events and how they may change into the future

    Categorizing and naming marine heatwaves

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    Considerable attention has been directed at understanding the conse-quences and impacts of long-term anthropogenic climate change. Discrete, climati-cally extreme events such as cyclones, floods, and heatwaves can also significantly affect regional environments and species, including humans. Climate change is expected to intensify these events and thus exacerbate their effects. Climatic extremes also occur in the ocean, and recent decades have seen many high-impact marine heatwaves (MHWs)—anomalously warm water events that may last many months and extend over thousands of square kilometers. A range of biological, economic, and political impacts have been associated with the more intense MHWs, and measuring the sever-ity of these phenomena is becoming more important. Progress in understanding and public awareness will be facilitated by consistent description of these events. Here, we propose a detailed categorization scheme for MHWs that builds on a recently published classification, combining elements from schemes that describe atmospheric heatwaves and hurricanes. Category I, II, III, and IV MHWs are defined based on the degree to which temperatures exceed the local climatology and illustrated for 10 MHWs. While there is a long-term increase in the occurrence frequency of all MHW categories, the largest trend is a 24% increase in the area of the ocean where strong (Category II) MHWs occur. Use of this scheme can help explain why biological impacts associated with different MHWs can vary widely and provides a consistent way to compare events. We also propose a simple naming convention based on geography and year that would further enhance scientific and public awareness of these marine events

    Global Water Governance and Climate Change: Identifying Innovative Arrangements for Adaptive Transformation

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    A convoluted network of different water governance systems exists around the world. Collectively, these systems provide insight into how to build sustainable regimes of water use and management. We argue that the challenge is not tomake the systemless convoluted, but rather to support positive and promising trends in governance, creating a vision for future environmental outcomes. In this paper, we analyse nine water case studies from around the world to help identify potential ‘innovative arrangements’ for addressing existing dilemmas. We argue that such arrangements can be used as a catalyst for crafting new global water governance futures. The nine case studies were selected for their diversity in terms of location, scale and water dilemma, and through an examination of their contexts, structures and processes we identify key themes to consider in the milieu of adaptive transformation. These themes include the importance of acknowledging socio-ecological entanglements, understanding the political dimensions of environmental dilemmas, the recognition of different constructions of the dillema, and the importance of democratized processes.The research for this paper is a part of the “CADWAGO: Climate change adaptation and water governance—reconciling food security, renewable energy and the provision of multiple ecosystem services” project funded as part of the “Europe and Global Challenges programme” by Compagnia di San Paolo, VolkswagenStiftung and Riksbankens Jubileumsfond.https://www.mdpi.com/2073-4441/10/1/2

    Very high resolution mapping of coral reef state using airborne bathymetric LiDAR surface-intensity and drone imagery

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    International audienceVery high resolution (VHR) airborne data enable detection and physical measurements of individual coral reef colonies. The bathymetric LiDAR system, as an active remote sensing technique, accurately computes the coral reef ecosystem’s surface and reflectance using a single green wavelength at the decimetre scale over 1-to-100 km2 areas. A passive multispectral camera mounted on an airborne drone can build a blue-green-red (BGR) orthorectified mosaic at the centimetre scale over 0.01-to-0.1 km2 areas. A combination of these technologies is used for the first time here to map coral reef ecological state at the submeter scale. Airborne drone BGR values (0.03 m pixel size) serve to calibrate airborne bathymetric LiDAR surface and intensity data (0.5 m pixel size). A classification of five ecological states is then mapped through an artificial neural network (ANN). The classification was developed over a small area (0.01 km2) in the lagoon of Moorea Island (French Polynesia) at VHR (0.5 m pixel size) and then extended to the whole lagoon (46.83 km2). The ANN was first calibrated with 275 samples to determine the class of coral state through LiDAR-based predictors; then, the classification was validated through 135 samples, reaching a satisfactory performance (overall accuracy = 0.75)

    A stakeholder-guided marine heatwave hazard index for fisheries and aquaculture

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    Marine heatwaves pose an increasing threat to fisheries and aquaculture around the world under climate change. However, the threat has not been estimated for the coming decades in a form that meets the needs of these industries. Tasmanian fisheries and aquaculture in southeast Australia have been severely impacted by marine heatwaves in recent years, especially the oyster, abalone, and salmon industries. In a series of semi-structured interviews with key Tasmanian fishery and aquaculture stakeholders, information was gathered about the following: (i) the impacts they have experienced to date from marine heatwaves, (ii) their planning for future marine heatwaves, and (iii) the information that would be most useful to aid planning. Using CMIP6 historical and future simulations of sea surface temperatures around Tasmania, we developed a marine heatwave hazard index guided by these stakeholder conversations. The region experienced a severe marine heatwave during the austral summer of 2015/16, which has been used here as a reference point to define the index. Our marine heatwave hazard index shows that conditions like those experienced in 2015/16 are projected to occur approximately 1-in-5 years by the 2050s under a low emissions scenario (SSP1-2.6) or 1-in-2 years under a high emissions scenario (SSP5-8.5). Increased frequency of marine heatwaves will likely reduce productivity by both direct (mortality) and in-direct (ecosystem change, greater incidence of disease) impacts on target species. The illustrative hazard index is one step towards a marine heatwave risk index, which would also need to consider aspects of exposure and vulnerability to be of greater utility to stakeholders
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