tag:theconversation.com,2011:/id/topics/coastal-defences-10395/articlesCoastal defences – The Conversation2022-11-30T00:40:01Ztag:theconversation.com,2011:article/1953572022-11-30T00:40:01Z2022-11-30T00:40:01ZCoastal property prices and climate risks are both soaring. We must pull our heads out of the sand<p>Australians’ <a href="https://www.nfsa.gov.au/collection/curated/australians-beach">well-documented</a> affinity with the sun, surf and sand continues to fuel <a href="https://www.smh.com.au/property/news/stunning-holiday-hotspots-where-house-prices-have-doubled-in-five-years-20221109-p5bwuk.html">coastal property market growth</a>. This growth defies rising interest rates and growing evidence of the <a href="https://www.theguardian.com/australia-news/2020/jul/23/against-the-tide-storm-battered-wamberal-residents-cling-to-beachfront-homes">impacts of climate change</a> on people living in vulnerable coastal locations. </p>
<p>People in these areas are finding it harder to insure their properties against these risks. Insurers view the Australian market as sensitive to climate risks, as climate change impacts can trigger large insurance payouts. They are <a href="https://www.theguardian.com/australia-news/2022/nov/12/australians-facing-prohibitive-insurance-premiums-after-climate-related-disasters">pricing their products accordingly</a>. </p>
<p>Clearly, there is a vast disconnect between the coastal property market and climate change impacts such as increasingly severe storms, tidal surges, coastal erosion and flooding. There is no shortage of <a href="https://www.smh.com.au/business/banking-and-finance/32-billion-of-cba-mortgages-exposed-to-extreme-weather-risks-climate-analysis-finds-20220819-p5bb5p.html">reports</a>, <a href="https://www.climatecouncil.org.au/resources/australian-homes-uninsurable-2030-climate-risk-map/">studies</a> and <a href="https://www.abc.net.au/news/2022-11-18/gold-coast-council-additional-88-000-properties-at-flood-risk/101664596">analyses</a> confirming the climate risks we are already living with. Yet another alarming <a href="https://www.csiro.au/en/research/environmental-impacts/climate-change/State-of-the-Climate">State of the Climate</a> report was released last week.</p>
<p>We keep talking about reaching global net-zero emissions. But this “<a href="https://www.youtube.com/watch?v=ZwD1kG4PI0w">blah blah blah</a>” masks the fact that climate impacts are already with us. Even if we make deeper, faster cuts to emissions, as we must, our world is now warmer. Australians will <a href="https://www.science.org.au/supporting-science/science-policy-and-analysis/reports-and-publications/risks-australia-three-degrees-c-warmer-world">feel the effects of that warming</a>. </p>
<p>We ultimately cannot afford the price of business as usual, as embodied by so many coastal developments. </p>
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<figcaption><span class="caption">Greta Thunberg denounces the ‘blah, blah, blah’ from world leaders in response to the climate emergency.</span></figcaption>
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Read more:
<a href="https://theconversation.com/state-of-the-climate-what-australians-need-to-know-about-major-new-report-195136">State of the climate: what Australians need to know about major new report</a>
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<h2>Risks are worrying banks and insurers</h2>
<p>In Australia, the disasters and the environmental collapse we are experiencing will get worse. While a range of businesses see this as opening up <a href="https://www.accc.gov.au/media-release/accc-internet-sweeps-target-greenwashing-fake-online-reviews">new market and product frontiers</a>, the fact is climate change is creating a fundamentally uncertain, unstable and difficult world. </p>
<p>Banks have a <a href="https://law-store.wolterskluwer.com/s/product/banking-on-climate-change-how-finance-actors-regulatory-regimes/01t0f00000J3aMk">central role</a> in addressing climate risks. They are <a href="https://theconversation.com/how-can-your-bank-help-reduce-climate-change-risks-to-your-home-60049">exposed to climate risk</a> through residential lending on properties that are vulnerable to climate impacts and now <a href="https://www.theguardian.com/australia-news/2022/nov/26/australias-unraveling-climate-risk-leaving-more-homes-uninsurable-against-flooding-expert-warns">face insurance pressures</a>. </p>
<p>One in 25 Australian homes are <a href="https://www.climatecouncil.org.au/resources/australian-homes-uninsurable-2030-climate-risk-map/">projected to be uninsurable by 2030</a>. The Australian government risks bearing the large costs of supporting the underinsured or uninsured – otherwise known as <a href="https://www.pc.gov.au/inquiries/completed/disaster-funding/report">being “the insurer of last resort”</a>.</p>
<p>This costly legacy shows why planning decisions made now must take account of climate change impacts, and <a href="https://link.springer.com/article/10.1007/s40641-020-00161-z">not just in the wake of disasters</a>.</p>
<p>The rapidly escalating impacts and risks across sectors demand that we undertake mitigation and adaptation at the same time, urgently and on a large scale. This means reducing emissions to negative levels – not just reaching net zero and transitioning our energy sector, but also actively removing greenhouse gases from the atmosphere. </p>
<p>We must also respond to climate change risks already locked into the system. We have to make substantial changes in how we think about, treat, price and act on these risks. </p>
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<a href="https://theconversation.com/how-insurers-can-get-better-at-responding-to-natural-disasters-75846">How insurers can get better at responding to natural disasters</a>
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<h2>As the climate shifts, so must our coastal dream</h2>
<p>The consequences of a warming climate, including reaching and crossing tipping points in the Earth’s weather systems, are <a href="https://www.science.org/doi/10.1126/science.abn7950#core-collateral-purchase-access">occurring sooner than anticipated</a>. The required behavioural, institutional and structural changes are vast and challenging. </p>
<p>People are often attached to places based on <a href="https://rgs-ibg.onlinelibrary.wiley.com/doi/abs/10.1111/tran.12368">historical knowledge</a> of them. These lived experiences, while important, inform a worldview based on an understanding of our environment before the <a href="https://link.springer.com/chapter/10.1007/978-981-19-2428-6_2">rapid onset</a> of climate change. This can skew our climate risk responses, but compounding climate impacts are outpacing our ability to adapt as we might have in the past. </p>
<p>Institutional signalling, such as <a href="https://www.smh.com.au/business/the-economy/property-values-are-at-risk-in-climate-change-hot-spots-rba-warns-20210917-p58skt.html">warnings by the Reserve Bank</a>, support greater public awareness of climate impacts and risks. </p>
<p>When buying a property, people need to consider these factors more seriously than, say, having an extra bathroom. Obligatory disclosure of regional climate change impacts could inform buyers’ decision-making. The data and models used would have to be clear on the validity and limitations of their scenarios. </p>
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Read more:
<a href="https://theconversation.com/building-too-close-to-the-water-its-ridiculous-talk-of-buyouts-after-floods-shows-need-to-get-serious-about-climate-adaptation-186999">'Building too close to the water. It's ridiculous!' Talk of buyouts after floods shows need to get serious about climate adaptation</a>
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<h2>Nature-based and equitable solutions</h2>
<p>In recent years there has been an increasing focus on nature-based solutions. This approach uses natural systems and tools for tackling societal issues such as the enormous and complex risks posed by climate change. Indeed, many Indigenous peoples, communities and ways of knowing <a href="https://www.facetsjournal.com/doi/full/10.1139/facets-2019-0058">have long recognised</a> the fundamental role of nature in making good and safe lives possible for people. </p>
<p>Nature-based solutions provide a suite of valuable tools for remedying issues we’re already facing on coasts. <a href="https://www.sciencedirect.com/science/article/abs/pii/S0964569121000399">For example</a>, in many contexts, building hard seawalls is often a temporary solution, which instils a false sense of security. Planting soft barriers such as mangroves and dense, deep-rooting vegetation can provide a more enduring solution. It also restores fish habitat, purifies water and eases floods.</p>
<p>Acknowledging the well-being of people and nature as interconnected has important implications for decisions about relocating people from high-risk areas. Effective planned retreat strategies must not only get people out of harm’s way, but account for where they will move and how precious ecosystems will be protected as demand for land supply shifts. Nature-based solutions must be built into retreat policies too. </p>
<p>As the Australian Academy of Science’s <a href="https://www.science.org.au/news-and-events/events/launch-national-strategy-just-adaptation">Strategy for Just Adaptation</a> explains, effective adaptation also embeds equity and justice in the process. <a href="https://link.springer.com/article/10.1007/s10584-019-02535-1">Research</a> on historic retreat strategies has shown that a failure to properly consider and respect people’s choices, resources and histories can further entrench inequities. Giving people moving to a new home as much choice as possible helps them work through an emotional and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0964569116301119">highly political process</a>.</p>
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<a href="https://theconversation.com/after-the-floods-the-distressing-but-necessary-case-for-managed-retreat-178641">After the floods, the distressing but necessary case for managed retreat</a>
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<p>We all need to find the courage to have difficult conversations, to seek information to make prudent choices, and to do all we can to respond to the growing climate risks that confront us. As climate activist Greta Thunburg <a href="https://www.youtube.com/watch?v=ZwD1kG4PI0w">says</a>: </p>
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<p>“Hope is not passive. Hope is not blah blah blah. Hope is telling the truth. Hope is taking action. And hope always comes from the people.” </p>
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<p>Acting on this kind of hope can put us on an altogether different and more positive path.</p><img src="https://counter.theconversation.com/content/195357/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tayanah O'Donnell has previously received research funding from AMP Foundation, the BHP Foundation, the Lord Mayor's Charitable Trust, the Institute of Australian Geographers, Western Sydney University, the University of Canberra, and state and federal governments. These grants supported over 13 years of research in climate change adaptation and in sustainable development, including managed retreat, climate policy, and climate risk duties and disclosures. She is a Deloitte Australia Climate and Sustainability Partner where she leads the Canberra climate practice. She is also an honorary Associate Professor at the Australian National University. </span></em></p><p class="fine-print"><em><span>Eleanor Robson is a PhD student at Western Sydney University and a Manager in Deloitte's Risk Advisory practice. Eleanor has formerly worked for a parliamentarian in the Australian Labor Party. </span></em></p>Booming prices for coastal properties are a mark of our reluctance to reckon with the climate change that is already upon us. We must start to properly account for and act on climate risk.Tayanah O'Donnell, Honorary Associate Professor, Australian National UniversityEleanor Robson, PhD Candidate, Institute for Culture and Society, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1790442022-03-22T13:26:23Z2022-03-22T13:26:23ZConcrete fuels climate change – but there’s a nature-friendly way to defend coasts from rising seas<figure><img src="https://images.theconversation.com/files/453590/original/file-20220322-28-vmqrzd.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3427%2C2692&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/concrete-breakwaters-seascape-tetrapodes-protect-coastal-1042670491">Maksym Medvinskyi/Shutterstock</a></span></figcaption></figure><p>The Tōhoku earthquake of 2011 remains the <a href="https://www.nationalgeographic.org/thisday/mar11/tohoku-earthquake-and-tsunami/">strongest</a> in recorded Japanese history. It created a tsunami that towered <a href="https://www.bbc.co.uk/bitesize/guides/zg9h2nb/revision/6#:%7E:text=On%2011%20March%202011%2C%20a,heights%20of%20over%2040%20metres">over 40 metres</a> and <a href="https://link.springer.com/article/10.1007/s11069-013-0567-4">dismantled coastal flood defences</a> in north-eastern Japan with ease, taking the lives of around 16,000 people.</p>
<p>Japanese authorities, wanting to better protect communities in future, chose to build bigger defences. Concrete walls that span 400km and reach nearly <a href="https://www.theb1m.com/video/japans-400-kilometre-tsunami-shield">15 metres high</a> in places now line the coast to resist incoming waves and allow enough time for residents to evacuate in the event of another tsunami. </p>
<p>They were recently tested by a 7.4 magnitude earthquake, which struck off the coast of the Fukushima prefecture on March 16 2022, <a href="https://edition.cnn.com/2022/03/16/asia/japan-earthquake-fukushima-intl/index.html">killing at least four people</a> and injuring many more. Mercifully, the resulting tsunami was negligible compared with that of 11 years prior.</p>
<p>These sea walls will also serve as a defensive frontline against the effects of climate change. <a href="https://www.ipcc.ch/report/ar6/wg2/">A recent report</a> by the Intergovernmental Panel on Climate Change found that even in the best case, where the world halts warming at 1.5°C, sea levels could rise by <a href="https://www.wri.org/insights/ipcc-report-2022-climate-impacts-adaptation-vulnerability">0.55 metres</a> on average globally by 2100. This could lead to crippling storm surges in many places.</p>
<p>Paradoxically, these walls which are designed to protect people from the consequences of global heating also contribute to it. We estimated the emissions involved in creating north-eastern Japan’s concrete breakwaters at around six million tonnes of CO₂ by taking into account their size and length and using <a href="https://www.istructe.org/IStructE/media/Public/TSE-Archive/2020/A-brief-guide-to-calculating-embodied-carbon.pdf">industry-standard tools</a>.</p>
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<img alt="A coastal concrete wall covered in metal railings." src="https://images.theconversation.com/files/451378/original/file-20220310-25-sr3eox.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451378/original/file-20220310-25-sr3eox.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451378/original/file-20220310-25-sr3eox.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451378/original/file-20220310-25-sr3eox.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451378/original/file-20220310-25-sr3eox.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451378/original/file-20220310-25-sr3eox.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451378/original/file-20220310-25-sr3eox.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A reinforced coastal dike in north-eastern Japan, built following the 2011 tsunami.</span>
<span class="attribution"><span class="source">Ravindra Jayaratne</span>, <span class="license">Author provided</span></span>
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<p>So how can countries build stronger sea walls without making climate change worse? Following post-tsunami surveys of damaged breakwaters in southern Sri Lanka (2004) and north-eastern Japan (2011) with colleagues at Waseda University, and drawing from the University of East London’s low-carbon concrete research, we may have found an answer.</p>
<h2>Low-carbon concrete</h2>
<p>Concrete is the most common material for making breakwaters. Cement, the main binder in a concrete mix, is primarily made of clinker – a residue produced by firing limestone and clay in a furnace heated to 1,450°C. Creating that much heat is typically done by burning fossil fuels, emitting greenhouse gases in the process.</p>
<p>Cement making is responsible for about <a href="https://www.imperial.ac.uk/news/221654/best-ways-carbon-emissions-from-cement/">7% of annual CO₂ emissions</a>. But without concrete, many of the world’s most impressive buildings and structures – such as Australia’s Sydney Opera House and the Hoover Dam in Las Vegas – wouldn’t exist. One of the biggest challenges facing the construction sector is reducing concrete’s carbon footprint while keeping the <a href="https://sustainableconcrete.org.uk/Sustainable-Concrete/What-is-Concrete/Benefits-of-concrete.aspx">benefits</a> of a cheap and durable building material.</p>
<p>One way to achieve this is by replacing cement with recycled industrial waste, such as granulated slag from steelworks and pulverised ash from coal power plants (essentially, the residue that can be scraped out of the bottom of furnaces).</p>
<p>Our newly designed <a href="https://www.icevirtuallibrary.com/doi/10.1680/jensu.21.00021">low-carbon concrete mixes</a> use both of these recycled materials. In fact, it was possible to use up to 60% steel furnace waste in the mixes without the concrete losing its compressive strength, which is crucial for ensuring the structure holds up. The resulting mixes had a 40% smaller carbon footprint than traditional concrete.</p>
<p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0045794916303066?via=ihub">Our designs</a> also use steel fibres akin to hairpins that can be added to the concrete mix, eliminating the need to assemble vast steel mesh grids. The costs and emissions of construction are lower as a result, and the final product is just as strong as a traditional breakwater.</p>
<h2>Working with nature</h2>
<p>Concrete breakwaters can even <a href="https://biomimicry.org/examples/#construction">stimulate biodiversity</a>. Some are textured in such a way that they <a href="https://www.sensicon.co.uk/sensicrete-nature-based-solutions/">mimic reef habitats</a>, encouraging the settlement and growth of marine plants and animals in their grooves and protruding surfaces. </p>
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<span class="caption">This concrete recreates the shape and texture of coral and other reef species.</span>
<span class="attribution"><span class="source">Sensicon</span>, <span class="license">Author provided</span></span>
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<p>Over time, even the best-designed breakwaters will crack. Miraculously, engineers have developed self-healing concrete that uses <a href="https://www.basiliskconcrete.com/en/">microorganisms capable of producing limestone</a> to autonomously repair these structures. The idea of living organisms weaving through and repairing concrete, a material usually considered cold and lifeless, is very exciting to us. </p>
