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The tropics are expanding poleward at an alarming rate-with massive implications for societies, economies, and natural environments. This expansion appears to be determined largely by anthropogenic drivers-notably rises in greenhouse gases. Of greatest concern is the poleward shift of the dry sub-tropical zone into highly populated regions that have generally enjoyed a more temperate climate. While the effects of latitudinal shifts of climate zones will be most severe in temperate regions outside the tropics, there will also be significant changes in climate within the tropics-notably unprecedented thermal conditions for hundreds of millions of people, along with projections for more extreme weather events. Australia's geographical location makes it particularly vulnerable to an expanding tropics. As the tropics expand poleward, more of southern Australia will be influenced by the dry sub-tropical zone and associated reductions in winter rainfall. These drying trends are projected to continue over most southern parts of Australia this century, accompanied by rising temperatures and more hot days. Future rainfall trends for northern Australia remain uncertain, but there is an expected significant increase in the number of hot days, together with more extreme weather events. Future climate change in northern Australia has been ignored by the White Paper for the Development of Northern Australia (2015), bringing into serious question the feasibility and affordability of many of the development policies, plans, and projects promulgated in the White Paper. Even without climate change, the north faces many significant environmental and economic challenges for its future development. [ABSTRACT FROM AUTHOR]

Pride in Australia's extreme climate has long been a part of Australia's national identity. Today, climate continues to be enrolled in a range of nationalistic projects, including the (re)development of climate science and other responses to climate change. In this paper, we outline some of the contours of the 'Australian national climate', claims to know it, and four idealised responses to it: bounce back, dismissal, endurance, and migration. We argue that the deeply cultural framing of climate in Australia-in particular, Australians' emphasis on the climate's inherent variability and unknowability, and their own historical adaptability-is being exploited by the federal government and hampering climate change mitigation nationally. [ABSTRACT FROM AUTHOR]

Bushfires are one of the most frequent natural hazards experienced in Australia. Fires play an important role in shaping the landscape and its ecological dynamics, but may also have devastating effects that cause human injuries and fatalities, as well as broad-scale environmental damage. While there has been considerable effort to quantify changes in the occurrence of bushfire in Australia, a comprehensive assessment of the most extreme bushfire cases, which exact the greatest economic and environmental impacts, is lacking. In this paper we reflect upon recently developed understanding of bushfire dynamics to consider (i) historical changes in the occurrence of extreme bushfires, and (ii) the potential for increasing frequency in the future under climate change projections. The science of extreme bushfires is still a developing area, thus our conclusions about emerging patterns in their occurrence should be considered tentative. Nonetheless, historical information on noteworthy bushfire events suggests an increased occurrence in recent decades. Based on our best current understanding of how extreme bushfires develop, there is strong potential for them to increase in frequency in the future. As such there is a pressing need for a greater understanding of these powerful and often destructive phenomena. [ABSTRACT FROM AUTHOR]

The impacts on the Australian coast of a changing climate include environmental and property damage arising from increased frequency and severity of coastal weather events, storm surge, coastal erosion, and coastal flooding. Coastal management policies and planning laws are often relied upon to manage both the impacts and competing interests in the coast. The existence of these policies and laws, and their interpretation by the courts, bears a weight of expectation upon them to deliver in the face of climate change which merits further consideration. Indeed, a rich field is open from which to consider the constitution and construction of law in and across different places, in the context of climate change adaptation. The Australian coast is a unique and locally specific context from which to explore the relationship between law and place as performed in the Vaughan litigation, and this paper considers such important potential as it gains expression in the Vaughan litigation. © 2016 Institute of Australian Geographers [ABSTRACT FROM AUTHOR]

