Dr Danielle Verdon-Kidd

© 2017 Elsevier B.V. The Monsoonal North West (MNW) region of Australia faces a number of challenges adapting to anthropogenic climate change. These have the potential to impact on a range of industries, including agricultural, pastoral, mining and tourism. However future changes to rainfall regimes remain uncertain due to the inability of Global Climate Models to adequately capture the tropical weather/climate processes that are known to be important for this region. Compounding this is the brevity of the instrumental rainfall record for the MNW, which is unlikely to represent the full range of climatic variability. One avenue for addressing this issue (the focus of this paper) is to identify sources of paleoclimate information that can be used to reconstruct a plausible pre-instrumental rainfall history for the MNW. Adopting this approach we find that, even in the absence of local sources of paleoclimate data at a suitable temporal resolution, remote paleoclimate records can resolve 25% of the annual variability observed in the instrumental rainfall record. Importantly, the 507-year rainfall reconstruction developed using the remote proxies displays longer and more intense wet and dry periods than observed during the most recent ~ 100 years. For example, the maximum number of consecutive years of below (above) average rainfall is 90% (40%) higher in the rainfall reconstruction than during the instrumental period. Further, implications for flood and drought risk are studied via a simple GR1A rainfall runoff model, which again highlights the likelihood of extremes greater than that observed in the limited instrumental record, consistent with previous paleoclimate studies elsewhere in Australia. Importantly, this research can assist in informing climate related risks to infrastructure, agriculture and mining, and the method can readily be applied to other regions in the MNW and beyond.

© 2016 Author(s). Recent efforts to understand tropical cyclone (TC) activity in the southwest Pacific (SWP) have led to the development of numerous TC databases. The methods used to compile each database vary and are based on data from different meteorological centres, standalone TC databases and archived synoptic charts. Therefore the aims of this study are to (i) provide a spatiooral comparison of three TC best-track (BT) databases and explore any differences between them (and any associated implications) and (ii) investigate whether there are any spatial, temporal or statistical differences between pre-satellite (1945-1969), postsatellite (1970-2011) and post-geostationary satellite (1982-2011) era TC data given the changing observational technologies with time. To achieve this, we compare three besttrack TC databases for the SWP region (0-35° S, 135° E-120° W) from 1945 to 2011: the Joint TyphoonWarning Center (JTWC), the International Best Track Archive for Climate Stewardship (IBTrACS) and the Southwest Pacific Enhanced Archive of Tropical Cyclones (SPEArTC). The results of this study suggest that SPEArTC is the most complete repository of TCs for the SWP region. In particular, we show that the SPEArTC database includes a number of additional TCs, not included in either the JTWC or IBTrACS database. These SPEArTC events do occur under environmental conditions conducive to tropical cyclogenesis (TC genesis), including anomalously negative 700 hPa vorticity (VORT), anomalously negative vertical shear of zonal winds (VSZW), anomalously negative 700 hPa geopotential height (GPH), cyclonic (absolute) 700 hPa winds and low values of absolute vertical wind shear (EVWS). Further, while changes in observational technologies from 1945 have undoubtedly improved our ability to detect and monitor TCs, we show that the number of TCs detected prior to the satellite era (1945-1969) are not statistically different to those in the postsatellite era (post-1970). Although data from pre-satellite and pre-geostationary satellite periods are currently inadequate for investigating TC intensity, this study suggests that SPEArTC data (from 1945) may be used to investigate longterm variability of TC counts and TC genesis locations.

© 2016 Author(s). The destruction caused by tropical cyclone (TC) Pam in March 2015 is considered one of the worst natural disasters in the history of Vanuatu. It has highlighted the need for a better understanding of TC impacts and adaptation in the Southwest Pacific (SWP) region. Therefore, the key aims of this study are to (i) understand local perceptions of TC activity, (ii) investigate impacts of TC activity and (iii) uncover adaptation strategies used to offset the impacts of TCs. To address these aims, a survey (with 130 participants from urban areas) was conducted across three SWP small island states (SISs): Fiji, Vanuatu and Tonga (FVT). It was found that respondents generally had a high level of risk perception and awareness of TCs and the associated physical impacts, but lacked an understanding of the underlying weather conditions. Responses highlighted that current methods of adaptation generally occur at the local level, immediately prior to a TC event (preparation of property, gathering of food, finding a safe place to shelter). However higher level adaptation measures (such as the modification to building structures) may reduce vulnerability further. Finally, we discuss the potential of utilising weather-related traditional knowledge and non-traditional knowledge of empirical and climate-model-based weather forecasts to improve TC outlooks, which would ultimately reduce vulnerability and increase adaptive capacity. Importantly, lessons learned from this study may result in the modification and/or development of existing adaptation strategies.

© 2015 Author(s). Rainfall intensity-frequency-duration (IFD) relationships are commonly required for the design and planning of water supply and management systems around the world. Currently, IFD information is based on the "stationary climate assumption" that weather at any point in time will vary randomly and that the underlying climate statistics (including both averages and extremes) will remain constant irrespective of the period of record. However, the validity of this assumption has been questioned over the last 15 years, particularly in Australia, following an improved understanding of the significant impact of climate variability and change occurring on interannual to multidecadal timescales. This paper provides evidence of regime shifts in annual maximum rainfall time series (between 1913-2010) using 96 daily rainfall stations and 66 sub-daily rainfall stations across Australia. Furthermore, the effect of these regime shifts on the resulting IFD estimates are explored for three long-term (1913-2010) sub-daily rainfall records (Brisbane, Sydney, and Melbourne) utilizing insights into multidecadal climate variability. It is demonstrated that IFD relationships may under-or over-estimate the design rainfall depending on the length and time period spanned by the rainfall data used to develop the IFD information. It is recommended that regime shifts in annual maximum rainfall be explicitly considered and appropriately treated in the ongoing revisions of the Engineers Australia guide to estimating and utilizing IFD information, Australian Rainfall and Runoff (ARR), and that clear guidance needs to be provided on how to deal with the issue of regime shifts in extreme events (irrespective of whether this is due to natural or anthropogenic climate change). The findings of our study also have important implications for other regions of the world that exhibit considerable hydroclimatic variability and where IFD information is based on relatively short data sets.