<p>There are likely to be even more sustainable concrete designs in the future, as 3D printing allows us to create more efficient patterns that use less material and produce less waste.</p>
<p>Using less to build more may worry <a href="https://theconversation.com/four-things-tsunami-vulnerable-countries-must-do-to-prepare-for-the-next-disaster-175721">coastal communities</a> which live in fear of tsunamis, as sustainable breakwaters are likely to be thinner, smaller and curved instead of straight. Yet these structures are just as strong and show that the world can adapt to the effects of climate change without making it worse.</p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p class="fine-print"><em><span>Ravindra Jayaratne receives funding from the Great Britain Sasakawa Foundation (GBSF) and Waseda University, Japan. </span></em></p><p class="fine-print"><em><span>Ali Abbas does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New breakwater designs and more sustainable materials can cut the carbon cost of coastal defences by 40%.Ravindra Jayaratne, Reader in Coastal Engineering, University of East LondonAli Abbas, Associate Professor of Structural Engineering, University of East LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1650762021-07-28T12:23:30Z2021-07-28T12:23:30ZA 20-foot sea wall won’t save Miami – how living structures can help protect the coast and keep the paradise vibe<figure><img src="https://images.theconversation.com/files/413417/original/file-20210727-19-aghe22.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C5138%2C3404&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Miami and Miami Beach were built right up to the waterfront, with little room for nature.</span> <span class="attribution"><a class="source" href="http://gettyimages.com/detail/photo/brickell-downtown-at-dusk-miami-royalty-free-image/545481008">Shobeir Ansari via Getty Images</a></span></figcaption></figure><p>Miami is all about the water and living life outdoors. Walking paths and parks line large stretches of downtown waterfront with <a href="https://www.youtube.com/watch?v=l6ARnAMZvWE">a stunning bay view</a>.</p>
<p>This downtown core is where the Army Corps of Engineers plans to build a <a href="https://www.saj.usace.army.mil/MiamiDadeBackBayCSRMFeasibilityStudy/">US$6 billion sea wall</a>, 20 feet high in places, through downtown neighborhoods and right between the Brickell district’s high-rises and the bay.</p>
<p>There’s no question that the city is at increasing risk of flooding as sea level rises and storms intensify with climate change. A hurricane as powerful as <a href="https://www.nhc.noaa.gov/1992andrew.html">1992’s Andrew</a> or <a href="https://www.nhc.noaa.gov/data/tcr/AL112017_Irma.pdf">2017’s Irma</a> making a direct hit on Miami <a href="https://www.nature.com/articles/s41893-018-0165-2?WT.feed_name=subjects_economics">would devastate the city</a>.</p>
<p>But the sea wall <a href="https://www.saj.usace.army.mil/MiamiDadeBackBayCSRMFeasibilityStudy/">the Army Corps is proposing</a> – protecting only 6 miles of downtown and the financial district from a storm surge – can’t save Miami and Dade County. Most of the city will be outside the wall, unprotected; the wall will still trap water inside; and the Corps hasn’t closely studied what the construction of a <a href="https://www.nap.edu/read/25853/chapter/1#xiii">high sea wall would do to water quality</a>. At the same time, it would block the water views that the city’s economy thrives on.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/413077/original/file-20210726-15-4ufzog.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An aerial view of downtown Miami showing waterfront walking paths, parks and pools" src="https://images.theconversation.com/files/413077/original/file-20210726-15-4ufzog.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/413077/original/file-20210726-15-4ufzog.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413077/original/file-20210726-15-4ufzog.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413077/original/file-20210726-15-4ufzog.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413077/original/file-20210726-15-4ufzog.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413077/original/file-20210726-15-4ufzog.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413077/original/file-20210726-15-4ufzog.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Much of Miami is built right up to the water’s edge. On average, it’s 6 feet above sea level.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/mqpawAQXRyA">Ryan Parker/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>To protect more of the region without losing Miami’s vibrant character, there are ways to pair the strength of less obtrusive hardened infrastructure with nature-based “green” solutions. With our colleagues at the <a href="https://welcome.miami.edu/">University of Miami</a>’s <a href="https://www.rsmas.miami.edu/">Rosenstiel School of Marine and Atmospheric Science</a> and the <a href="https://www.coe.miami.edu/">College of Engineering</a>, <a href="https://scholar.google.com/citations?user=kCFzlWIAAAAJ&hl=en">we have been</a> <a href="https://scholar.google.com/citations?user=hB5sJpoAAAAJ&hl=en">designing and testing</a> innovative hybrid solutions.</p>
<h2>Natural storm management</h2>
<p>Living with water today doesn’t look the same as it did 50 years ago, or even 20 years ago. Parts of Miami now regularly see “sunny day” flooding during high tides. Salt water infiltrates basements and high-rise parking garages, and tidal flooding is forecast to <a href="https://knowledge.uli.org/reports/research-reports/2020/the-business-case-for-resilience-in-southeast-florida">occur more frequently as sea level rises</a>. When storms come through, the storm surge adds to that already high water.</p>
<p>Hurricanes are less common than tidal flooding, but their <a href="https://www.ncdc.noaa.gov/billions/dcmi.pdf">destructive potential is greater</a>, and that is what the Army Corps is focused on with its sea wall plan. </p>
<p>If Miami Beach were an undeveloped barrier island, and if thick mangrove forests were still common along the South Florida shoreline, the Miami area would have more natural protection against storm surge and wave action. But most of those living buffers are long gone.</p>
<p>There are still ways nature can help preserve the beauty of Miami’s marine playground, though.</p>
<p>For example, <a href="https://www.usgs.gov/centers/pcmsc/science/value-us-coral-reefs-risk-reduction?qt-science_center_objects=0">healthy coral reefs break waves,</a> dissipating their energy before the waves reach shore. Dense mangrove forests also dissipate wave energy with their complex root systems that rise above the water line, <a href="https://www.sciencedirect.com/science/article/pii/S2212670813000079">dramatically reducing the waves’ impact</a>. In areas where coastal flooding is an increasing problem, low-lying communities can be <a href="https://theconversation.com/managed-retreat-done-right-can-reinvent-cities-so-theyre-better-for-everyone-and-avoid-harm-from-flooding-heat-and-fires-163052">relocated to higher ground</a> and the vacant land turned into wetlands, canals or <a href="https://www.fastcompany.com/90458827/how-these-new-orleans-nuns-helped-turn-their-convent-into-a-beautiful-flood-preventing-urban-wetland">parks that are designed to manage storm surge flooding</a>.</p>
<figure class="align-center ">
<img alt="Fish swim through the sea plants growing on a coral reef." src="https://images.theconversation.com/files/413084/original/file-20210726-24-hrhu63.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/413084/original/file-20210726-24-hrhu63.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413084/original/file-20210726-24-hrhu63.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413084/original/file-20210726-24-hrhu63.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413084/original/file-20210726-24-hrhu63.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413084/original/file-20210726-24-hrhu63.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413084/original/file-20210726-24-hrhu63.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Coral reefs like these in Biscayne National Park provide habitat and storm protection.</span>
<span class="attribution"><a class="source" href="https://www.nps.gov/media/photo/gallery-item.htm">National Park Service</a></span>
</figcaption>
</figure>
<p><iframe id="dVOZl" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/dVOZl/3/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Each area of coastline is unique and requires different protective measures based on the dynamics of how the water flows in and out. Given Miami’s limited space, living shorelines alone <a href="https://doi.org/10.18451/978-3-939230-64-9_122">won’t be enough</a> against a major hurricane, but there are powerful ways to pair them with solid “gray” infrastructure that are more successful than either alone.</p>
<h2>Hybrid solutions mix green and gray</h2>
<p>Nobody wants to look at a cement breakwater offshore. But if you’re looking at a breakwater covered with corals and hospitable to marine life, and you can go out and swim on it, that’s different. </p>
<p>Corals help the structure dissipate wave energy better, and at the same time they improve water quality, habitat, recreation, tourism and quality of life. For a lot of people, those are some of Miami’s main selling points.</p>
<p>By pairing corals and mangroves with a more sustainable and eco-friendly hard infrastructure, hybrid solutions can be far less obtrusive than a tall sea wall. </p>
<p>For example, a cement-based breakwater structure submerged offshore with coral transplants could provide habitat for entire ecosystems while <a href="https://doi.org/10.1002/lom3.10400">providing protection</a>. We’re working with the city of Miami Beach through the <a href="https://ulink.miami.edu/">University of Miami Laboratory for Integrative Knowledge</a> to <a href="https://www.facebook.com/cityofmiamibeach/videos/286963622974642/">implement three hybrid coral reefs just offshore</a> that we will monitor for their engineering and ecological performance.</p>
<p>Closer to shore, we’re experimenting with <a href="https://doi.org/10.18451/978-3-939230-64-9_122">a novel modular marine and estuarine system</a> we call “SEAHIVE.” Below the water line, water flows through hollow hexagonal channels of concrete, losing energy. The top can be filled with soil to grow coastal vegetation such as mangroves, providing even more protection as well as an ecosystem that benefits the bay.</p>
<figure class="align-center ">
<img alt="An illustration a marine park with SEAHIVE structures and people swimming nearby." src="https://images.theconversation.com/files/413062/original/file-20210726-21-1uqt09z.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/413062/original/file-20210726-21-1uqt09z.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413062/original/file-20210726-21-1uqt09z.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413062/original/file-20210726-21-1uqt09z.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413062/original/file-20210726-21-1uqt09z.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413062/original/file-20210726-21-1uqt09z.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413062/original/file-20210726-21-1uqt09z.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The SEAHIVE design combines hollow channels of concrete with mangroves above and corals below for natural protection.</span>
<span class="attribution"><a class="source" href="https://sustain.rsmas.miami.edu/research/projects/seahive-sustainable-estuarine-marine-revetment/index.html">Gallo Herbert Architects</a></span>
</figcaption>
</figure>
<p>We’re currently working on testing SEAHIVE as a green engineering alternative for riprap in North Bay Village, an inhabited island in the bay, and as infrastructure in a <a href="https://issuu.com/lighthousepointmagazine/docs/pom_june_21_web">newly developed marine park</a> in Pompano Beach called Wahoo Bay, developed in collaboration with local governments and Shipwreck Park, a not-for-profit organization. </p>
<h2>What about the rest of Miami?</h2>
<p>The Army Corps of Engineers’ <a href="https://www.saj.usace.army.mil/MiamiDadeBackBayCSRMFeasibilityStudy/">draft plan</a> – a final version is expected in the fall – would give nature-based solutions little role beyond a fairly <a href="https://usace.contentdm.oclc.org/utils/getfile/collection/p16021coll7/id/17747">small mangrove and sea grass restoration project</a> to the south. The Corps determined that natural solutions alone would require too much space and wouldn’t be as effective as hard infrastructure in a worst-case scenario.</p>
<p>Instead, the Army Corps’ plan focuses on the 6-mile sea wall, flood gates and elevating or strengthening buildings. It basically protects the downtown infrastructure but leaves everyone else on their own. </p>
<p>Sea walls and flood gates can also affect water flow and harm water quality. The Corps’ own <a href="https://usace.contentdm.oclc.org/utils/getfile/collection/p16021coll7/id/14453">documents warn</a> that the sea walls and gates will affect wildlife and ecosystems, including permanent loss of protective corals, mangroves and sea grass beds.</p>
<figure class="align-center ">
<img alt="A closeup shot of mangrove roots at the waterline" src="https://images.theconversation.com/files/413073/original/file-20210726-23-1wdpxzk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/413073/original/file-20210726-23-1wdpxzk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413073/original/file-20210726-23-1wdpxzk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413073/original/file-20210726-23-1wdpxzk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413073/original/file-20210726-23-1wdpxzk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413073/original/file-20210726-23-1wdpxzk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413073/original/file-20210726-23-1wdpxzk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mangrove roots rising above the water help break up the energy of waves at the shoreline.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/2Bdln1-BtUA">Florida Guidebook/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We would like to see a plan for all of Miami-Dade County that considers the value that green and hybrid solutions bring for marine life, tourism, fishing and general quality of life, in addition to their protective services for the shoreline.</p>
<p>Both types – green and gray – would take time to build out, particularly if the sea wall plan were challenged in court. And both run a risk of failure. Corals can die in a heat wave, and a storm can damage mangroves; but storms can also undermine engineered solutions, like the New Orleans levee system during Hurricane Katrina. To help build resilience, our colleagues at the University of Miami have been <a href="https://news.miami.edu/rsmas/stories/2021/05/scientists-successfully-breed-corals-with-goal-of-disease-resistance.html">breeding corals</a> to be more resistant to climate change, investigating novel cementitious materials and noncorrosive reinforcements and developing <a href="https://meridian.allenpress.com/jcr/article-abstract/37/3/656/450978/Multifunctional-Performance-of-Coastal-Structures">new designs for coastal structures</a>.</p>
<h2>Miami in the future</h2>
<p>Miami will be different in the coming decades, and the changes are already starting.</p>
<p>High ground is at a premium, and that’s showing up in real estate decisions that are pushing lower-income residents out and into less safe areas. Anybody looking back at Miami will probably think the region should have done a better job of managing growth and maybe even <a href="https://theconversation.com/managed-retreat-done-right-can-reinvent-cities-so-theyre-better-for-everyone-and-avoid-harm-from-flooding-heat-and-fires-163052">managing some form of retreat</a> from threatened areas.</p>
<p>We don’t want to see Miami become Venice or a city walled off from the water. We think Miami can thrive by making use of the local ecosystem with novel green engineering solutions and an architecture that adapts.</p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/165076/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Landolf Rhode-Barbarigos receives funding from the National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) for the research and development of the SEAHIVE - Sustainable Estuarine and Marine Revetment.</span></em></p><p class="fine-print"><em><span>Brian Haus receives funding from the National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) for the research and development of the SEAHIVE - Sustainable Estuarine and Marine Revetment.</span></em></p>The Army Corps of Engineers is planning a sea wall 6 miles long and flood gates. The infrastructure might protect downtown from a hurricane storm surge, but most of the area will still be vulnerable.Landolf Rhode-Barbarigos, Assistant Professor of Civil, Architectural and Environmental Engineering, University of MiamiBrian Haus, Professor of Ocean Sciences, University of MiamiLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1514582021-01-14T21:59:46Z2021-01-14T21:59:46ZNew mangrove forest mapping tool puts conservation in reach of coastal communities<figure><img src="https://images.theconversation.com/files/378676/original/file-20210113-17-1rltit9.jpg?ixlib=rb-1.1.0&rect=98%2C57%2C5259%2C3517&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mangroves, like these in Madagascar, provide a range of benefits, including protection from storms and the prevention of coastal erosion.</span> <span class="attribution"><span class="source">(Louise Jasper/Blue Ventures)</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Mangroves are salt-tolerant plants found in intertidal areas throughout much of the world’s <a href="https://data.unep-wcmc.org/datasets/4">tropical and subtropical coastlines</a>. Mangrove ecosystems are highly variable, ranging from sparse, stunted shrubs to dense stands of thick-stemmed tall trees. </p>
<p>These ecosystems provide habitat for an incredibly diverse <a href="https://doi.org/10.1016/j.aquabot.2007.12.007">range of species</a> including fish (from snapper to shark), invertebrates (such as shrimp and crab), reptiles (from snakes to crocodiles), birds (from kingfishers to hawks), primates (such as macaques and lemurs) and even Bengal tigers. </p>
<p>Mangroves also provide <a href="https://www.unep-wcmc.org/resources-and-data/the-importance-of-mangroves-to-people--a-call-to-action">essential goods and services</a> to millions living in coastal communities — they prevent shoreline erosion, provide protection from storms, supply food, cooking and building materials, and contain places of cultural and spiritual significance. They are also <a href="https://doi.org/10.1038/ngeo1123">incredibly carbon dense</a> storing as much or more carbon than their terrestrial forest peers — the majority of this carbon is stored in incredibly deep soils. </p>
<figure class="align-center ">
