Climate Change and Coastal Flooding
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COUNTING THE COSTS: CLIMATE CHANGE AND COASTAL FLOODING The Climate Council is an independent, crowd-funded organisation providing quality information on climate change to the Australian public. CLIMatECOUNCIL.ORG.AU Authorship: Will Steffen, John Hunter and Lesley Hughes Published by the Climate Council of Australia Limited ISBN: 978-0-9941623-0-4 (print) 978-0-9941623-1-1(web) © Climate Council of Australia Ltd 2014 This work is copyright the Climate Council of Australia Ltd. All material contained in this work is copyright the Climate Council of Australia Ltd except where a third party source is indicated. Climate Council of Australia Ltd copyright material is licensed under the Creative Commons Attribution 3.0 Australia License. To view a copy of this license visit http://creativecommons.org.au You are free to copy, communicate and adapt the Climate Council of Australia Ltd copyright material so long as you attribute the Climate Council of Australia Ltd and the authors in the following manner: Counting the Costs: Climate Change and Coastal Flooding by Will Steffen, John Hunter and Lesley Hughes (Climate Council of Australia). Permission to use third party copyright content in this publication can be sought from the relevant third party copyright owner/s. This report is printed on 100% recycled paper. Preface This is the 14th publication of the Climate We are extremely grateful to our team Council. The Climate Council is an of reviewers whose comments and independent, non-profit organisation, suggestions improved the report. funded by donations from the public. The reviewers were: Jon Barnett Our mission is to provide authoritative, (University of Melbourne), Melanie expert information to the Australian Bishop (Macquarie University), Bruce public on climate change. Thom (University of Sydney) and Stefan Trueck (Macquarie University). Many Australians live on or near the We thank CSIRO for reviewing the coast. The major population centres accuracy and relevance of the science —Sydney, Melbourne, Brisbane, Perth, underpinning the report. Their review is Adelaide, Hobart and Darwin—are all not an endorsement of the conclusions port cities and much of the nation’s drawn. We are also grateful to our expert critical infrastructure—transport, contributors—Frank Jotzo (Australian commercial, residential, defence—is National University) and Jan McDonald located along our coastlines. Virtually (University of Tasmania)—for their all of this infrastructure has been case studies (boxes) in this report. designed and built for a stable climate We thank the Climate Council staff with known ranges of variability. But for their many contributions to the the climate system is no longer stable. production of this report. Sea level is rising and so are the risks for our coastal infrastructure. The authors retain sole responsibility for the content of the report. This report explores two of the most serious consequences of rising sea level—the large increase in the frequency of coastal inundation and the recession of ‘soft’ shorelines. Damage caused by increased coastal Professor Will Steffen inundation and recession poses a Climate Councillor massive financial burden due to damage and destruction of infrastructure. Coastal inundation and recession also have important implications for health and well-being, coastal ecosystems and communities. The report describes how Dr John Hunter scientific understanding of sea-level rise has improved significantly over the last decade, and we also explore the challenge of making better decisions Professor Lesley Hughes about future coastal development. Climate Councillor Finally, the report discusses the urgent need to stabilise the climate to reduce the level of risks from coastal flooding in the future. CLIMATECOUNCIL.ORG.AU Page i COUNTING THE COSTS: CLIMATE CHANGE AND COASTAL FLOODING Introduction A ustralia is largely a coastal country. rates of sea-level rise, as well as a better Much of our population lives on or near understanding of regional variations the coast, and our six state capital cities around the Australian coast. We can —Sydney, Melbourne, Brisbane, Perth, assess the relative importance of various Adelaide and Hobart, as well as Darwin factors, such as the warming of ocean in the Northern Territory—are all water and the loss of ice from the polar port cities. In addition to the many ice sheets, in driving sea-level rise. lifestyle amenities from living on the Our knowledge of the behaviour of the coast, much of the nation’s critical large polar ice sheets, such as those in infrastructure—transport, commercial, Greenland and West Antarctica, has also residential, defence—is located along improved, allowing better assessments our