© Inter-Research 2014. There is a recognised gap between what climate science can currently provide and what end users of that information require to make robust adaptation decisions about their climate-related risks. This issue has been identified as a major barrier to successful climate change adaptation outcomes and is emphasised within the water resource management and agricultural sectors because of high uncertainty surrounding precipitation projections. This paper details the outcomes of a survey and workshop aimed at better understanding this gap. To bridge the gap, it is recommended that communication and packaging of climate information be improved via a formalised 'knowledge broker'. It is also suggested that a 'terms of reference' for key climate change-related terms be developed and agreed upon by both climate science providers and end users to reduce the misuse of terminology and subsequent confusion. Further, it is recommended that additional research be conducted into natural variability and baseline risk to provide a realistic background on which climate change projections and associated uncertainties are assessed. Finally, for successful climate change adaptation, new tools and methods are needed that deal explicitly with end user needs and the practical limitations end users face (e.g. time, funding, human resources, politics) when attempting to make robust decisions under climate change-related uncertainty.

A shift in climate occurred during the mid-1970s that affected the hydroclimate of the Southern Hemisphere resulting in drying trends across continental regions including Australia, New Zealand and southern and western Africa. There is also anecdotal evidence of other periods of climatic synchronicity in the Southern Hemisphere (e.g., the 1920s and 1940s), indicating that the mid-1970s event may not be anomalous. This paper identifies periods within the last ~120 years using statistical analysis where dry spells (in terms of annual to multi-decadal rainfall deficiencies) have coincided across the continental Southern Hemisphere in order to characterize temporal consistency. It is shown that synchronicity of dry spells is (a) most likely common over the last 120 years and (b) associated with changes in the large-scale climate modes of the Pacific, Indian and Southern Oceans. Importantly, the findings presented in this paper have marked implications for drought management and drought forecasting studies in the Southern Hemisphere. © Author(s) 2014.

Southeast Australia (SEA) experienced a protracted drought during the mid-1990s until early 2010 (known as the Big Dry or Millennium Drought) that resulted in serious environmental, social and economic effects. This paper analyses a range of historical climate data sets to place the recent drought into context in terms of Southern Hemisphere inter-annual to multi-decadal hydroclimatic variability. The findings indicate that the recent Big Dry in SEA is in fact linked to the widespread Southern Hemisphere climate shift towards drier conditions that began in the mid-1970s. However, it is shown that this link is masked because the large-scale climate drivers responsible for drying in other regions of the mid-latitudes since the mid-1970s did not have the same effect on SEA during the mid-to late 1980s and early 1990s. More specifically, smaller-scale synoptic processes resulted in elevated autumn and winter rainfall (a crucial period for SEA hydrology) during the mid-to late 1980s and early 1990s, which punctuated the longer-term drying. From the mid-1990s to 2010 the frequency of the synoptic processes associated with elevated autumn/winter rainfall decreased, resulting in a return to drier than average conditions and the onset of the Big Dry. The findings presented in this paper have marked implications for water management and climate attribution studies in SEA, in particular for understanding and dealing with "baseline" (i.e. current) hydroclimatic risks. © 2014 Author(s).

© 2015, Engineers Australia. All rights reserved. Worldwide, severe droughts have extensive environmental impacts, such as declined crop yield and livestock production, inadequate water supply and elevated risk of bushfires. Additionally, dealing with drought breaking floods adds significant strain to society and the economy, particularly when businesses and communities are not prepared. Increasing vulnerability to droughts with reduced per capita water storage, particularly in semiarid regions such as the Murray Darling Basin (MDB), Australia, underscores the need for predictive understanding of drought. However, at present, useful forecasts of persistent drought or drought breaking conditions are not yet achievable due to our incomplete understanding of the controls on drought extent and duration. Therefore, to better coordinate drought planning and drought relief activities, it is imperative to understand the factors affecting drought initialisation and cessation. In this paper, the spatial and temporal characteristics of historical droughts (both meteorological and hydrological) that have affected in the MDB are examined. It is shown that historically, drought has varied spatially across the MDB, with significant differences (in terms of timing and severity of drought) between the Upper and Lower MDB. It is also shown that meteorological droughts tend to develop gradually over the MDB, while hydrological drought develops much more rapidly. Further, it is shown that climate drivers of Pacific origin (i.e. El Nino/Southern Oscillation and Interdecadal Pacific Oscillation) play a significant role in drought initiation for the majority of historical droughts since 1900 and, for northern MDB droughts, anomalously cool SSTs off the Northwest of Australia precede all but one of the historical droughts identified. Undoubtedly the reoccurrence of drought places a major strain on the agricultural and water resource management sectors and imposes major economic and social losses. However, with improved knowledge of the climate mechanisms controlling the onset of drought periods, alleviation of the effects may be achieved through improved forecasts and management practices designed specifically to deal with such events.