<img alt="Two women holding a GPS unit aloft near a mangrove" src="https://images.theconversation.com/files/378724/original/file-20210114-14-6h591c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378724/original/file-20210114-14-6h591c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378724/original/file-20210114-14-6h591c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378724/original/file-20210114-14-6h591c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378724/original/file-20210114-14-6h591c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378724/original/file-20210114-14-6h591c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378724/original/file-20210114-14-6h591c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Community members using GPS to map mangrove forest in Lamboara, Madagascar.</span>
<span class="attribution"><span class="source">(Garth Cripps/Blue Ventures)</span></span>
</figcaption>
</figure>
<p>Despite their obvious value, aquaculture, agriculture, urban development and unmanaged harvest are converting mangrove ecosystems across much of the tropics. Approximately <a href="https://doi.org/10.1641/0006-3568(2001)051%5B0807:MFOOTW%5D2.0.CO;2">35 per cent of global mangrove cover was lost</a> in the 1980s and ‘90s. While the rate of loss slowed in the past two decades — to an estimated <a href="https://doi.org/10.1038/s41467-020-18118-z">four per cent between 1996 and 2016</a> — many regions remain hotspots for mangrove loss, <a href="https://www.mdpi.com/2072-4292/11/6/728">including Myanmar</a>.</p>
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<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>This story is part of <a href="https://theconversation.com/uk/topics/oceans-21-96784">Oceans 21</a></em></strong>
<br><em>Our series on the global ocean opened with <a href="https://oceans21.netlify.app/">five in depth profiles</a>. Look out for new articles on the state of our oceans in the lead up to the UN’s next climate conference, COP26. The series is brought to you by The Conversation’s international network.</em></p>
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<p>My colleagues and I use satellite imagery and field measurements to study mangrove ecosystems in several countries. We’ve developed an accessible and intuitive tool that provides coastal managers with the accurate, reliable, up-to-date and locally relevant information they need for effective community-based conservation of these critical <a href="https://discover.blueventures.org/blue-forests/">blue (marine) forests</a>. </p>
<h2>New mangrove mapping tool</h2>
<p>Until now, information from satellite imagery on mangrove extent and change was either global in coverage and not intended for the smaller areas typically covered by community-based conservation efforts, or — if focused on a local scale — required substantial and costly technical expertise. </p>
<p>As a result, local resource managers often lacked the detail they need to effectively plan for the conservation, restoration and managed-use of mangrove forests, and tap into <a href="https://www.cifor.org/publications/pdf_files/Books/BFripp1401.pdf">payments for ecosystem services (PES)</a> programs, and the wealth of climate finance available for forest and <a href="https://doi.org/10.1016/j.marpol.2015.12.020">blue carbon initiatives</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/378679/original/file-20210113-13-hq7tjy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378679/original/file-20210113-13-hq7tjy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378679/original/file-20210113-13-hq7tjy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378679/original/file-20210113-13-hq7tjy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378679/original/file-20210113-13-hq7tjy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378679/original/file-20210113-13-hq7tjy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378679/original/file-20210113-13-hq7tjy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Community mangrove mapping in Lamboara, Madagascar.</span>
<span class="attribution"><span class="source">(Garth Cripps/Blue Ventures)</span></span>
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</figure>
<p>Our new tool — the Google Earth Engine Mangrove Mapping Methodology (<a href="https://www.mdpi.com/2072-4292/12/22/3758">GEEMMM</a>) makes this information freely available to coastal managers and covers the smaller areas they’re concerned with. </p>
<p>The need for a tool like this is enormous. Global products like the <a href="https://www.globalmangrovewatch.org/">Global Mangrove Watch</a> are not intended for local use. And the conventional methods required for local mapping involve a range of technical hurdles including data availability, data processing techniques, computing power and specialized software. All of this remains well beyond the scope of most locally led conservation project budgets. </p>
<p>Our new tool bypasses these barriers and offers an accessible approach to non-specialists including a comprehensive, step-by-step workflow. It requires no specialized expertise with satellite imagery, data processing or coding. The tool only requires basic computer skills, a relatively stable internet connection, and an understanding of the key steps for mapping mangroves. </p>
<h2>Piloting the new tool</h2>
<p>To pilot our new mangrove mapping tool, we used Myanmar — a <a href="https://www.mdpi.com/2072-4292/11/6/728">global loss hotspot</a> — as a case study. This loss is mostly happening due to widespread conversion for agriculture, such as rice, oil palm and rubber, and for aquaculture, primarily shrimp. </p>
<p>The tool produces current and historic maps of mangrove extent, assesses the quantitative and qualitative accuracy of these maps, and calculates the amount of change that has occurred within a given area of concern. Our results show an alarming 35 per cent loss of mangroves throughout coastal Myanmar since 2004.</p>
<figure class="align-center ">
<img alt="Satellite images showing mangrove deforestation." src="https://images.theconversation.com/files/378720/original/file-20210114-24-150ul7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378720/original/file-20210114-24-150ul7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=626&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378720/original/file-20210114-24-150ul7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=626&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378720/original/file-20210114-24-150ul7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=626&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378720/original/file-20210114-24-150ul7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=787&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378720/original/file-20210114-24-150ul7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=787&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378720/original/file-20210114-24-150ul7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=787&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Mangrove loss in Rakhine State, Myanmar, along the SE coast of Ramree Island and W coast of Taungup Township. The left panels (1) show historic Landsat satellite imagery, ca. 2004-08, and the right panels (2) show contemporary imagery, ca. 2014-18. The top panels (a) show landscape features appear as they would in a regular colour photograph, while the bottom panels (b) show a false colour composite, which provides additional contrast. The mangroves are most easily identifiable in the false colour composite as the dark red regions close to the water. In this 10-year window, large swaths of mangroves have clearly been deforested.</span>
<span class="attribution"><span class="source">(Trevor Gareth Jones)</span>, <span class="license">Author provided</span></span>
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<p>My colleagues in Madagascar are further testing the new tool along the country’s west coast where <a href="https://blueventures.org/new-research-mapping-madagascars-mangroves/">21 per cent of the island’s mangroves — an area equivalent in size to 80,000 soccer fields — were lost between 1990 and 2010</a>. </p>
<p>Mangroves are a threatened ecosystem in Madagascar, and understanding where they are — and how they’re being used — is crucial for coastal communities. “These communities need to be supported with the use of a simple monitoring tool that is adaptable to the local context,” said Cicelin Rakotomahazo, the coordinator for Blue Forests in Andavadoaka, Madagascar.</p>
<p>Our new mangrove mapping tool is <a href="https://github.com/Blue-Ventures-Conservation/GEEMMM">freely accessible online</a> to non-profit users and runs in Google Earth Engine with detailed instructions. The tool offers locally relevant information and removes key technical barriers for use, providing a ready-to-go approach through which coastal managers can use their local knowledge to map mangrove ecosystems anywhere they are found. Those using the tool also play a role in testing and shaping its development. </p>
<p>Healthy mangroves protect people from waves and storms, prevent coastal erosion, and serve as a nursery for fish and invertebrates. They provide shelter for local and migratory birds, and hunting grounds for primates and reptiles. They store significant amounts of carbon, making serious contributions towards global climate change mitigation. </p>
<p>The communities that live in and around mangrove ecosystems are their biggest advocates, and this new mangrove mapping tool (GEEMMM) offers a tangible contribution towards local mangrove conservation, restoration and managed use.</p><img src="https://counter.theconversation.com/content/151458/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Trevor Gareth Jones works for Blue Ventures Conservation, the conservation NGO in charge of this project. </span></em></p>Despite their enormous value, mangroves are being removed at an alarming rate. A new tool aims to help communities reverse mangrove loss and tap into conservation programs and funding.Trevor Gareth Jones, Adjunct Professor of Forest Resources Management and MGEM Program Advisor, University of British ColumbiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1494352020-12-31T00:12:59Z2020-12-31T00:12:59ZLeft to ruin: we must preserve our forgotten wartime defences<figure><img src="https://images.theconversation.com/files/373252/original/file-20201207-15-1i3dsh9.jpg?ixlib=rb-1.1.0&rect=193%2C126%2C3814%2C2504&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fort Drummond at Mount Saint Thomas, NSW.</span> <span class="attribution"><span class="source">Alexander Lee</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Australia built a number of coastal defences to help protect the country from any enemy attack during the second world war. Now, almost 80 years later, some of the physical remnants of those historic facilities lie forgotten and decaying.</p>
<p>These monuments to the nation’s home defence are in desperate need of preservation. While their condition varies greatly, too many have faded into obscurity.</p>
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Read more:
<a href="https://theconversation.com/what-happens-now-weve-found-the-site-of-the-lost-australian-freighter-ss-iron-crown-sunk-in-wwii-115848">What happens now we've found the site of the lost Australian freighter SS Iron Crown, sunk in WWII</a>
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<h2>In defence of Wollongong</h2>
<p>For example, if you take a drive through the city of Wollongong today you could be forgiven for thinking the city played no role in the war. There is little indication this city was once heavily defended against a much-feared Axis attack. </p>
<p>If you take a 15-minute drive south of the city centre you’ll find some remnants of the city’s home defences. The well-developed Port Kembla Heritage Park, with its cluster of tank traps and ruined gun instalments, alludes to the history of a city that was once extremely important to Australia’s war effort.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/374133/original/file-20201210-14-nx3mfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Small concrete pyramids designed to stop tanks." src="https://images.theconversation.com/files/374133/original/file-20201210-14-nx3mfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/374133/original/file-20201210-14-nx3mfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/374133/original/file-20201210-14-nx3mfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/374133/original/file-20201210-14-nx3mfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/374133/original/file-20201210-14-nx3mfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/374133/original/file-20201210-14-nx3mfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/374133/original/file-20201210-14-nx3mfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The pyramid tank traps at Port Kembla.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/yewenyi/1180069069/">Brian Yap/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
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<p>This site, known as <a href="https://www.environment.nsw.gov.au/heritageapp/ViewHeritageItemDetails.aspx?ID=2700585">Breakwater Battery</a>, was the first, smallest and weakest of three interconnected strongpoints designed to defend the industry of the Illawarra region of New South Wales from attack.</p>
<p>But this raises the question: where are the other two stronger points of Wollongong’s defensive network? </p>
<h2>Our hidden defences</h2>
<p>These sites still exist but are hidden. If you head to the leafy suburb of Mount Saint Thomas or Hill 60 Park in Port Kembla, you will find the more impressive remnants of the city’s defences. </p>
<p>Mount Saint Thomas and Hill 60 Park once hosted the military centres of <a href="https://www.environment.nsw.gov.au/heritageapp/ViewHeritageItemDetails.aspx?ID=2700709">Fort Drummond</a> and the <a href="https://www.environment.nsw.gov.au/heritageapp/ViewHeritageItemDetails.aspx?ID=5052361">Illowra Battery</a> respectively.</p>
<p>Dug into the hillside in both locations are impressive concrete casemates that once housed powerful naval guns. Hundreds of men and huge amounts of Australia’s limited wartime resources were dedicated to building and staffing these sites in the wartime period from 1941-1942.</p>
<p>The Illowra Battery, sitting right on the coast, was designed to replace Breakwater Battery as the pivot of local defences. It was strengthened over time with barbed wire, radar and tunnels deep in the hillside.</p>
<p>In the case of Fort Drummond, the 9.2-inch coastal guns were originally slated to be installed in Darwin in the Northern Territory, but were diverted south to strengthen the defences of Wollongong.</p>
<p>The prioritisation of the defence of Wollongong over Darwin, which was <a href="https://www.awm.gov.au/collection/E84294">bombed</a>, shows just how important protecting this southern region was. </p>
<p>The three strong points were designed to operate in concert to defend the region from an attack on Australia’s manufacturing core.</p>
<p>The industrial Illawarra was an economic behemoth for wartime Australia, producing everything from bullets to aircraft parts. It exported the materials of war across the British Empire, as far away as England and Singapore, and alongside Newcastle (in NSW) was the heart of Australian industry. </p>
<p>Yet, despite their important role in the war, these monuments are now overgrown, slowly being reclaimed by nature.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/374141/original/file-20201210-23-tfqh35.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An overgrown site of one of the coast al defences." src="https://images.theconversation.com/files/374141/original/file-20201210-23-tfqh35.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/374141/original/file-20201210-23-tfqh35.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/374141/original/file-20201210-23-tfqh35.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/374141/original/file-20201210-23-tfqh35.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/374141/original/file-20201210-23-tfqh35.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/374141/original/file-20201210-23-tfqh35.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/374141/original/file-20201210-23-tfqh35.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Illowra Battery exterior: the entrance is heavily overgrown and the path to the site is undeveloped.</span>
<span class="attribution"><span class="source">Alexander Lee</span>, <span class="license">Author provided</span></span>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/lest-we-forget-our-other-heroes-of-war-fighting-for-freedom-at-home-38428">Lest we forget our other heroes of war, fighting for freedom at home</a>
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<h2>Kept in the dark</h2>
<p>In the 1960s and early 1970s, the dark tunnels of Fort Drummond were converted to mushroom farms, not military history attractions.</p>
<p>As for Hill 60, instead of being developed as a tourist attraction the place has appeared on lists of the most <a href="https://www.illawarramercury.com.au/story/4815089/8-of-the-most-haunted-places-in-the-illawarra-and-south-coast/">haunted places in the Illawarra</a>.</p>
<p>Reports five years ago that Hill 60 would be <a href="https://www.illawarramercury.com.au/story/3272312/plan-to-reopen-port-kemblas-wartime-tunnels/">redeveloped</a>, opening the tunnels, adding signage and highlighting the area’s Aboriginal history, have come to nothing. </p>
<p>Such stories of neglect are repeated at other defence sites across Australia.</p>
<p>Significant sites in <a href="https://www.dailytelegraph.com.au/news/nsw/ghostly-network-of-concrete-bunkers-once-home-to-sydneys-coastal-defence-in-wartime/news-story/26232d5453d3dddb4061c8a28d7083ea">Sydney</a>, <a href="https://apps.des.qld.gov.au/heritage-register/detail/?id=602559">Brisbane</a>, <a href="https://www.abc.net.au/news/2019-01-01/inside-adelaides-remaining-world-war-bunkers/10562188">Adelaide</a> and <a href="https://www.newcastleherald.com.au/story/4077142/fort-wallace-revealed-photos/">Newcastle</a> are dilapidated and eroding.</p>
<p>Even in areas of historical significance to Australia, where the country’s colonial history has been well preserved, such as the Sydney suburb of <a href="https://www.sydney.com/destinations/sydney/sydney-east/la-perouse/attractions/bare-island-fort">La Perouse</a>, the nearby second world war artillery battery sites and lookout posts are <a href="https://www.tracesofwar.com/sights/8059/Battery-Henry-Head.htm">neglected</a>.</p>
<p>Considering these sites are often in idyllic locations and — by necessity at the time they were built — boast impressive ocean views, it is odd their value, even as tourist sites, remains unrealised.</p>
<p>There are other sites across Australia that have received investment in preservation, such as <a href="https://fortlytton.org.au/">Fort Lytton</a> in Brisbane and <a href="https://www.newcastle.nsw.gov.au/fort-scratchley/fort-scratchley-home">Fort Scratchley</a> in Newcastle. These are now tourist destinations. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-cowra-breakout-remembering-and-reflecting-on-australias-biggest-prison-escape-75-years-on-120410">The Cowra breakout: remembering and reflecting on Australia's biggest prison escape 75 years on</a>
