Tropical cyclones pose a significant threat to islanders in the tropical western Pacific. The extreme winds from these severe storms can cause extensive damage to housing, infrastructure and food production, whilst low lying areas can be adversely affected by storm surge inundation. As part of the Pacific Climate Change Science Program (PCCSP), Geoscience Australia is assessing the wind hazard posed by tropical cyclones for 14 islands in the western Pacific and Timor Leste. The assessment will cover both the current climate as well as projections for future climate scenarios. Wind hazard maps are being generated using Geoscience Australia's open-source Tropical Cyclone Risk Model (TCRM) that applies a statistical-parametric process to estimate return period wind speeds. The climate projections are produced by applying this model to downscaled storm tracks from global climate models. Two types of downscaled tracks are used for the projections: tracks of tropical-cyclone-like vortices directly detected in dynamically downscaled climate simulations and tracks derived from GCM's using a statistical/deterministic model (Emanuel 2006). The presentation will provide an outline of the method applied.

The cyclonic wind hazard over the Australian region is determined using synthetic tropical cyclone event sets derived from general circulation models (GCMs) to provide guidance on the potential impacts of climate change. Cyclonic wind hazard (defined as the return period wind speed) is influenced by the frequency, intensity and spatial distribution of tropical cyclones, all of which may change under future climate regimes due to influences such as warmer sea surface temperatures and changes in the global circulation. Cyclonic wind hazard is evaluated using a statistical-parametric model of tropical cyclones - the Tropical Cyclone Risk Model (TCRM) - which can be used to simulate many thousands of years of cyclone activity. TCRM is used to generate synthetic tracks which are statistically similar to the input event set - either an historical record or other synthetic event set. After applying a parametric wind field to the simulated tracks, we use the aggregated wind fields to evaluate the return period wind speeds for three IPCC AR4 scenarios, and make comparisons to the corresponding average recurrence interval wind speed estimates for current climate simulations. Results from the analysis of two GCMs are presented and contrasted with hazard estimates based on the historical record of tropical cyclones in the Australian region.

In recent years RIAG has developed a statistical model to assess severe wind hazard in the non-cyclonic regions of Australia ('Region A' as defined in the Australian/NZ Standards for Wind Loading of Structures (AS/NZS 1170.2, 2002)). The model has been tested using observational data from wind stations located in South Eastern Australia. The statistical model matched the results of the Australian/NZ standard for wind loading of structures utilising a more efficient, fully computational method (Sanabria & Cechet, 2007a). We present a methodology to assess severe wind hazard in Australia for regions where there are no observations. The methodology uses simulation data produced by a high resolution regional climate model in association with empirical gust factors. It compares wind speeds produced by the climate model with observations (mean wind speeds) and develops functions which allow wind engineers to correct the simulated data in order to match the observed mean wind speed data. The approach has been validated in a number of locations where observed records are available. In addition a Monte-Carlo modelling approach is utilised to relate extreme mean wind speeds to extreme peak gust wind speeds (Sanabria & Cechet, 2007b).

Climate change has become a real challenge for all nations throughout the world. The Fifth IPCC Assessment Report (2007) indicates that climate change is inevitable and those nations that quickly adapt will mitigate risk from the threats of the increased strength of tropical cyclones, storm surge inundation, floods and the spread of disease vectors. Decision making for adaptation will be more effective when it is based on evidence. Evidence-based disaster management means that decision makers are better informed, and the decision making process delivers more rational, representative and objective climate change outcomes. To achieve this, fundamental data needs to be translated into information and knowledge, before it can be put to use by the decision makers as policy, planning and implementation. The exposure to these increased natural hazards includes the communities, businesses, services, lifeline utilities and infrastructure. The thorough understanding of exposed infrastructure and population under current and future climate projections is fundamental to the process of future capacity building. The development of the National Exposure Information System (NEXIS) is a significant national project being undertaken by Geoscience Australia (GA). NEXIS collects, collates, manages and provides the information required to assess multi-hazard impacts. Exposure information is defined as a suite of elements at risk from climate change which includes human populations, buildings, businesses and infrastructure.