coastlines. Virtually all of this of the risks from rapid and/or irreversible infrastructure has been designed and loss of ice from these regions. built for a stable climate with known Infrastructure that we are designing ranges of variability. But the climate and building now should take climate system is no longer stable. Sea levels change into account, but this is often are rising and so are the risks they not the case. In addition to a solid pose for our coastal infrastructure. scientific knowledge base, perceptions, The most immediate and serious values, institutions, rules and other consequence of rising sea level is social factors are crucially important the flooding of coastal areas through in developing appropriate responses to both inundation and recession (see climate-related risks. An acceptance of Section 1). Coastal flooding creates the reality of climate change and its risks many risks, including impacts on health is essential, but much more is needed. and well-being, damage to coastal The challenge is to build effective ecosystems and disruption of people’s approaches for dealing with the risks lives. In addition to these, the risks to to existing infrastructure as well as coastal infrastructure – the major focus making better decisions about future of this report - are potentially huge, infrastructure development. particularly the economic losses due to Ultimately, stabilising the climate is damage and destruction and the flow-on necessary to reduce the level of risks effects to the economy more generally. from coastal flooding.R apid and deep Scientific understanding of sea-level rise cuts in greenhouse gas emissions are has improved significantly over the last critical here in Australia and around decade. We now have more reliable and the world to stabilise the climate. accurate information on the observed Page ii CLIMATECOUNCIL.ORG.AU Contents Preface i Introduction ii Key findings iv 1. Sea-level rise, coastal flooding and coastal infrastructure .........................1 2. The science of sea-level rise .........................................................................................................7 2.1 Observations of sea-level rise 8 2.2 Projections of future sea-level rise 12 2.3 Increased probability of coastal flooding 16 2.4 Other contributing factors to risks of sea-level rise 20 3. Counting the costs ................................................................................................................................21 3.1 Infrastructure exposed to coastal flooding 23 3.2 Observed economic costs of coastal flooding 25 3.3 Projected costs of coastal flooding in future 28 3.4 Other impacts of coastal flooding 34 4. How can we deal with the risks? ............................................................................................44 4.1 The nature of the challenge 45 4.2 Do nothing: The head-in-the-sand approach 48 4.3 Stabilise the climate system: Reducing greenhouse gas emissions 51 4.4 Be prepared: Adapting to the sea-level rise we can’t avoid 53 5. The bottom line .........................................................................................................................................58 References 60 CLIMATECOUNCIL.ORG.AU Page iii COUNTING THE COSTS: CLIMATE CHANGE AND COASTAL FLOODING Key findings 1. Sea level has already risen a business-as-usual approach to and continues to rise due burning fossil fuels would drive to climate change. Climate it towards the upper end. change exacerbates coastal › A sea-level rise of only 0.5 m flooding from a storm surge would, on average, mean that as the storm rides on higher a 1-in-a-100 year flood—a very sea levels. rare event today—would occur › Climate change drives up sea every few months. It could also level by warming the oceans and involve a potential retreat of sandy increasing the flow of ice from the shorelines by 25 to 50 m. land into the sea, for instance from › Sydney is particularly vulnerable. melting glaciers. It is likely that today’s 1-in-100 year › Over half the Australian coastline is flood would occur every day or so vulnerable to recession from rising by 2100. sea level, with 80% of the Victorian 3. Coastal flooding is a sleeping coast and 62% of the Queensland giant. If the threat of sea level coast at risk. rise is ignored, the projected › At both Fremantle and Sydney, increases in economic flooding events became three times damage caused by coastal more frequent during the 20th flooding are massive. century as a result of sea-level rise. › More than $226 billion in › With just 10 cm of sea level rise commercial, industrial, road and the risks of coastal flooding rail, and residential assets around roughly treble. Australian coasts are potentially 2. Australia is highly vulnerable exposed to flooding and erosion to increasing