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<p>With relatively small investments the neglected sites could be made more accessible. The public would then be able to learn and understand their history and significance.</p>
<p>Signposting, basic repairs and publicising these important relics of our wartime history would be easy first steps to revive public interest in these locations. </p>
<p>The educational and touristic values of Australia’s second world war defences are readily apparent. All they require is a little bit of attention after so many decades of neglect.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/374144/original/file-20201210-18-e2qpr9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Plenty of graffiti just inside the coastal defence site." src="https://images.theconversation.com/files/374144/original/file-20201210-18-e2qpr9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/374144/original/file-20201210-18-e2qpr9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/374144/original/file-20201210-18-e2qpr9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/374144/original/file-20201210-18-e2qpr9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/374144/original/file-20201210-18-e2qpr9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/374144/original/file-20201210-18-e2qpr9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/374144/original/file-20201210-18-e2qpr9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Inside the Illowra Battery graffiti covers the walls next to the tunnels, visible behind metal bars.</span>
<span class="attribution"><span class="source">Alexander Lee</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/149435/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alexander Mitchell Lee receives funding from the Australian Government's Research Training Program Scholarship for his Higher Education by Research studies.</span></em></p>Some of our coastal defences are in desperate need of preservation and could be transformed into tourist attractions.Alexander Mitchell Lee, PhD Candidate, Crawford School of Public Policy, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1324242020-03-10T14:21:54Z2020-03-10T14:21:54ZProtecting mangroves can prevent billions of dollars in global flooding damage every year<figure><img src="https://images.theconversation.com/files/319361/original/file-20200309-118960-1p59j7b.jpeg?ixlib=rb-1.1.0&rect=11%2C0%2C3864%2C2609&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mangroves along Mexico's Yucatan coastline.</span> <span class="attribution"><span class="source">Michael Beck</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Hurricanes and tropical storms are estimated to cost the U.S. economy <a href="https://www.cbo.gov/system/files/2019-04/55019-ExpectedCostsFromWindStorm.pdf">more than US$50 billion yearly</a> in damage from winds and flooding. And as these storms travel across the Atlantic, they also ravage many Caribbean nations. </p>
<p>We study <a href="https://scholar.google.com/citations?user=fLXCUREAAAAJ&hl=en">coastal ecosystems</a> and how to <a href="https://scholar.google.es/citations?user=QB2RvcsAAAAJ&hl=es">value the natural coastal defenses</a> provided by <a href="https://coastalresilience.ucsc.edu/">mangroves, marshes and coral reefs</a>. In a new study, we <a href="https://doi.org/10.1038/s41598-020-61136-6">map flood risks</a> along more than 435,000 miles (700,000 kilometers) of subtropical shoreline in 59 countries around the world. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/319439/original/file-20200309-118890-pq5p3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/319439/original/file-20200309-118890-pq5p3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/319439/original/file-20200309-118890-pq5p3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=563&fit=crop&dpr=1 600w, https://images.theconversation.com/files/319439/original/file-20200309-118890-pq5p3b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=563&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/319439/original/file-20200309-118890-pq5p3b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=563&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/319439/original/file-20200309-118890-pq5p3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=707&fit=crop&dpr=1 754w, https://images.theconversation.com/files/319439/original/file-20200309-118890-pq5p3b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=707&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/319439/original/file-20200309-118890-pq5p3b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=707&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mangroves in Loxahatchee, Florida.</span>
<span class="attribution"><a class="source" href="https://oceanservice.noaa.gov/facts/mangroves.html">NOAA</a></span>
</figcaption>
</figure>
<p>Along these coasts, we calculate that flood risks exceed $730 billion annually in direct impacts to property. Many government agencies and insurers estimate that indirect impacts to livelihoods and other economic activity are <a href="https://doi.org/10.3133/ofr20191027">two to three times these direct flood costs</a>. </p>
<p>We also estimate that across these 59 countries, mangroves – salt-tolerant trees that grow along tropical coastlines worldwide – reduce risk to more than 15 million people and <a href="https://www.dropbox.com/s/4gma6k1zmtx6vnj/Mangrove%20Animation%20Copyright%20J.%20Kendall-Bar.mp4?dl=0">prevent more than $65 billion in property damages every year</a>. Mangroves do this by blocking <a href="https://oceanservice.noaa.gov/facts/stormsurge-stormtide.html">storm surge</a> – the rise in sea level during storms – and dampening waves, which protect people and structures near the shore. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/aoMrLYJOdA4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">This scale model shows how mangroves protect coastlines from wave action.</span></figcaption>
</figure>
<h2>Battered coastlines</h2>
<p>Tropical storms are a well-recognized hazard along many coasts. In 2019, which was an above-normal year for tropical storm activity, <a href="http://tropical.atmos.colostate.edu/Realtime/index.php?arch&loc=global">90 named storms</a> formed around the world, including 62 days with major tropical cyclones.</p>
<p>As one example, <a href="https://www.weather.gov/mhx/Dorian2019">Hurricane Dorian</a> devastated the northern Bahamas with sustained winds of some 185 miles per hour. Throughout its life, <a href="https://www.nhc.noaa.gov/archive/2019/DORIAN_graphics.php?product=wind_history">Dorian’s path</a> impacted more than 17 nations and 15 U.S. states and territories, from Grenada to Newfoundland. </p>
<p>And Dorian was not even the strongest cyclone of the year. That title went to <a href="https://blogs.nasa.gov/hurricanes/2019/11/06/halong-northwestern-pacific-ocean-3/">Super Typhoon Halong</a> in the Western Pacific, which steered clear of land. Many scientists predict that climate change will <a href="https://www.gfdl.noaa.gov/global-warming-and-hurricanes/">make these storms more intense</a>, with a likely increase in the proportion of storms that reach Categories 4 and 5.</p>
<p>It would be logical to assume that countries map the flood risks from these storms, since they have to protect residents who live near coasts, along with public infrastructure such as ports, airports, wastewater treatment centers and power plants. These facilities often are built in low-lying areas around urban and suburban centers.</p>
<p>However, governments and businesses only develop flood risk analyses for the shorelines of highly developed nations, where people have the resources to pay for or insure against these risks. This excludes most tropical countries, where many of the world’s most vulnerable people live.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/319472/original/file-20200309-118960-172ldcy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/319472/original/file-20200309-118960-172ldcy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/319472/original/file-20200309-118960-172ldcy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=213&fit=crop&dpr=1 600w, https://images.theconversation.com/files/319472/original/file-20200309-118960-172ldcy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=213&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/319472/original/file-20200309-118960-172ldcy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=213&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/319472/original/file-20200309-118960-172ldcy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=268&fit=crop&dpr=1 754w, https://images.theconversation.com/files/319472/original/file-20200309-118960-172ldcy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=268&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/319472/original/file-20200309-118960-172ldcy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=268&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tropical storm tracks since 1842.</span>
<span class="attribution"><a class="source" href="https://www.ncdc.noaa.gov/ibtracs/index.php?name=browse">NOAA</a></span>
</figcaption>
</figure>
<h2>Defending shorelines</h2>
<p>Our study was designed to quantify these flood risks worldwide and identify solutions for reducing them. We used tools that are standard in the insurance and engineering industries, along with a five-step approach for calculating expected damage, to develop high-resolution estimates of flood risk globally. Then we coupled spatially explicit hydrodynamic flood models with economics to estimate impacts to people and property.</p>
<p>We focused on mangroves because they are large trees that grow quickly in salt water at the edge of the coastal zone, where they form a front line of defense. Mangroves are also excellent at trapping sediments and building land. On average, land around mangroves grows vertically by <a href="https://www.conservationgateway.org/ConservationPractices/Marine/crr/library/Documents/mangrove-surface-elevation-and-sea-level-rise.pdf">1 to 10 millimeters per year</a>.</p>
<p>We generated maps summarizing the benefits that mangroves provide in 20-kilometer coastal units around the world. They show that there are 100 coastal areas where mangroves avert $100 million or more in property damages every year. These are clearly priority zones where mangrove conservation and restoration will yield highly cost-effective benefits to people, property and national budgets.</p>
<p>According to our estimates, the <a href="https://www.nature.com/articles/s41598-020-61136-6/tables/2">U.S., China and Taiwan</a> receive the greatest economic benefits – protection of property – from mangroves. Vietnam, India and Bangladesh receive the greatest social benefits – protection of people. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/319607/original/file-20200310-61120-26drkg.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/319607/original/file-20200310-61120-26drkg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/319607/original/file-20200310-61120-26drkg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=425&fit=crop&dpr=1 600w, https://images.theconversation.com/files/319607/original/file-20200310-61120-26drkg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=425&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/319607/original/file-20200310-61120-26drkg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=425&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/319607/original/file-20200310-61120-26drkg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=534&fit=crop&dpr=1 754w, https://images.theconversation.com/files/319607/original/file-20200310-61120-26drkg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=534&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/319607/original/file-20200310-61120-26drkg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=534&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Along some 20-kilometer coastal stretches, mangroves provide up to $500,000,000 in flood reduction benefits yearly.</span>
<span class="attribution"><span class="source">Michael Beck</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Mangroves as green infrastructure</h2>
<p>Mangrove destruction has been widespread, largely because of coastal development and aquaculture. From 1980 through the early 2000s, the world lost <a href="http://www.fao.org/newsroom/en/news/2008/1000776/index.html">up to 20% of existing mangrove habitat</a>. The rate of loss has slowed but still continues, driven by urban expansion, pollution and agriculture. </p>
<p>Given our findings about how valuable mangroves are for coastal protection, we believe they should be viewed as national infrastructure and made eligible for funding from hazard mitigation and disaster recovery budgets, just like other coastal defense structures. Paying for mangrove restoration can work through the same approaches that are currently used to fund engineered protective structures such as seawalls. </p>
<p>Several new studies done collaboratively with <a href="https://www.rms.com/">Risk Management Solutions</a>, a leading insurance risk modeling firm, show that coastal <a href="https://doi.org/10.1038/s41598-017-09269-z">marshes</a> and <a href="https://www.nature.org/content/dam/tnc/nature/en/documents/Mangrove_Report_digital_FINAL.pdf">mangroves</a> provide significant storm reduction benefits. These findings could underpin the development of innovative insurance options for natural systems. </p>
<p>Examples are already being developed for coral reefs in <a href="https://doi.org/10.3389/feart.2019.00125">Mexico</a> and <a href="https://doi.org/10.1016/j.ecolecon.2019.106487">across the Caribbean</a>. Conserving mangroves where they occur together with coral reefs can multiply the flood protection benefits from habitats. </p>
<p>Working with the World Bank, countries like the <a href="https://doi.org/10.1016/j.ecoser.2018.09.005">Philippines</a> and <a href="https://www.nepa.gov.jm/new/projects/docs/WorldBank2019_ForcesOfNature.pdf">Jamaica</a> are assessing how the benefits of mangroves can be <a href="https://www.wavespartnership.org/">incorporated into national finances</a>, disaster management and proposals for the <a href="https://www.greenclimate.fund/">U.N. Green Climate Fund</a>, which was created in 2010 to help developing countries mitigate greenhouse gas emissions and adapt to climate change. Our work was supported by the World Bank and Germany’s <a href="https://www.international-climate-initiative.com/en?iki_cookie_check=1">International Climate Initiative</a> to help inform solutions for nations that are most at risk.</p>
<p>In many places, preserving and restoring mangrove forests can be an extremely economically effective strategy for protecting coasts from tropical storm damage. As national governments and insurers grapple with disaster management costs that are <a href="https://www.munichre.com/topics-online/en/climate-change-and-natural-disasters/natural-disasters/overview-natural-catastrophe-2016.html">growing nearly exponentially worldwide</a>, we believe our research can create new opportunities to pay for mangrove conservation and restoration using climate adaptation, disaster risk reduction and insurance funds. </p>
<p>[<em>Get the best of The Conversation, every weekend.</em> <a href="https://theconversation.com/us/newsletters/weekly-highlights-61?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=weeklybest">Sign up for our weekly newsletter</a>.]</p><img src="https://counter.theconversation.com/content/132424/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Beck receives funding from The World Bank, the German International Climate Initiative, The Nature Conservancy, and AXA. </span></em></p><p class="fine-print"><em><span>Pelayo Menéndez Fernández has received funds from the FPI grant from the Ministry of Economy and Competitiveness of the Government of Spain.</span></em></p>A new study estimates that mangroves prevent over $65 billion in damage from coastal storms every year, and says mangrove protection should be funded in the same way as infrastructure like seawalls.Michael Beck, Research professor, University of California, Santa CruzPelayo Menéndez, Postdoctoral Fellow in Marine Science, University of California, Santa CruzLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1166362019-05-07T11:22:20Z2019-05-07T11:22:20ZCoral reefs provide flood protection worth $1.8 billion every year – it’s time to protect them<figure><img src="https://images.theconversation.com/files/272901/original/file-20190506-103063-388iue.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Underwater view of waves breaking over a healthy coral reef, reducing wave energy at the shoreline that can cause flooding.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/wSokCe">Curt Storlazzi, USGS</a></span></figcaption></figure><p>The news is grim: According to a report compiled by hundreds of scientists from 50 countries, Earth is losing species <a href="https://www.ipbes.net/">faster than at any other time in human history</a>. Thanks to climate change, coastal development and the impacts of activities such as logging, farming and fishing, roughly 1 million plants and animals are facing extinction.</p>
<p>The UN report calls for rapid action at every level, from local to global, to conserve nature and use it sustainably. And here’s some potential good news: Many ecosystems now at risk can provide valuable services if they are protected.</p>
<p>I know from <a href="https://scholar.google.com/citations?user=fLXCUREAAAAJ&hl=en">my research on coastal habitats</a> that the biggest obstacle to investing in natural infrastructure, such as wetlands and reefs, often is that experts have not figured out how to value the protection that these habitats provide in economic terms. But a <a href="https://pubs.er.usgs.gov/publication/ofr20191027">new report</a> that I co-authored, published by the <a href="https://www.usgs.gov/">U.S. Geological Survey</a>’s <a href="https://www.usgs.gov/natural-hazards/coastal-marine-hazards-and-resources">Coastal Hazards Program</a>, solves that problem for one of our planet’s most biodiverse ecosystems: coral reefs.</p>
<p>This report shows that coral reefs in U.S. waters, from Florida and the Caribbean to Hawaii and Guam, provide our country with more than US$1.8 billion dollars in flood protection benefits every year. They reduce direct flood damages to public and private property worth more than $800 million annually, and help avert other costs to lives and livelihoods worth an additional $1 billion. Rigorously valuing reef benefits in this way is the first step toward mobilizing resources to protect them. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/272907/original/file-20190506-103082-m6up2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272907/original/file-20190506-103082-m6up2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272907/original/file-20190506-103082-m6up2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272907/original/file-20190506-103082-m6up2u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272907/original/file-20190506-103082-m6up2u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272907/original/file-20190506-103082-m6up2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272907/original/file-20190506-103082-m6up2u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272907/original/file-20190506-103082-m6up2u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Healthy coral reefs with live coral provide much greater protection against coastal flooding than degraded reefs with low live coral cover.</span>