Coral reefs occur in shallow water with sea surface temperatures (SST) greater than 18ºC, extending beyond the tropics where warm currents enable their establishment [Hopley et al., 2007]. The southernmost reef in the Pacific Ocean occurs at Lord Howe Island (31° 30°S), fringing 6 km of the western margin of the island, with isolated reef patches on the north, west and eastern sides. The island is a Miocene volcanic remnant on the western flank of the Lord Howe Rise (foundered continental crust) formed of basaltic cliffs rising to 875 m, flanked by Quaternary eolianites [McDougall et al., 1981]. The reefs support 50-60 species of scleractinian corals, whose rates of growth are only slightly slower than in more tropical locations [Harriott and Banks, 2002]. However, carbonate sediments on the surrounding shelf are dominated by temperate biota, such as foraminifera and algal rhodoliths [Kennedy et al., 2002]. Prominent in mid shelf is a broad ridge-like feature that rises from water depths of 30-50 m, which we considered to be a relict coral reef that formerly encircled the island [Woodroffe et al., 2005, 2006]. This paper describes results of sonar swath mapping to determine the extent of the reef, and coring and dating that establishes its age and demise.

The degree to which palaeoclimatic changes in the Southern Hemisphere co-varied with events in the high latitude Northern Hemisphere during the Last Termination is a contentious issue, with conflicting evidence for the degree of `teleconnection' between different regions of the Southern Hemisphere. The available hypotheses are difficult to test robustly, however, because there are few detailed palaeoclimatic records in the Southern Hemisphere. Here we present climatic reconstructions from the southwestern Pacific, a key region in the Southern Hemisphere because of the potentially important role it plays in global climate change. The reconstructions for the period 20-10 kyr BP were obtained from five sites along a transect from southern New Zealand, through Australia to Indonesia, supported by 125 calibrated 14C ages. Two periods of significant climatic change can be identified across the region at around 17 and 14.2 cal kyr BP, most probably associated with the onset of warming in the West Pacific Warm Pool and the collapse of Antarctic ice during Meltwater Pulse-1A, respectively. The severe geochronological constraints that inherently afflict age models based on radiocarbon dating and the lack of quantified climatic parameters make more detailed interpretations problematic, however. There is an urgent need to address the geochronological limitations, and to develop more precise and quantified estimates of the pronounced climate variations that clearly affected this region during the Last Termination.

Climate change is a challenge facing nations worldwide. The Fifth IPCC Assessment Report (2007) indicated that climate change is inevitable and that nations need to quickly adapt to mitigate its effects on the risks associated with increased tropical cyclone intensity, storm surge inundation, floods and exacerbated spread of disease. Nationally consistent exposure information is required to understand the risks associated with climate change and thereby support decision making on adaptation options. Decision makers can draw on this evidence-base to develop more rational, representative and objective strategies for addressing emerging challenges. Exposure information requires the translation of fundamental data into information and knowledge before it can be put to use for policy, planning and implementation. Communities, businesses, essential services and infrastructure are all exposed to these increased natural hazards. A thorough understanding of exposed infrastructure, building stock and population under current and future climate projections is fundamental to the process of future capacity building. The National Exposure Information System (NEXIS) provides a broad range of information on the exposure profile of any given area at various administrative and disaster sensitive geographic resolutions with Australia-wide coverage. The information is collected, collated and maintained at building level that can subsequently be aggregated geographically. The information recorded in NEXIS covers a wide range of building attributes such as building type, construction type and year built together with information on population demographics and metrics on business activity such as business type, turnover, employee numbers and customer capacity.