High‐resolution climate change projections are increasingly necessary to inform climate policy and adaptation planning. Downscaling of global climate models (GCMs) is required to simulate the climate at the spatial scale relevant for local impacts. Here, we dynamically downscaled 15 CMIP6 GCMs to a 10 km resolution over Australia using the Conformal Cubic Atmospheric model (CCAM), creating the largest ensemble of high‐resolution downscaled CMIP6 projections for Australia. We compared the host CMIP6 models and downscaled simulations to the Australian Gridded Climate Data (AGCD) observational data and evaluated performance using the Kling‐Gupta efficiency and Perkins skill score. Downscaling improved performance over host GCMs for seasonal temperature and precipitation (10% and 43% respectively), and for annual cycles of temperature and precipitation (6% and 13% respectively). Downscaling also improved the fraction of dry days, reducing the bias for too many low‐rain days. The largest improvements were found in climate extremes, with enhancements to extreme minimum temperatures in all seasons varying from 142% to 201%, and to extreme precipitation of 52% in Austral winter and 47% in summer. The ensemble average integrated skill score improved by 16%. Temperature and precipitation biases were reduced in mountainous and coastal areas. CCAM downscaling outperformed host CMIP6 GCMs at multiple spatial scales and regions—continental Australia, Australian IPCC regions and Queensland's regions—with integrated added value ranging from 9% to 150% and higher over densely populated regions more exposed to climate impacts. This data set will be a valuable resource for understanding future climate changes in Australia. Plain Language Summary: High‐resolution climate models are used for producing climate change projections for assessing regional and local climate change impacts and for adaptation and policy formulation. We completed 15 high‐resolution climate simulations using the Conformal Cubic Atmospheric Model at a 10 km spatial resolution over the Australian continent and surrounds based on global climate models (GCMs) used in the Intergovernmental Panel on Climate Change Assessment Report 6. We evaluated the new high‐resolution data set by comparing it to observations and to their host global model across several regions within Australia. The high‐resolution simulations improved the representation of topography, seasonal temperature and annual cycles of temperature, precipitation, as well as the number of dry days, extreme precipitation and extreme minimum temperatures. The high‐resolution projections show improvement compared to GCMs consistently across spatial scales and regions, being particularly high (150%) over urban areas with high exposure to impacts. This new 10 km data set is the highest resolution, and largest ensemble of the latest climate projections for the Australian continent and surrounds and will be a valuable tool for evaluating future climate change impacts. Key Points: We dynamically downscaled 15 CMIP6 global climate model simulations over Australia to a 10 km spatial resolution using the Conformal Cubic Atmospheric modelTwo new assessment metrics are proposed to assess model performance and added value of downscalingThe integrated added value of downscaling can be as high as 150% over highly populated areas [ABSTRACT FROM AUTHOR]

Systematic changes, since the beginning of the 20th century, in average and extreme Australian rainfall and temperatures indicate that Southern Australian climate has undergone regime transitions into a drier and warmer state. South-west Western Australia (SWWA) experienced the most dramatic drying trend with average streamflow into Perth dams, in the last decade, just 20% of that before the 1960s and extreme, decile 10, rainfall reduced to near zero. In south-eastern Australia (SEA) systematic decreases in average and extreme cool season rainfall became evident in the late 1990s with a halving of the area experiencing average decile 10 rainfall in the early 21st century compared with that for the 20th century. The shift in annual surface temperatures over SWWA and SEA, and indeed for Australia as a whole, has occurred primarily over the last 20 years with the percentage area experiencing extreme maximum temperatures in decile 10 increasing to an average of more than 45% since the start of the 21st century compared with less than 3% for the 20th century mean. Average maximum temperatures have also increased by circa 1 °C for SWWA and SEA over the last 20 years. The climate changes in rainfall an d temperatures are associated with atmospheric circulation shifts. [ABSTRACT FROM AUTHOR]