<span class="attribution"><a class="source" href="https://noaa.maps.arcgis.com/apps/MapSeries/index.html?appid=b0a4046c33d04a829bd41dfc3061502a">NOAA</a></span>
</figcaption>
</figure>
<h2>Breaking waves and blocking floods</h2>
<p>Reefs act just like submerged breakwaters. They “break” waves and drain away their energy offshore, before it floods coastal properties and communities. This is an enormously valuable function. In 2017, tropical storms alone did <a href="https://www.climate.gov/news-features/blogs/beyond-data/2017-us-billion-dollar-weather-and-climate-disasters-historic-year">over $265 billion in damage</a> across the nation. </p>
<p>Manmade defenses, such as sea walls, can <a href="https://pubs.usgs.gov/sir/2010/5254/pdf/sir20105254_chap7.pdf">damage adjoining habitats</a> and harm <a href="https://coastalscience.noaa.gov/news/shoreline-development-hardening-hurts-shorebirds-waterfowl/">species that rely on them</a>. In contrast, healthy reefs <a href="https://oceanservice.noaa.gov/education/kits/corals/coral07_importance.html">enhance their surroundings</a> by protecting shorelines and supporting fisheries and recreation, from diving to surfing. </p>
<p>The flood protection benefits that reefs provide across the U.S. are similar to those in more than 60 other nations. As I estimated with colleagues in a separate study, the global cost of storm damage to the world’s coastlines <a href="https://doi.org/10.1038/s41467-018-04568-z">would double without reefs</a>.</p>
<h2>Pinpointing local flood protection value</h2>
<p>Our estimate of the value of flood protection from reefs applies state-of-the-art tools that engineers and insurers use to assess flood risks and benefits.</p>
<p>Using a model and more than 60 years of hourly wave data for all U.S. states and territories with reefs – a total area of over 1,900 miles – we developed flood risk maps projecting the extent and depth of flooding that would occur across many storms, both regular and catastrophic, with reefs present and then without them. We calculated these values in grid cells that measured just 100 square meters, or about 1,000 square feet – the footprint of a small house. </p>
<p>Then we overlaid these flood risk maps on the latest information from the U.S. Census Bureau and the Federal Emergency Management Agency to identify people and properties at risk – and benefiting from the presence of reefs – in each location. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/272910/original/file-20190506-103071-rl76tm.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272910/original/file-20190506-103071-rl76tm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272910/original/file-20190506-103071-rl76tm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=461&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272910/original/file-20190506-103071-rl76tm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=461&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272910/original/file-20190506-103071-rl76tm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=461&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272910/original/file-20190506-103071-rl76tm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=580&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272910/original/file-20190506-103071-rl76tm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=580&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272910/original/file-20190506-103071-rl76tm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=580&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map showing the 100-year floodplains on south Maui, Hawai‘i. They show the flooding in a 1 in 100 year flood event with reefs at present (blue) and the extra flooding predicted (red) if we lost the topmost 1m (3 ft) of reef. The people and property under the red zone are those predicted to benefit by keeping reefs intact.</span>
<span class="attribution"><a class="source" href="https://pubs.er.usgs.gov/publication/ofr20191027">USGS</a></span>
</figcaption>
</figure>
<p>With this level of detail, we now can identify not just total benefits provided by reefs, but who receives them. For example, Florida receives more than $675 million in annual flood protection from reefs, and Puerto Rico gets $183 million in protection yearly. In Honolulu alone, we found that reefs provide more than $435 million in protection from a catastrophic 1-in-50-year storm – an event large enough that it would be expected to occur only once in a 50-year period.</p>
<p>It is well known that coral reefs are under heavy stress from climate change, which is warming oceans, causing <a href="https://theconversation.com/will-the-great-barrier-reef-recover-from-its-worst-ever-bleaching-67063">coral bleaching</a>. <a href="https://theconversation.com/how-fish-and-clean-water-can-protect-coral-reefs-from-warming-oceans-60434">Pollution and overfishing</a> are also doing serious damage. As the UN report on biodiversity loss notes, Earth has lost approximately half of its live coral reef cover since the 1870s. And that trend leaves 100-300 million people in coastal areas at increased risk due to loss of coastal habitat protection.</p>
<h2>Investing in natural defenses</h2>
<p>How can our valuation study inform coral reef protection? </p>
<p>First, it buttresses the case for using disaster recovery funding to help natural coastal defenses recover. After Hurricane Sandy in 2012, only about 1% of recovery funding went toward rebuilding natural resilience, despite subsequent research showing that marshes in the Northeast can <a href="https://doi.org/10.1038/s41598-017-09269-z">reduce flood damages by some 16% annually</a>. </p>
<p>More than $100 billion has been appropriated to recover from hurricanes Harvey, Maria and Irma; it would make economic sense to spend some of these funds on rebuilding reefs. In a promising move, the <a href="https://www.fema.gov/">Federal Emergency Management Agency</a> has created opportunities to include ecosystem services such as flood protection and fishery production in official <a href="https://www.fema.gov/media-library-data/1464289244246-28e881d6ae6f84f8666a165f83329456/Supp_BCA_Guid_Floodplain_StreamRest_508.pdf">benefit to cost analysis calculations</a> to support flood mitigation funding.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/N3nEzmT3I9M?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Coral reef restoration in Hawaii starts with changing land management practices to reduce erosion.</span></figcaption>
</figure>
<p>Second, the insurance industry has an important role to play in offering incentives and supporting investments in nature-based defenses for risk reduction. Insurers are starting to <a href="https://doi.org/10.1038/s41598-017-09269-z">consider habitats in industry risk models</a> and <a href="https://www.reuters.com/article/us-mexico-environment-reefs/mexican-coral-reef-and-beach-get-unique-insurance-policy-against-hurricane-damage-idUSKCN1GK384">to create opportunities to insure nature</a>. Thus reefs could be re-built if they are damaged in storms or even restored now based on their proven flood protection (i.e., premium saving) benefits.</p>
<p>Third, federal agencies have incentives to invest in reefs as protection for critical infrastructure. Reefs defend military bases located along tropical coastlines, as well as shore-hugging roads that are the lifeblood of many economies from Hawaii to Florida and Puerto Rico.</p>
<p>Through its <a href="https://ewn.el.erdc.dren.mil/currentprojects.html">Engineering With Nature</a> initiative, the Army Corps of Engineers is making more use of natural solutions to minimize flood risks. And the U.S. Department of Transportation is analyzing ways to <a href="https://ewn.el.erdc.dren.mil/workshops/2018_07-29-NNBF-short-course/ppt/1145-1205_Hodges-NNBFTransportationCaseStudy.pdf">protect coastal highways with nature-based solutions</a>, such as marsh restoration. These programs are a start in the right direction.</p>
<p>The new UN report clearly identifies key threats to species and ecosystems. Our work provides rigorous social and economic values quantifying what is at stake. My co-authors and I hope it creates new incentives to invest in coral reef conservation and restoration and to <a href="https://coastalresilience.ucsc.edu/">build coastal resilience</a>.</p><img src="https://counter.theconversation.com/content/116636/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Beck receives funding from the World Bank, German International Climate Initiative, US Department of the Interior, Kingfisher Foundation, the US Federal Emergency Management Agency and The Nature Conservancy. </span></em></p>A new report shows that coral reefs reduce damage from floods across the United States and its trust territories by more than $1.8 billion every year – and pinpoints that value state by state.Michael Beck, Research professor, University of California, Santa CruzLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1078372019-02-07T15:04:14Z2019-02-07T15:04:14ZRising seas: to keep humans safe, let nature shape the coast<figure><img src="https://images.theconversation.com/files/257489/original/file-20190206-174851-qbi2of.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Coastal erosion at Skipsea, East Yorkshire, UK.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/coastal-erosion-skipsea-east-yorkshire-361092596?src=WcILkpEckD9OnkpZ7xkM7Q-1-0">Matthew J Thomas/Shutterstock</a></span></figcaption></figure><p>Even under the most conservative climate change scenarios, sea levels 30cm higher than at present seem <a href="https://www.metoffice.gov.uk/research/collaboration/ukcp">all but certain</a> on much of the UK’s coast by the end of this century. Depending on emission scenarios, sea levels one metre higher than at present by 2100 are also plausible. </p>
<p>The knee-jerk reaction to sea level rise has traditionally been to maintain the shoreline’s position at all cost, by building new flood defence structures or upgrading old ones. <a href="https://siteresources.worldbank.org/EXTCC/Resources/EACC_FinalSynthesisReport0803_2010.pdf">More than US$10 billion per year is already spent worldwide</a> on “grey” infrastructure such as concrete walls and levies to protect against coastal flooding. Equally large are the costs incurred when coastal defences fail.</p>
<p>The United Nations has <a href="https://www.unisdr.org/we/inform/publications/52828">called on governments</a> to relocate public facilities and infrastructure from flood-prone areas, while the <a href="https://www.theccc.org.uk/publication/managing-the-coast-in-a-changing-climate/">UK Climate Change Committee</a> has urged the government to “set out how and when the hard choices that have to be made on the coast are going to happen”.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/257491/original/file-20190206-174870-13az1t6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/257491/original/file-20190206-174870-13az1t6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/257491/original/file-20190206-174870-13az1t6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/257491/original/file-20190206-174870-13az1t6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/257491/original/file-20190206-174870-13az1t6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/257491/original/file-20190206-174870-13az1t6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/257491/original/file-20190206-174870-13az1t6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">‘Grey’ sea defences cost a lot to build and maintain and the concrete they’re often made from is a source of atmospheric carbon.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sea-wall-steps-southwold-suffolk-england-184771949?src=6BPQ1lAsnT4akY47RUxXgA-1-0">Sue Chillingworth/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Letting nature decide</h2>
<p>The traditional approach of “grey” engineered sea defences locks society into ever increasing costs of replacement and maintenance. The alternatives are “<a href="https://www.gov.uk/government/news/natural-flood-management-part-of-the-nations-flood-resilience">nature-based solutions</a>” to coastal flooding and erosion, which work with natural processes to reduce flood risk and incorporate ecosystems into flood defence.</p>
<p>Rather than seeing the coast as a static line, these alternatives rethink the coastlines as zones with valuable habitats such as beaches, dunes and wetlands that act as carbon stores, places for recreation and natural buffers against the waves.</p>
<p>Schemes such as the <a href="https://www.britishwildlife.com/article/volume-26-number-6-page-382-389">Wild Coast Project</a> at Wallasea on the UK’s east coast have restored salt marshes where land had been reclaimed for agriculture years earlier. The tide and waves now regenerate salt marsh where it had been embanked and drained. If designed well, such schemes create new habitat which can <a href="https://www.cam.ac.uk/research/news/salt-marsh-plants-key-to-reducing-coastal-erosion-and-flooding">reduce the height and intensity of storm surges</a> and lower flood risk. </p>
<p>This technique for managing sea level rise can be thought of as allowing nature the space to create new coastal habitats within well-defined boundaries, akin to flooding a “sandpit”. In this sandpit, enough coastal space is vacated by humans to give natural processes room to respond to sea level rise by creating new wetlands further inland where once the terrain was dry.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/257490/original/file-20190206-174851-1n40f5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/257490/original/file-20190206-174851-1n40f5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/257490/original/file-20190206-174851-1n40f5e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/257490/original/file-20190206-174851-1n40f5e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/257490/original/file-20190206-174851-1n40f5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/257490/original/file-20190206-174851-1n40f5e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/257490/original/file-20190206-174851-1n40f5e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Coastal wetlands store carbon and act as natural buffers to storm surges.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/ocean-salt-marsh-sea-grass-dock-645099616?src=2BCSqIIGMQMOdCSnJLrkQg-1-1">JuneJ/Shutterstock</a></span>
</figcaption>
</figure>
<p>While such interventions do not enable full control over water levels and waves, they are designed to keep them at a safe distance from humans. Nature may be allowed to have some freedom to “play in the sandpit” created for it and people may not care what type of salt marsh or mudflat forms at Wallasea. But, as with “grey” infrastructure, humans ultimately build the sandpit by setting its boundaries. </p>
<p>The future of the world’s coastlines, however, is uncertain as the coast is inherently dynamic. Every wave and tide shapes the coast such that it determines how the next wave and tide can shape it. Though people may not notice it, the coast and the habitats which line it are never fixed and in fact change a great deal over a single human lifetime. People may create pockets of space for nature and think they are in control when in fact humans never were and it is doubtful they ever can be. </p>
<h2>Observing nature’s sandpit</h2>
<p>This is amply illustrated by the freshwater grazing marshes at Blakeney in Norfolk, on the UK’s east coast, where embankments were breached <a href="http://norfolkcoastnationaltrust.blogspot.com/2013/12/the-flooding-of-blakeney-freshes.html">during the 2013 storm surge</a>. A storm surge at sea forced salt water through an embankment into the Blakeney Freshes nature reserve, a unique freshwater wetland. Though unintended, salt water flooding of embanked areas like the Freshes can create a new ecosystem there and prevent flood waters from rising in adjacent areas, where people would have come to harm. </p>
<p>The Blakeney Freshes illustrate the importance of allowing sufficient space for nature to decide the boundaries of its “sandpit”. The more space given to it and the wider the buffer zone of coastal landforms, the lower the risk of flooding to areas that lie further inland. </p>
<p>As with weather forecasts, predicting how complex natural processes will interact at the coast is difficult – certainly over years and decades. It is time people stopped pretending that nature can be controlled at all, whether through “grey” or “green” engineering schemes. The best option is to watch and learn. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/257512/original/file-20190206-174894-15ipi1t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/257512/original/file-20190206-174894-15ipi1t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/257512/original/file-20190206-174894-15ipi1t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/257512/original/file-20190206-174894-15ipi1t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/257512/original/file-20190206-174894-15ipi1t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/257512/original/file-20190206-174894-15ipi1t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/257512/original/file-20190206-174894-15ipi1t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Satellite technology has made is possible to track coastal change from space.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/view-space-on-sundarbans-vast-forest-1017488386?src=7wF7EZGzyc_o-1SUQXtvPQ-1-0">Lavizzara/Shutterstock</a></span>
</figcaption>
</figure>
<p>The means for monitoring exist, with ever-improving measurement technology, data transmission and high-resolution satellite imagery, such as the <a href="https://www.copernicus.eu/en">European Commission’s Copernicus programme</a>.</p>
<p>Responding to sea level rise may be as simple as allowing space for the flow of water and sediment during extreme events. Society can do so by relinquishing the need to control the process and <a href="https://www.theguardian.com/environment/2018/nov/28/coastal-flooding-and-peat-bogs">restricting development near the coast</a>, creating areas that nature can “claim” with whatever habitat it wishes to “build” there.</p>