The Garnaut Climate Change Review is an independent study by Professor Ross Garnaut, commissioned by Australia's State and Territory Governments. The Review is examining the impacts of climate change on the Australian economy, in an effort to recommend medium to long-term policies and policy frameworks to improve the prospects for sustainable prosperity. Geoscience Australia's (GA) outputs for the Garnaut Review consider the economic impacts of tropical cyclones on Queensland, the Northern Territory and Western Australia (severe wind and storm surge impacts) for eight climate change greenhouse gas emission scenarios based on model projections of large-scale environmental factors from the Intergovernmental Panel for Climate Change (IPCC) Fourth Assessment Report simulations. The study focuses on the evaluation of the wind hazard utilising the maximum potential intensity (MPI). This sets a thermodynamic, theoretical upper limit for the distribution of TC intensities obtained by a TC given a vertical temperature and humidity profile and given location. Storm surge impacts in the same States are developed using a simple parameterisation relating changes in TC intensity to changes in storm surge height including the adoption of the IPCC global mid-point sea-level rise predictions. For this study we consider 20 year time slices centred on; 2010, 2030, 2050, 2070, and 2090. For each time-slice and for each region, we produce the spatial return-period 'tropical cyclone wind gust speed' ranging from return-periods of 50 years to 5000 years. Direct losses (infrastructure damage) are calculated for each return-period event. The combined losses (severe wind and storm surge) were regressed to obtain a Probable Maximum Loss (PML) curve for each study region. The average annual cost to the region due to exposure to tropical cyclones across a 5000 year period or Annualised losses are evaluated for each study region. Expressing the annualised loss as a percentage of total reconstruction gives a measure of the intensity of the risk to the studied community that is not so evident in simple dollar values. State annualised loss estimates of direct loss were aggregated from estimates at the SLA (statistical local area) level. The aim of the Garnaut Review is to compare the 'business as usual' scenario (A1FI) with a range of stabilisation scenarios.

Cyclone Tracy is the only tropical cyclone to have devastated a major Australian population centre. When most adult Australians picture devastation to buildings and infrastructure caused by a cyclone, it is the images of Darwin in the aftermath of Cyclone Tracy that most readily comes to mind. Following the disaster (December 1974), the Australian Government implemented significantly improved building standards aim at reducing the impact of a similar event in future. Here we utilise impact modelling, where we separately assess hazard, exposure and vulnerability for both 1974 and present-day to evaluate the resulting effectiveness of the improved building codes. As often occurs in extreme natural disasters, meteorological instrumentation failed prior to the maximum wind gusts being recorded, so the spatial extent of the peak wind gusts were inferred from models constrained by estimates of the observed maximum peak wind gust. Geoscience Australia has develop models of severe wind risk, covering the Australian continent. One component of this is the tropical cyclone risk model (TCRM), which estimates the winds and impacts associated with tropical cyclones. In this study, we utilise the vulnerability relationships determined in recent years for similar circa 1974 structures and our knowledge of the type and specific location of structures at the time, to make the link between hazard and impact/damage. This spatial damage estimation (site specific values) is compared with the observed (post-event survey) damage in an effort to validate the model.

The development of climate change adaptation policies must be underpinned by a sound understanding of climate change risk. As part of the Hyogo Framework for Action, governments have agreed to incorporate climate change adaptation into the risk reduction process. This paper explores the nature of climate change risk assessment in the context of human assets and the built environment. More specifically, the paper's focus is on the role of spatial data which is fundamental to the analysis. The fundamental link in all of these examples is the National Exposure Information System (NEXIS) which has been developed as a national database of Australia's built infrastructure and associated demographic information. The first illustrations of the use of NEXIS are through post-disaster impact assessments of a recent flood and bushfire. While these specific events can not be said to be the result of climate change, flood and bushfire risks will certainly increase if rainfall or drought become more prevalent, as most climate change models indicate. The second example is from Australia's National Coastal Vulnerability Assessment which is addressing the impact of sea-level rise and increased storms on coastal communities on a national scale. This study required access to or the development of several other spatial databases covering coastal landforms, digital elevation models and tidal/storm surge. Together, these examples serve to illustrate the importance of spatial data to the assessment of climate change risk and, ultimately, to making informed, cost-effective decisions to adapt to climate change.