SEVERE STORMS ON THE EAST COAST OF AUSTRALIA 1770 – 2008 Jeff Callaghan Research Fellow, Griffith Centre for Coastal Management, Griffith University, Gold Coast, Qld Formerly Head Severe Storm Forecaster, Bureau of Meteorology, Brisbane Dr Peter Helman Senior Research Fellow, Griffith Centre for Coastal Management, Griffith University, Gold Coast, Qld Published by Griffith Centre for Coastal Management, Griffith University, Gold Coast, Queensland 10 November 2008 This publication is copyright. Apart from any fair dealing for the purpose of private study, research, criticism or review, as permitted under the Copyright Act, no part may be reproduced by any process without written permission from the publisher. ISBN: 978-1-921291-50-0 Foreword Severe storms can cause dramatic changes to the coast and devastation to our settlements. If we look back through history, to the first European observations by James Cook and Joseph Banks on Endeavour in 1770, we can improve our understanding of the nature of storms and indeed climate on the east coast. In times of climate change, it is essential that we understand natural climate variability that occurs in Australia. Looking back as far as we can is essential to understand how climate is likely to behave in the future. Studying coastal climate through this chronology is one element of the process. Analysis of the records has already given an indication that east coast climate fluctuates between phases of storminess and drought that can last for decades. Although records are fragmentary and not suitable for statistical analysis, patterns and climate theory can be derived. The dependence on shipping for transport and goods since European settlement ensures a good source of information on storms that gradually improves over time. The Bathurst Bay Hurricane stands out in history as the most severe storm experienced on this coast. It occurred in March 1899, so it can only be estimated as a category 5 tropical cyclone by the complete devastation it caused; over 350 people were killed and 100 vessels destroyed. A century later with extensive developments along much of the coast, a category 5 tropical cyclone would have enormous impacts. In the last 30 years, even allowing for TC Larry (2000), there have been a relatively low number of storms. We need to be prepared for severe storms that will undoubtedly occur in the future. Given the compelling evidence for climate change, and the research which indicates that storms may increase in intensity, our coastal communities need to understand the extent of their vulnerability to these events. This publication provides a timely reminder of the power of nature and impact of coastal storms on the natural and built environment. Professor Rodger Tomlinson BE PhD FIEAust CPEng Director Griffith Centre for Coastal Management And Griffith Climate Response Program Callaghan and Helman GCCM, Griffith University front page 1 INTRODUCTION This chronology was developed to study the relationship between severe storms and coastline change on the east coast of Australia. It dates back to the first known European observations made by James Cook in 1770. Coastal droughts and floods are included, making it representative of two centuries of east coast climate variability. Understanding climate variability is essential when considering the future impacts of climate change. On the coast, climate change is represented as a slowly accelerating sea level rise, only expressed when severe storms provide energy for erosion and inland coastal movement. Climate change may also increase the frequency, intensity and southward extent of severe tropical storms. Coastal developments already at risk may be subjected to further pressures. Two centuries of documented variability demonstrates how climate extremes, such as severe storm periods and drought, occur in alternate phases that can last for decades. For example, the storms, floods and erosion from the 1950’s to 1970’s compared to the last three decades of recurring droughts. These phases have been related to oscillations of the Pacific Ocean described by the Interdecadal Pacific Oscillation (IPO) index (Helman 2007). Much of the chronology covers periods before reliable observations began, making this compilation unsuitable for statistical analysis. Information Sources The chronology includes significant weather events, calms, storms, droughts, floods and observations on coastal features such as: river bars, marine deltas, beaches, dunes and erosion. Major volcanic eruptions and tsunami’s are also included. It does not include thunderstorm cells, which can cause local damage. Records are considered for the east coast of Australia from Cape York to Tasmania. Contemporary names, from current maps and charts, have