<p>As a salt marsh turns into a tidal flat, a freshwater field into a salty lagoon, there is the opportunity to stand back, watch and learn to better understand how and why those changes happen and how people can benefit from change rather than fight a losing battle to prevent it.</p><img src="https://counter.theconversation.com/content/107837/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Iris Möller has received research project funding under the 7th Framework Programme of the European Union and the European Community's Horizon 2020 Research and Innovation Programme as well as the Natural Environment Research Council. She does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond her academic appointment.</span></em></p>Rising sea levels won’t be solved by trying to fix the coast in place. For a defence from coastal flooding, we need to step back.Iris Möller, Lecturer in Coastal Processes, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1046702018-10-11T10:39:58Z2018-10-11T10:39:58ZProtecting wetlands helps communities reduce damage from hurricanes and storms<figure><img src="https://images.theconversation.com/files/239935/original/file-20181009-72133-1o1hr7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Protecting coastal wetlands, like this slough in Florida's Everglades National Park, is a cost-effective way to reduce flooding and storm damage.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/27WDLZV">NPS/C. Rivas</a></span></figcaption></figure><p>2017 was the worst year on record for hurricane damage in Texas, Florida and the Caribbean from <a href="https://www.nhc.noaa.gov/data/tcr/AL092017_Harvey.pdf">Harvey</a>, <a href="https://www.nhc.noaa.gov/data/tcr/AL112017_Irma.pdf">Irma</a> and <a href="https://www.nhc.noaa.gov/data/tcr/AL152017_Maria.pdf">Maria</a>. We had hoped for a reprieve this year, but less than a month after Hurricane Florence devastated communities across the Carolinas, Hurricane Michael has struck Florida.</p>
<p>Coastlines are being developed rapidly and intensely in the United States and worldwide. The population of central and south Florida, for example, has grown by <a href="https://www.nytimes.com/2017/09/07/climate/florida-hurricane-irma-damage.html?mcubz=0">6 million since 1990</a>. Many of these cities and towns face the brunt of damage from hurricanes. In addition, rapid coastal development is destroying natural ecosystems like marshes, mangroves, oyster reefs and coral reefs – resources that help protect us from catastrophes. </p>
<p>In a unique partnership <a href="https://www.lloyds.com/lloyds/corporate-responsibility/charity/tercentenary-research-foundation/role-of-coastal-habitats-in-managing-natural-hazards">funded by Lloyd’s of London</a>, we worked with colleagues in academia, environmental organizations and the insurance industry to calculate the financial benefits that coastal wetlands provide by reducing storm surge damages from hurricanes. Our <a href="http://dx.doi.org/10.1038/s41598-017-09269-z">study</a>, published in 2017, found that this function is enormously valuable to local communities. It offers new evidence that protecting natural ecosystems is an effective way to reduce risks from coastal storms and flooding.</p>
<figure>
<iframe src="https://player.vimeo.com/video/188757883" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Coastal wetlands and flood damage reduction: A collaboration between academia, conservation and the risk industry.</span></figcaption>
</figure>
<h2>The economic value of flood protection from wetlands</h2>
<p>Although there is broad understanding that <a href="https://doi.org/10.1371/journal.pone.0154735">wetlands can protect coastlines</a>, researchers have not explicitly measured how and where these benefits translate into dollar values in terms of reduced risks to people and property. To answer this question, our group worked with experts who understand risk best: insurers and risk modelers. </p>
<p>Using the industry’s storm surge <a href="http://www.rms.com/models/flood">models</a>, we compared the flooding and property damages that occurred with wetlands present during Hurricane Sandy to the damages that would have occurred if these wetlands were lost. First we compared the extent and severity of flooding during Sandy to the flooding that would have happened in a scenario where all coastal wetlands were lost. Then, using high-resolution data on assets in the flooded locations, we measured the property damages for both simulations. The difference in damages – with wetlands and without – gave us an estimate of damages avoided due to the presence of these ecosystems.</p>
<p><a href="http://dx.doi.org/10.1038/s41598-017-09269-z">Our paper</a> shows that during Hurricane Sandy in 2012, coastal wetlands prevented more than US$625 million in direct property damages by buffering coasts against its storm surge. Across 12 coastal states from Maine to North Carolina, wetlands and marshes reduced damages by an average of 11 percent. </p>
<p>These benefits varied widely by location at the local and state level. In Maryland, wetlands reduced damages by 30 percent. In highly urban areas like New York and New Jersey, they provided hundreds of millions of dollars in flood protection.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/186483/original/file-20170918-30563-celbpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/186483/original/file-20170918-30563-celbpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186483/original/file-20170918-30563-celbpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=763&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186483/original/file-20170918-30563-celbpm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=763&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186483/original/file-20170918-30563-celbpm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=763&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186483/original/file-20170918-30563-celbpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=959&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186483/original/file-20170918-30563-celbpm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=959&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186483/original/file-20170918-30563-celbpm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=959&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wetland benefits for flood damage reduction during Sandy (redder areas benefited more from having wetlands).</span>
<span class="attribution"><a class="source" href="https://www.nature.com/articles/s41598-017-09269-z/figures/1">Narayan et al., Nature Scientific Reports 7, 9463 (2017).</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Wetlands reduced damages in most locations, but not everywhere. In some parts of North Carolina and the Chesapeake Bay, wetlands redirected the surge in ways that protected properties directly behind them, but caused greater flooding to other properties, mainly in front of the marshes. Just as we would not build in front of a seawall or a levee, it is important to be aware of the impacts of building near wetlands.</p>
<p>Wetlands reduce flood losses from storms every year, not just during single catastrophic events. We examined the effects of marshes across 2,000 storms in Barnegat Bay, New Jersey. These marshes reduced flood losses annually by an average of 16 percent, and up to 70 percent in some locations.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/186485/original/file-20170918-30536-5x4eea.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/186485/original/file-20170918-30536-5x4eea.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186485/original/file-20170918-30536-5x4eea.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=261&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186485/original/file-20170918-30536-5x4eea.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=261&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186485/original/file-20170918-30536-5x4eea.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=261&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186485/original/file-20170918-30536-5x4eea.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=328&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186485/original/file-20170918-30536-5x4eea.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=328&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186485/original/file-20170918-30536-5x4eea.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=328&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Reductions in annual flood losses to properties that have a marsh in front (blue) versus properties that have lost the marshes in front (orange).</span>
<span class="attribution"><a class="source" href="https://www.nature.com/articles/s41598-017-09269-z/figures/3">Narayan et al., Nature Scientific Reports 7, 9463 (2017).</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In related research, our team has also shown that coastal ecosystems can be highly cost-effective for risk reduction and adaptation <a href="https://doi.org/10.1371/journal.pone.0192132">along the U.S. Gulf Coast</a>, particularly as part of a portfolio of green (natural) and gray (engineered) solutions.</p>
<h2>Reducing risk through conservation</h2>
<p>Our research shows that we can measure the reduction in flood risks that coastal ecosystems provide. This is a central concern for the <a href="https://hbr.org/2017/08/how-the-insurance-industry-can-push-us-to-prepare-for-climate-change">risk and insurance industry</a> and for coastal managers. We have shown that these risk reduction benefits are significant, and that there is a strong case for conserving and protecting our coastal ecosystems. </p>
<p>The next step is to <a href="http://nature.org/FinancingNaturalInfrastructureReport10.7291/V9PN93H3">use these benefits to create incentives</a> for wetland conservation and restoration. Homeowners and municipalities could receive reductions on insurance premiums for managing wetlands. Post-storm spending should include more <a href="http://news.maryland.gov/dnr/2017/09/20/new-grant-program-funds-nature-based-solutions-to-protect-coastal-communities/">support for this natural infrastructure</a>. And new financial tools such as <a href="http://www.refocuspartners.com/rebound/">resilience bonds</a>, which provide incentives for investing in measures that reduce risk, could support wetland restoration efforts too.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/187408/original/file-20170925-18946-e7hsee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/187408/original/file-20170925-18946-e7hsee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/187408/original/file-20170925-18946-e7hsee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/187408/original/file-20170925-18946-e7hsee.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/187408/original/file-20170925-18946-e7hsee.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/187408/original/file-20170925-18946-e7hsee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/187408/original/file-20170925-18946-e7hsee.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/187408/original/file-20170925-18946-e7hsee.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The dense vegetation and shallow waters within wetlands can slow the advance of storm surge and dissipate wave energy.</span>
<span class="attribution"><a class="source" href="http://www.nad.usace.army.mil/Portals/40/siteimages/NACCS/20.jpg">USACE</a></span>
</figcaption>
</figure>
<h2>Improving long-term resilience</h2>
<p>Increasingly, communities are also beginning to consider ways to <a href="https://theconversation.com/6-rules-for-rebuilding-infrastructure-in-an-era-of-unprecedented-weather-events-83129">improve long-term resilience</a> as they assess their recovery options.</p>
<p>There is often a strong desire to return to the status quo after a disaster. More often than not, this means <a href="https://doi.org/10.15351/2373-8456.1069">rebuilding seawalls</a> and <a href="https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/150065">concrete barriers</a>. But these structures are expensive, will need constant upgrades as as sea levels rise, and can damage coastal ecosystems. </p>
<p>Even after suffering years of damage, Florida’s <a href="https://doi.org/10.1016/j.ecss.2012.02.021">mangrove wetlands</a> and <a href="https://www.nature.com/articles/s41467-018-04568-z">coral reefs</a> play crucial roles in protecting the state from hurricane surges and waves. And yet, over the last six decades urban development has <a href="https://sanctuaries.noaa.gov/science/condition/fknms/state.html">eliminated</a> half of Florida’s historic mangrove habitat. Losses are still occurring across the state from the Keys to <a href="http://reefrelieffounders.com/mangroves.html">Tampa Bay and Miami</a>. </p>
<p>Protecting and nurturing these natural first lines of defense could help Florida homeowners reduce property damage during future storms. In the past two years our team has worked with the private sector and government agencies to help translate these risk reduction benefits into action for rebuilding natural defenses.</p>
<p>Across the United States, the Caribbean and Southeast Asia, coastal communities face a crucial question: Can they <a href="https://theconversation.com/what-victims-of-hurricane-harvey-can-learn-from-katrina-as-rebuilding-begins-83184">rebuild</a> in ways that make them better prepared for the next storm, while also conserving the natural resources that make these locations so valuable? Our work shows that the answer is yes. </p>
<p><em>This is an updated version of an <a href="https://theconversation.com/as-communities-rebuild-after-hurricanes-study-shows-wetlands-can-significantly-reduce-property-damage-83935">article</a> originally published on Sept. 25, 2017.</em></p><img src="https://counter.theconversation.com/content/104670/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Siddharth Narayan received funding from the Lloyd's Tercentenary Research Foundation and the Science for Nature and People Partnership for this work. </span></em></p><p class="fine-print"><em><span>Michael Beck has received funding from the Lloyd's Tercentenary Research Foundation. He is a Research Professor at UC Santa Cruz and Lead Marine Scientist for The Nature Conservancy.</span></em></p>Coastal development is destroying marshes, mangroves and other wetlands that provide valuable protection from hurricanes and storms. Research shows these benefits can be worth millions of dollars.Siddharth Narayan, Postdoctoral Fellow, Coastal Flood Risk, University of California, Santa CruzMichael Beck, Research professor, University of California, Santa CruzLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1031202018-09-14T14:32:21Z2018-09-14T14:32:21ZBarrier islands are natural coast guards that absorb impacts from hurricanes and storms<figure><img src="https://images.theconversation.com/files/239967/original/file-20181009-72100-gh60vh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cumberland Island National Seashore off the coast of Georgia.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/jUyrVw">NPS</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>When storms like <a href="https://www.nytimes.com/2022/09/29/us/hurricane-ian-florida-damage.html">Hurricane Ian</a> make landfall, the first things they hit often are <a href="https://web.archive.org/web/20100808200102/http:/www.csc.noaa.gov:80/beachnourishment/html/geo/barrier.htm">barrier islands</a> – thin ribbons of sand that line the U.S. Atlantic and Gulf coasts. It’s hard to imagine how these narrow strips can withstand such forces, but in fact, many of them have buffered our shores for centuries. </p>
<p>Barrier islands protect <a href="http://www.jcronline.org/doi/abs/10.2112/09-1190.1">about 10 percent of coastlines worldwide</a>. When hurricanes and storms make landfall, these strands absorb much of their force, reducing wave energy and protecting inland areas. </p>
<p>They also provide a sheltered environment that enables estuaries and marshes to form behind them. These zones serve many valuable ecological functions, such as <a href="https://doi.org/10.1890/10-1510.1">reducing coastal erosion, purifying water and providing habitat for fish and birds</a>. </p>
<p>Many barrier islands have been developed into popular tourist destinations, including Florida’s <a href="https://www.washingtonpost.com/nation/2022/10/02/hurricane-ian-sanibel/">Sanibel Island</a> and South Carolina’s <a href="https://wpde.com/news/local/pawleys-island-hit-hard-by-hurricane-ian-now-works-hard-to-clean-up">Pawleys Island</a>, both of which suffered heavy damage from Hurricane Ian. Islands that have been preserved in their natural state can move with storms, shifting their shapes over time. But many human activities interfere with these natural movements, making the islands more vulnerable. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/236308/original/file-20180913-177941-1ffd7ss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/236308/original/file-20180913-177941-1ffd7ss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/236308/original/file-20180913-177941-1ffd7ss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/236308/original/file-20180913-177941-1ffd7ss.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/236308/original/file-20180913-177941-1ffd7ss.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/236308/original/file-20180913-177941-1ffd7ss.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/236308/original/file-20180913-177941-1ffd7ss.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/236308/original/file-20180913-177941-1ffd7ss.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ocean City, Maryland is built on Fenwick Island, an Atlantic barrier island.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Ocean_City_Maryland_aerial_view_north.jpg">USACE</a></span>
</figcaption>
</figure>
<h2>Islands on the move</h2>
<p>Barrier islands are made of sandy, erodible soil and subject to high-energy wave action. They are dynamic systems that <a href="https://pubs.usgs.gov/of/2007/1161/OFR-2007-1161-screen.pdf">constantly form and reform</a>. But this doesn’t necessarily mean the islands are disappearing. Rather, they migrate naturally, building up sand in some areas and eroding in other areas. </p>
<p>New islands can form out in the ocean, either because local sea level drops or tectonics or sediment deposition raises the ocean floor. Or they may shift laterally along the shore as currents carry sediments from one end of the island toward the other. On the East Coast, barrier islands usually move from north to south because longshore currents transport sand in the same direction. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/236306/original/file-20180913-177941-1qg056t.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/236306/original/file-20180913-177941-1qg056t.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/236306/original/file-20180913-177941-1qg056t.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=925&fit=crop&dpr=1 600w, https://images.theconversation.com/files/236306/original/file-20180913-177941-1qg056t.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=925&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/236306/original/file-20180913-177941-1qg056t.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=925&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/236306/original/file-20180913-177941-1qg056t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1162&fit=crop&dpr=1 754w, https://images.theconversation.com/files/236306/original/file-20180913-177941-1qg056t.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1162&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/236306/original/file-20180913-177941-1qg056t.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1162&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How longshore drift moves sediment along a beach.