The Pliocene was characterized by a gradual shift of global climate toward cooler and drier conditions. This shift fundamentally reorganized Earth's climate from the Miocene state toward conditions similar to the present. During the Pliocene, the progressive restriction of the Indonesian Throughflow (ITF) is suggested to have enhanced this shift toward stronger meridional thermal gradients. Reduced ITF, caused by the northward movement of Australia and uplift of Indonesia, impeded global thermohaline circulation, also contributing to late Pliocene Northern Hemisphere cooling via atmospheric and oceanographic teleconnections. Here we present an orbitally tuned high‐resolution sediment geochemistry, calcareous nannofossil, and X‐ray fluorescence record between 3.65 and 2.97 Ma from the northwest shelf of Australia within the Leeuwin Current. International Ocean Discovery Program Site U1463 provides a record of local surface water conditions and Australian climate in relation to changing ITF connectivity. Modern analogue‐based interpretations of nannofossil assemblages indicate that ITF configuration culminated ~3.54 Ma. A decrease in warm, oligotrophic taxa such as Umbilicosphaera sibogae, with a shift from Gephyrocapsa sp. to Reticulofenestra sp., and an increase of mesotrophic taxa (e.g., Umbilicosphaera jafari and Helicosphaera spp.) suggest that tropical Pacific ITF sources were replaced by cooler, fresher, northern Pacific waters. This initial tectonic reorganization enhanced the Indian Oceans sensitivity to orbitally forced cooling in the southern high latitudes culminating in the M2 glacial event (~3.3 Ma). After 3.3 Ma the restructured ITF established the boundary conditions for the inception of the Sahul‐Indian Ocean Bjerknes mechanism and increased the response to glacio‐eustatic variability. Key Points: The Indonesian Throughflow connection between the equatorial Pacific and the Indian Ocean was tectonically restricted by 3.54 MaOrbitally tuned Pliocene multiproxy record links paleoenvironmental conditions on the Australian northwest shelf with global climateLate Pliocene glacio‐eustatic changes established the Sahul‐Indian Ocean Bjerknes mechanism and enhanced seasonality in Australia [ABSTRACT FROM AUTHOR]

In this study we evaluate the ability of an ensemble of high-resolution Regional Climate Model simulations to represent snow cover characteristics over the Australian Alps and go on to asses future projections of snowpack characteristics. Our results show that the ensemble presents a cold temperature bias and overestimates total precipitation leading to a general overestimation of the snow cover as compared with MODIS satellite data. We then produce a new set of snowpack characteristics by running a temperature based snow melt/accumulation model forced by bias corrected temperature and precipitation fields. While some positive snow cover biases remain, the bias corrected (BC) dataset show large improvements regarding the simulation of total amounts, seasonality and spatial distribution of the snow cover compared with MODIS products. Both the raw and BC datasets are then used to assess future changes in the snowpack characteristics. Both datasets show robust increases in near-surface temperatures and decreases in snowfall that lead to a substantial reduction of the snowpack over the Australian Alps. The snowpack decreases by about 15 and 60% by 2030 and 2070 respectively. While the BC data introduce large differences in the simulation of the present climate snowpack, in relative terms future changes appear to be similar to those obtained using the raw data. Future temperature projections show a clear dependence with elevation through the snow-albedo feedback effect that affects snowpack projections. Uncertainties in future projections of the snowpack are large in both datasets and are mainly dominated by the choice of the lateral boundary conditions. [ABSTRACT FROM AUTHOR]

Within the context of climate change, it is of utmost importance to quantify the stability of ecosystems with respect to climate anomalies. It is well acknowledged that ecosystem stability may change over time. As these temporal stability changes may provide a warning for increased vulnerability of the system, this study provides a methodology to quantify and assess these temporal changes in vegetation stability. Within this framework, vegetation stability changes were quantified over Australia from 1982 to 2006 using GIMMS NDVI and climate time series (i.e., SPEI (Standardized Precipitation and Evaporation Index)). Starting from a stability assessment on the complete time series, we aim to assess: (i) the magnitude and direction of stability changes; and (ii) the similarity in these changes for different stability metrics, i.e., the standard deviation of the NDVI anomaly (SD), auto-correlation at lag one of the NDVI anomaly (AC) and the correlation of NDVI anomaly with SPEI (CS). Results show high variability in magnitude and direction for the different stability metrics. Large areas and types of Australian vegetation showed an increase in variability (SD) over time; however, vegetation memory (AC) decreased. The association of NDVI anomalies with drought events (CS) showed a mixed response: the association increased in the western part, while it decreased in the eastern part. This methodology shows the potential for quantifying vegetation responses to major climate shifts and land use change, but results could be enhanced with higher resolution time series data. [ABSTRACT FROM AUTHOR]