been used for the location of events. The geographic divisions of the east coast referred to in the chronology are shown in Figure A. A wide range of published and compiled records are referenced. Many types of records were reviewed as evidence of significant events prior to the preparation of daily weather maps around 1880. The maritime records are not a ‘shipwreck’ record but are used to determine storm occurrence. While there is general agreement between authorities, some early records demonstrate significant disagreements due to inadequate or conflicting primary sources. Such records have been treated cautiously. Minor discrepancies between historical authorities have been ignored. Significant differences are noted after the citation. Callaghan and Helman GCCM, Griffith University front page 2 Figure A: Descriptive divisions of the east coast, Australia. The east coast is divided into 8 sections: Queensland – FNQ (far north), NQ (north), CQ (central), SEQ (south east) coasts. New South Wales – N (north), M (mid north), C (central) and S (south) coasts, divisions previously used by PWD 1985. Callaghan and Helman GCCM, Griffith University front page 3 RECORD CATEGORIES 1770 to 1788 Records are limited and a summary of events from available sources is included. 1788 to 1820 Prior to exploration and establishment of Port Macquarie and Moreton Bay penal colonies, most records are from the early colonial settlement and shipping activities around Sydney. Records from limited voyages in the Coral and Tasman Seas, including some New Zealand records have been considered. 1820 to 1880 During this period there was increased settlement and shipping, especially the cedar trade along the New South Wales and southern Queensland coasts. Details are compiled from: historical accounts in maritime records, local coastal histories and records compiled by the Bureau of Meteorology. 1881 to 2008 For NSW coast, storm events from 1881–1985 are classified by PWD 1985 and PWD 1986. For south east Queensland and severe storms to the north (Coral Sea), information was sourced from Beach Protection Agency (BPA) 1985, 1989, Bureau of Meteorology (BoM) and records of severe storms compiled by Jeff Callaghan. Comparison of records 1881–1919 For the period 1881 to 1919, historical storm records are compared to the published NSW coast storm record (PWD 1985). Observations from BoM website From the early 1900’s, consistent observations made by the Bureau of Meteorology and newspaper accounts cover many severe storms. EAST COAST STORMS Severe storms can occur at any time of year but are more likely to occur between December and July. The Australian east coast is not only influenced by immediate storms but also from swells that originate thousands of kilometres away in the Pacific Ocean. East coast storms are typically tropical storms in the Coral Sea between November and April. Extra tropical storms in the Tasman Sea, and temperate storms in the Southern Ocean, can occur at any time of year but tend to occur from January to August. Storm Names Tropical cyclones were first named in 1894 by Clement Wragge in Queensland, the practise was discontinued but was recommenced by Bureau of Meteorology in 1963. In historic literature many storms are named in memory of the loss of a ship, its crew and passengers, for example the Maitland Gale 1889 and the Cawarra Storm 1866. Other storms are referred to by two names, for example the most severe storm recorded on the east coast, in far north Queensland, 1899, is referred to as the Bathurst Bay Hurricane or the Mahina Cyclone, named and located by Clement Wragge in a weather map. Due to delays in receiving information, the map was not published until the storm had made landfall (Townsend 2008). Some of the more notable storms are named after significant Callaghan and Helman GCCM, Griffith University front page 4 shipping losses, such as the Volunteer Storm 1864, after an early shipwreck at Cape Byron. STORM INTENSITY Classification of severe storms depends on the criteria used: tropical cyclone categories, central pressure, wind strength, wind damage, storm surge, number killed or injured, flood height and recently insurance claims. Storm intensity prior to 1881 is assessed from historical records and is only indicative, after 1881 it follows PWD 1985, PWD 1986 and BoM cyclone classification. The table below compares the different classifications used. In the chronology, the shaded rows are used to show the classified ‘severe storms’. SEVERE STORMS Only one cyclone Cat 5 (estimated) has been recorded on the east coast in the last 200 years, the Bathurst Bay Hurricane (4–5 March 1899), this storm also claims the lowest central pressure (914hPa), the highest storm surge (14.6m), the highest number of casualties