1=beach.
2=sea
3=longshore current direction
4=incoming waves
5=swash
6=backwash</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Longshore_drift#/media/File:Longshore_i18n.png">USGS</a></span>
</figcaption>
</figure>
<p>And over time many barrier islands move landward, toward the shore. This typically happens because local sea levels rise, so waves wash over the islands during storms, moving sand from the ocean side to the inland side.</p>
<h2>Building on shifting sands</h2>
<p>Building hard infrastructure such as homes, roads and hotels on barrier islands interrupts their lateral migration. Needless to say, beach communities want their dunes to stay in place, so the response often is to build control structures, such as <a href="http://www.beachapedia.org/Shoreline_Structures_">seawalls and jetties</a>.</p>
<p>This protects buildings and roads, but it also disrupts natural sand transportation. Blocking erosion up-current means that no sediments are transported down-current, leaving those areas starved of sediment and vulnerable to erosion.</p>
<p>Many sandy tourist beach towns along the East Coast also turn to <a href="https://coast.noaa.gov/digitalcoast/tools/beach-nourishment.html">beach nourishment</a> – pumping tons of sand from offshore – to replace sand lost through erosion. This does not interrupt natural sand transportation, but it is a very expensive and temporary fix. </p>
<p>For example, since the 1940s Florida has spent over US$1.3 billion on beach nourishment projects, and North Carolina has spent <a href="https://www.reuters.com/article/us-florida-storm-beaches/gone-with-the-wind-storms-deepen-floridas-beach-sand-crunch-idUSKCN1G00W4">more than $700 million</a>. This added sand will eventually wash away, quite possibly during the next hurricane to hit the coast, and have to be replaced.</p>
<h2>What kind of protection?</h2>
<p>In some cases, however, leaving barrier islands to do their own natural thing can cause problems for people. Some cities and towns, such as Miami and Biloxi, are located behind barrier islands and rely on them as a first line of defense against storms. </p>
<p>And many communities depend on natural resources provided by the estuaries and wetlands behind barrier islands. For example, Pamlico Sound – the protected waters behind North Carolina’s Outer Banks – is a <a href="https://ncseagrant.ncsu.edu/coastwatch/previous-issues/2012-2/summer-2012/the-pamlico-sound-fishing-gem-of-north-carolina/">rich habitat</a> for blue crabs and popular sport fish such as red drum.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/239955/original/file-20181009-72124-1p4wgyn.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/239955/original/file-20181009-72124-1p4wgyn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/239955/original/file-20181009-72124-1p4wgyn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/239955/original/file-20181009-72124-1p4wgyn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/239955/original/file-20181009-72124-1p4wgyn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/239955/original/file-20181009-72124-1p4wgyn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=402&fit=crop&dpr=1 754w, https://images.theconversation.com/files/239955/original/file-20181009-72124-1p4wgyn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=402&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/239955/original/file-20181009-72124-1p4wgyn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=402&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Survey images of barrier islands of Alabama, Mississippi and southeast Louisiana, collected to document changes resulting from Hurricane Isaac in August 2012.</span>
<span class="attribution"><a class="source" href="https://pubs.usgs.gov/ds/0839/ds839title.html">USGS</a></span>
</figcaption>
</figure>
<p>Unmanaged, some of these islands may not move the way we want them to. For example, a storm breach on a barrier island that protects a city would make that city more vulnerable. </p>
<p>Here in Mississippi, a string of <a href="https://www.britannica.com/place/Gulf-Islands-National-Seashore">uninhabited barrier islands</a> off our coast separates Mississippi Sound from the Gulf of Mexico. Behind the islands is a productive estuary, important wetlands and cities such as Biloxi and Gulfport. </p>
<p>Because the Mississippi River has been dredged and enclosed between levees to keep it from spilling over its banks, this area does not receive the sediment loads that the river once deposited in this part of the Gulf. As a result, the islands are eroding and disappearing. </p>
<p>To slow this process, state and federal agencies have <a href="https://www.nps.gov/guis/learn/nature/mscip.htm">artificially nourished the islands</a> to keep them in place and preserve the cities, livelihoods and ecological habitats behind them. This project <a href="https://fh-sites.imgix.net/sites/1698/2019/02/18223531/Camille-Cut-is-no-more.pdf">filled a major breach</a> cut in one island by Hurricane Camille in 1969, making the island a more effective storm buffer for the state’s coast. </p>
<h2>When to retreat?</h2>
<p>Geologically, barrier islands are not designed to stay in one place. But development on them is intended to last, although critics argue that climate change and sea level rise will inevitably <a href="https://theconversation.com/far-sighted-adaptation-to-rising-seas-is-blocked-by-just-fixing-eroded-beaches-96503">force a retreat from the shore</a>.</p>
<p>Reconciling humans’ love of the ocean with the hard realities of earth science is not easy. People will always be drawn to the coast, and prohibiting development is politically impractical. However, there are some ways to help conserve barrier islands while maintaining areas for tourism activities.</p>
<p>First, federal, state and local laws can reduce incentives to build on barrier islands by putting the burden of rebuilding after storms on owners, not on the government. Many critics argue that the <a href="https://theconversation.com/what-is-flood-insurance-and-why-the-system-is-broken-6-questions-answered-103058">National Flood Insurance Program</a> has encouraged homeowners to rebuild on <a href="https://www.nytimes.com/2012/11/19/science/earth/as-coasts-rebuild-and-us-pays-again-critics-stop-to-ask-why.html?pagewanted=all">barrier islands</a> and other coastal locations, even after suffering repeated losses in many storms.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/487839/original/file-20221003-12-zabo4g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial view of a causeway with water and sediment flowing through a gap in the center" src="https://images.theconversation.com/files/487839/original/file-20221003-12-zabo4g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487839/original/file-20221003-12-zabo4g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487839/original/file-20221003-12-zabo4g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487839/original/file-20221003-12-zabo4g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487839/original/file-20221003-12-zabo4g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487839/original/file-20221003-12-zabo4g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487839/original/file-20221003-12-zabo4g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hurricane Ian breached the causeway connecting Sanibel Island, Florida to the mainland, forcing residents to leave by boat after the storm passed. Image taken Sept. 30, 2022.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/an-aerial-picture-taken-on-september-30-2022-shows-the-news-photo/1243627942">Ricardo Arduengo/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>Second, construction on barrier islands should leave dunes and vegetation undisturbed. This helps to keep their sand transportation systems intact. When roads and homes directly adjacent to beaches are damaged by storms, owners should be required to move back from the shoreline in order to provide a natural buffer between any new construction and the coastline.</p>
<p>Third, designating more conservation areas on barrier islands will maintain some of the natural sediment transportation and barrier island migration processes. And these conservation areas are popular nature-based tourism attractions. Protected barrier islands such as <a href="https://www.nps.gov/asis/index.htm">Assateague</a>, <a href="https://www.nps.gov/pais/index.htm">Padre</a> and the <a href="https://www.nps.gov/caco/index.htm">Cape Cod National Seashore</a> are popular destinations in the U.S. national park system.</p>
<p>Finally, development on barrier islands should be done with change in mind and a preference for temporary or movable infrastructure. The islands themselves are surprisingly adaptable, but whatever is built in these dynamic settings is likely sooner or later to be washed away.</p><img src="https://counter.theconversation.com/content/103120/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anna Linhoss receives funding from NOAA and the Mississippi Department of Marine Resources. </span></em></p>How do the narrow ribbons of sand that line the Atlantic and Gulf coasts withstand the force of hurricanes? The answer lies in their shape-shifting abilities.Anna Linhoss, Associate Professor of Engineering, Auburn UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/965032018-08-27T10:46:46Z2018-08-27T10:46:46ZFar-sighted adaptation to rising seas is blocked by just fixing eroded beaches<figure><img src="https://images.theconversation.com/files/232530/original/file-20180817-165937-hbppl1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Beach erosion in Nags Head, North Carolina, photographed May 15, 2005.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/8Kw1EN">Soil Science</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Coastal communities around the world are struggling to adapt to rising sea levels and increasingly severe coastal storms. In the United States, local governments are making investments to reduce those risks, such as protecting shorelines with seawalls, “nourishing” eroded beaches by adding sand and rerouting or redesigning roads and bridges. </p>
<p>In the short run, spending public money this way is economically rational. But in the long run, many people who live near coastlines will probably have to relocate as seas <a href="https://blogs.ei.columbia.edu/2018/04/24/climate-impacts-coastlines-rising-tides-increasing-risks/">continue to rise</a>. </p>
<p>We have studied this problem by combining insights from our work in <a href="https://www.coastalstudiesinstitute.org/about/faculty-and-staff/andy-keeler/">economics</a>, <a href="https://link.springer.com/chapter/10.1007/978-3-319-68086-6_12">coastal geomorphology</a> and <a href="https://scholar.google.com/citations?user=sWGqncEAAAAJ&hl=en">engineering</a>. As we have <a href="https://doi.org/10.1002/2018EF000828">explained elsewhere</a>, short-term actions to adapt to coastal flooding can actually increase risks to lives and property. By raising the value of coastal properties, these steps encourage people to stay in place and delay decisions about more drastic solutions, such as moving inland. </p>
<h2>Keeping millions in harm’s way</h2>
<p>According to recent estimates, a 1-foot increase in sea levels will put <a href="https://doi.org/10.1038/nclimate2961">about 1 million people in the United States at risk</a>, and 3 feet will threaten about 4 million people. Global sea levels currently are <a href="https://science2017.globalchange.gov/chapter/12/">projected to rise</a> 0.5 to 2.1 feet by 2050 and 1.0 to 8.2 feet by 2100.</p>
<p>As we see it, market forces and public risk reduction policies interact in unexpected ways, reducing incentives for communities to make long-term plans for retreating from the shore. Nourishing beaches and building seawalls signal to individuals and businesses that their risks are lower. This makes them more likely to build long-lasting structures in risky areas and renovate and maintain existing structures. As a result, their property values increase, which reinforces economic and political arguments for more risk-reduction engineering. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/232524/original/file-20180817-165949-1eb2lib.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/232524/original/file-20180817-165949-1eb2lib.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/232524/original/file-20180817-165949-1eb2lib.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=382&fit=crop&dpr=1 600w, https://images.theconversation.com/files/232524/original/file-20180817-165949-1eb2lib.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=382&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/232524/original/file-20180817-165949-1eb2lib.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=382&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/232524/original/file-20180817-165949-1eb2lib.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=480&fit=crop&dpr=1 754w, https://images.theconversation.com/files/232524/original/file-20180817-165949-1eb2lib.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=480&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/232524/original/file-20180817-165949-1eb2lib.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=480&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wind pushes water over Highway 64 as Hurricane Arthur passes through Nags Head, North Carolina, July 4, 2014.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Storm-Shortage/e1c4ef8296294189a5d4195b4b2561f2/10/0">AP Photo/Gerry Broome, File</a></span>
</figcaption>
</figure>
<p>To illustrate this pattern, we compared a sample of houses in Nags Head and Kitty Hawk, North Carolina, two popular beach towns less than 10 miles apart on North Carolina’s Outer Banks. When we consulted county tax appraisal values, Nags Head beaches had routinely received sand from beach nourishment, whereas Kitty Hawk beaches had not. On average, homes in our Nags Head sample were worth over US$1 million, while homes in the Kitty Hawk sample were worth about $200,000. </p>
<p>Other researchers have found that in some locations, the threat of rising seas is <a href="https://www.washingtonpost.com/national/health-science/sea-level-rise-is-eroding-home-value-and-owners-might-not-even-know-it/2018/08/20/ff63fa8c-a0d5-11e8-93e3-24d1703d2a7a_story.html?utm_term=.faefacaed95e">eroding coastal property values</a>. But this tends to be true for properties that are viewed as highly vulnerable – for example, homes that have already flooded. In contrast, homes that are elevated or have other flood-proofing features tend to have much higher values, so they are perceived as assets.</p>
<h2>Subsidizing risky choices</h2>
<p>Some amount of risk reduction makes sense. If people who benefited paid its full cost, and everyone involved understood how imminent the risk was and how much engineering solutions would cost, then market forces would likely produce reasonably efficient solutions. </p>
<p>As an example, flood-prone Norfolk, Virginia recently <a href="https://www.npr.org/2018/03/01/589634980/norfolk-requires-developers-to-do-more-against-flooding">adopted an ordinance</a> requiring almost all new homes and many major renovations to be elevated and include other flood-proofing features. This approach will help to price flood protection into the cost of homes and will tend to reduce demands to directly subsidize protective engineering, flood insurance and post-disaster assistance. </p>
<p>In our view, such solutions are a move in the right direction. But they will not break the positive feedback loop we describe as long as other public policies continue to skew perceptions of the long-term viability of coastal communities. </p>
<p>Engineering projects to slow shoreline retreat and reduce flooding generally receive <a href="https://doi.org/10.1371/journal.pone.0121278">smaller subsidies now than in past decades</a>, but many communities still benefit. For example, beach nourishment in Ocean City, Maryland is cost-shared between the federal government, which pays about half, and <a href="https://oceancitymd.gov/oc/departments/engineering/beach-replenishment/">state and local agencies</a>. The Federal Emergency Management Agency helps pay to <a href="https://www.fema.gov/sandy-5-year">rebuild homes and public buildings damaged in major disasters</a>. And allowing people to deduct local taxes on their federal tax forms partly subsidizes local tax financing for risk reduction.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/PQi0hsH9nEQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Beach nourishment started at New York’s Coney Island a century ago. But with the sheer volume of sand needed to keep up with sea level rise, its costs could outweigh its benefits within a few decades.</span></figcaption>