There are gaps in the existing climate change adaptation literature concerning the design of spatial planning instruments and the relationship between policy instruments and the sociopolitical barriers to adaptation reform. To help address this gap, this article presents a typology of spatial planning instruments for adaptation and analyses the pattern of instrument choice in Australian planning processes in order to shed light on contextual factors that can impede adaptation. The analysis highlights how policy design can amplify the barriers to adaptation by arranging policy actors in ways inimical to reform and stripping decision makers of the instruments necessary to make and sustain desired policy changes. [ABSTRACT FROM PUBLISHER]

Australia has been exposed to a vast array of extreme weather regimes over the past few years, and the frequency and intensity of these events are expected to increase as a result of anthropogenic climate change. However, the predictability of extreme droughts, heat waves (HWs), bushfires and floods, is still hampered by our inability to fully understand how these weather systems interact with each other and with the climate system. This study brings new insight into the regional and large scale dynamics of some extreme events in Australia, by describing and comparing the climate signature of summer HWs and extreme rainfall events which have occurred in the states of Victoria and Queensland respectively, during 1979-2013. Our analyses highlight the importance of mid-latitude dynamics operating during HWs, in contrast with more tropical interactions at play during extreme rainfall events. A 'common' blocking high pressure system is observed over the Tasman Sea during the two types of extreme events, and may explain why some southeastern HWs (only about 25 %) occur in close succession with floods in Queensland. However, our results suggest that there is no dynamical link between these two types of events, since the HW-related anticyclone evolves as part of a baroclinic wave train, whereas in the case of rainfall events, this structure emerges as an equivalent barotropic response to tropical convection. Sub-regional surface temperatures and air-sea fluxes also suggest that distinct processes may be operating in the lead up to these two events. Indeed, HWs tend to occur when the wave train propagates from the south Indian to the Pacific Ocean, inducing a quasi-stationary blocking high system over the Tasman Sea. This anticyclonic anomaly can then advect hot dry air towards the southern Victorian coast, where it produces HW conditions. On the other hand, extreme rainfall events mostly occur when the background conditions correspond to a La Niña state. The convection induced in the western Pacific can trigger a tropical-extratropical teleconnection over Queensland. This may generate an anticyclonic anomaly over the Tasman Sea, able to divert air parcels over a warm and humid area where conditions are, this time, favorable for more extreme rainfall along the Queensland coast. [ABSTRACT FROM AUTHOR]

The International Ocean Discovery Program (IODP) Expedition 356 Site U1461 cored a Miocene to Holocene sedimentary sequence in the upper bathyal carbonate offshore northwestern Australia (NWA). The siliciclastic component of these strata is primarily derived from the Australian continent. Radiocarbon dating on macrofossils and planktonic foraminifera shows that the upper 14 m section at Site U1461 preserves Holocene sediments, recording regional climate variability. K/Ca ratios determined by X-ray fluorescence elemental analyses and %K determined by shipboard natural gamma ray analysis are interpreted as indicators of riverine run-off from the Australian continent. We document the consequences of the variability of the Australian Summer Monsoon (ASM) on the continental shelf of NWA. We report an increase in terrigenous input due to a riverine run-off after 11.5 ka, which reaches a maximum at ~ 8.5 ka. This maximum is the result of the enhanced ASM-derived precipitation in response to the southern migration of the Intertropical Convergence Zone (ITCZ). A decrease in riverine run-off due to a weakening of precipitation in the NWA region after 8.5 ka was caused by the northern migration of the ITCZ. We conclude that the ITCZ reached its southernmost position at 8.5 ka and enhanced precipitation in the NWA region. This Holocene record shows that even during interglacial periods, monsoonal variability was primarily controlled by the position of the ITCZ. [ABSTRACT FROM AUTHOR]