</figure>
<h2>Inaccurate perceptions of risk</h2>
<p>Information and uncertainty are larger problems. Many coastal residents <a href="https://theconversation.com/after-harvey-many-texans-will-think-differently-about-hurricane-risks-83262">do not perceive medium- and long-term climate risk</a> to be as serious as the scientific consensus suggests. Moreover, scientists are still analyzing how fast sea levels are likely to rise. Future storm frequency is uncertain, and could be affected by changes in global greenhouse gas emission trends. </p>
<p>On the positive side, engineering innovations such as <a href="https://theconversation.com/build-disaster-proof-homes-before-storms-strike-not-afterward-61947">designing storm-resistant homes</a> could become more effective. But existing approaches like beach nourishment are likely to become more expensive as <a href="https://theconversation.com/the-world-is-facing-a-global-sand-crisis-83557">sand resources diminish</a> and more communities compete for them. And growing uncertainty is likely to increase near-term demand for risk reduction engineering.</p>
<p>The most critical time for adaptation decisions is immediately after a storm or flood. Faced with expensive repairs or rebuilding, property owners face higher costs to return to the status quo. But if homeowners expect that public resources will be spent to protect them against future disasters, they are less likely to consider making big changes. </p>
<p>Federal or state financial rebuilding assistance creates a similar bias. If that money were used to subsidize relocation or other drastic adaptive actions, rebuilding patterns would be different. So far, however, programs for <a href="https://www.fema.gov/faq-details/Buy-out-of-flooded-property-1370032125293">buying out flood-damaged properties</a> have been largely unsuccessful. Many factors, including residents’ level of experience with disaster recovery and financial concerns, can make people <a href="https://doi.org/10.1016/j.ijdrr.2015.06.008">unwilling to consider relocating</a>.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/BkfmwuRF6g9/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Incentives to think long-term</h2>
<p>There is no perfect formula for balancing near-term climate-proofing against more drastic steps to move people away from the coasts. But we believe that when communities focus excessively on reducing near-term threats, they risk inhibiting the successful adaptation that they are trying to promote.</p>
<p>We have three suggestions for breaking this cycle. First, local land use policies could be designed to discourage rebuilding homes to similar or higher property values after damage from storms. Second, communities could put increasing emphasis on adaptive engineering and large-scale planning practices – for example, sunsetting beach nourishment projects when sea level rise reaches some preannounced level. </p>
<p>Finally, adaptation decisions could be planned and implemented at a multi-jurisdictional level, rather than town by town. This approach would help to avoid “rich towns get richer” dynamics that can develop when wealthier jurisdictions deploy sand resources and other protective measures in a way that reduces their own risk while ignoring or heightening threats to nearby locations.</p>
<p>Change is coming to coasts around the world. We believe that broader understanding of how markets and public policy interact is essential to minimize the social and economic costs of this change.</p><img src="https://counter.theconversation.com/content/96503/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew G Keeler receives funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Dylan McNamara has received funding from the National Science Foundation, the Gordon and Betty Moore Foundation, the National Oceanic and Atmospheric Administration, and the North Carolina Sea Grant. </span></em></p><p class="fine-print"><em><span>Jennifer Irish receives or has received funding from the National Science Foundation, National Oceanic and Atmospheric Administration’s Sea Grant, U.S. Army Corps of Engineers, U.S. Department of Energy, U.S. Nuclear Regulatory Commission, National Commission on Energy Policy, South Atlantic Landscape Conservation Cooperative, State of Texas Department of Public Safety, and Texas General Land Office. She is a Diplomate of Coastal Engineering and licensed Professional Engineer in New York and in Virginia. She is or has recently been affiliated with the American Society of Civil Engineers, American Geophysical Union, American Shore and Beach Preservation Association, PIANC, and Engineers Without Borders.</span></em></p>Many US coastal towns are building defenses to protect against rising seas and storms. This can encourage people to stay in place when they should be moving inland.Andrew G. Keeler, Professor of Economics and Program Head, Public Policy and Coastal Sustainability, UNC Coastal Studies Institute, East Carolina UniversityDylan McNamara, Professor of Physics and Physical Oceanography, University of North Carolina WilmingtonJennifer Irish, Professor of Civil and Environmental Engineering, Virginia TechLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/752872017-03-29T02:13:29Z2017-03-29T02:13:29ZCyclone Debbie: we can design cities to withstand these natural disasters<p>What happens after <a href="https://theconversation.com/tracking-the-storm-the-science-behind-tropical-cyclone-debbie-75300">Cyclone Debbie</a> is a familiar process. It has been repeated many times in cities around the world. The reason is that our cities are not designed for these types of events.</p>
<p>So we know what comes next. Queenslanders affected by Debbie will complain about the damage, the costs and the need for insurers to act now to compensate their losses. The state and federal governments will extensively discuss who is to blame. </p>
<p>The shambles will be cleared and life will eventually get back to normal. Billions of dollars will be spent on relocating people and on repairing the damage and public works. A state-level levy may even be necessary to pay for all the extra costs. Two storms, Katrina and Sandy, cost the United States <a href="https://cityroom.blogs.nytimes.com/2012/11/27/hurricane-sandy-vs-hurricane-katrina/">more than US$200 billion</a> between them. </p>
<p>Yet we know what cyclones do. They bring, for a relatively short time, huge gusty winds. These are inconvenient but have proven not too damaging. </p>
<p>The greatest risk comes from storm surge and rainfall. Both bring a huge amount of water. And all this water has to find a way to get out of our living environment. </p>
<p>Despite knowing, approximately, where cyclones tend to occur, we never thought about adjusting our cities to their effects. It would make a huge financial difference if we did. </p>
<p>So, what can we do to build our cities differently to ensure the impacts of cyclones – and the accompanying rainfall and storm surges – do not disrupt urban life? The answer to all of this is design. </p>
<p>The usual design of current cities and towns brought us problems in the first place. We need to fundamentally rethink the design of our built-up areas.</p>
<h2>Rethinking coastal and urban design</h2>
<p>It starts with coastal design. We are used to building dams and coastal protection <a href="http://www.abcb.gov.au/-/media/Files/Resources/.../Handbook-Flood-2012.pdf">against storm surges happening once in 100 years</a>. For comparison, the protection standards in the low-lying Netherlands are designed to protect the country against a once-in-10,000-years flood. But nature has proven to be stronger than our artificial constructs can handle.</p>
<p>An alternative design approach is to rely on the natural coastal processes of land forming – such as reefs, islands, mangroves, beaches and dunes. Humans can help the formation of these natural protectors by providing the triggers for them to emerge. </p>
<p>As an example, when we put sand in front of the coast, the currents and waves will transport the sand towards the coast and build up new and larger beaches. This example is realised in front of the Dutch coast and is known as the <a href="http://www.dezandmotor.nl/en/">sand engine</a>. But nature will build them up to form a much stronger system than humans ever could. </p>
<p>Instead of coasts, beaches and real estate being washed away, new land and larger beaches may be formed as a result of these processes. This requires design thinking, insights into the resilience of the coastal system, and understanding of the natural forces at play.</p>
<p>Second, urban design should reconsider the way we build our cities. Most urban areas do not have the capacity to “welcome” lots of water. And it is about lots of water, not the average shower or two. </p>
<p>Until cyclones are gone, these enormous amounts of water need to be stored for a short period in dense urban areas. This goes beyond <a href="https://www.environment.gov.au/system/files/resources/1873905a-f5b7-4e3c-8f45-0259a32a94b1/files/wsud-guidelines.pdf">water-sensitive urban design</a>.</p>
<p>Despite the benefits of water-sensitive design in many urban developments, when the going gets tough, this is just not enough. Water-sensitive urban design can barely cope with average rainfall peaks. So, in times of severe weather events, cities need to have additional spaces to store all this water.</p>
<p>The general rule here is to store every raindrop as long as possible where it falls.</p>
<h2>How and where should we redesign our cities?</h2>
<p>So, what can be done to cyclone-proof our cities? We can:</p>
<ul>
<li><p>Create larger green spaces, which are connected in a natural grid, increase the capacity of these green systems by adding eco-zones and wetlands, and redesign river and creek edges. Remove the concrete basins from every creek in the city.</p></li>
<li><p>Use large public spaces, such as parking spaces near shopping centres, ovals and football pitches, for temporarily capturing and storing excess rainwater. Small adjustments at the edges of these places are generally enough to capture the water.</p></li>
<li><p>Turn parking garages into temporary storage basins.</p></li>
<li><p>Redesign street profiles and introduce green and water-zones in streets. Out of every three-lane street, one lane can be transformed into a green lane, which can absorb rainwater. </p></li>
<li><p>Redesign all impervious, sealed spaces and turn these into areas where the water can infiltrate the soil. Use permeable materials.</p></li>
<li><p>Think in an integrated way about street infrastructure, green and ecological systems, and the water system.</p></li>
</ul>
<p>These design interventions are not new and have been done abroad in cities such as Rotterdam, Hamburg or Stockholm. If we could add to these the redesign of roofs and gardens of industrial and residential estates and turn these into green roofs and rain gardens, the city would start to operate as a huge sponge. </p>
<p>When it rains, the city absorbs the huge amounts of water and releases it slowly to the creek and river system after the rain has gone. This way, green spaces and water spaces not only play an important role during and just after a cyclone, but they then add quality to people’s immediate living environment. </p>
<p>And maybe the best of all this: the bill Debbie and other natural disasters would present to government, industries and insurers could be much lower.</p><img src="https://counter.theconversation.com/content/75287/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rob Roggema does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Cities would suffer much less damage and avoid the huge financial losses if we designed them to cope with the effects of cyclones.Rob Roggema, Professor of Sustainable Urban Environments, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/728352017-03-06T11:27:17Z2017-03-06T11:27:17ZHow Europe’s coastal cities can cope with rising sea levels<figure><img src="https://images.theconversation.com/files/159312/original/image-20170303-29046-f1okui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/vic_206/12938274904/sizes/l">vic_206/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>The average global sea level has risen by more than 20cm since 1980 – that’s a rate of 0.5mm per month – according to <a href="http://journal.frontiersin.org/article/10.3389/fmars.2016.00265/full">new research</a> from the Basque Centre for Climate Change (BCCC). These are frightening statistics for Europe’s vulnerable coastal cities including Barcelona, Istanbul, Dublin and others. With homes, infrastructure and indeed entire economies at stake, it’s crucial for authorities to understand the extent of the risk these cities are facing – and take steps to manage it. </p>
<p>To start with, it’s important to review such claims in detail, as predictions can vary greatly depending on such factors as the warming of the oceans and the melt rate of ice sheets in Greenland and Antarctica. A closer inspection of the BCCC study shows that the authors misinterpreted the data, as <a href="https://link.springer.com/article/10.1007/s10584-016-1703-4">the original source</a> offers a much more conservative sea level rise of 20cm since 1880 – a rate of 1.5mm a year. This falls in the same ballpark as estimates by the Intergovernmental Panel on Climate Change and <a href="http://ukclimateprojections.metoffice.gov.uk">other recent research</a>, making it a more credible figure. </p>
<p>Next, authorities need to understand the nature of the risk associated with sea level rise. While higher sea levels can mean that the ocean encroaches on developed coastal areas, this isn’t the only – or even the most serious – risk. Sea level rise is an important factor in climate change, which also heightens the risk from coastal storms and floods for European coastal cities. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/159554/original/image-20170306-20753-toe7lv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/159554/original/image-20170306-20753-toe7lv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/159554/original/image-20170306-20753-toe7lv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/159554/original/image-20170306-20753-toe7lv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/159554/original/image-20170306-20753-toe7lv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/159554/original/image-20170306-20753-toe7lv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/159554/original/image-20170306-20753-toe7lv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">At risk.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/diluvienne/360227015/sizes/l">diluvienne/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<h2>Stormy seas</h2>
<p>Storminess and the intensity, or “magnitude”, of storms – rather than an increase in their frequency – is difficult to predict because of their natural variability. Predictions tend to rely on complex mathematical models for forecasting. In the UK, for example, scientists from the University of Reading and the Meteorological Office found an <a href="http://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/1/2/recent_storms_briefing_final_slr_20140211.pdf">increase in the number of storms since 1910</a>, in part <a href="http://nora.nerc.ac.uk/515335/1/N515335JA.pdf">due to climate change</a>. But the array of models often show a range of results regarding frequency and magnitude from no change at all, to a more rapid increase throughout the 21st century.</p>
<p>In fact, these storms could lead to greater coastal impact and erosion, as they cause a rapid rise in the average level of the sea, compared to that experienced because of long-term sea level rise. </p>
<p>Across Europe, cities, transport infrastructure and major industry are often located in the coastal zone. These coastal assets are vulnerable to the threat posed by sea level change and storminess. The extreme water level rise associated with storm surges is particularly worrying. A surge associated with a storm in 2005 added 1.5 metres to highest tide across northern Scotland and the Hebrides. And in 2013, a storm in southern England raised water levels at some locations by an additional 5-6 metres. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/159539/original/image-20170306-908-ytjbly.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/159539/original/image-20170306-908-ytjbly.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/159539/original/image-20170306-908-ytjbly.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/159539/original/image-20170306-908-ytjbly.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/159539/original/image-20170306-908-ytjbly.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=493&fit=crop&dpr=1 754w, https://images.theconversation.com/files/159539/original/image-20170306-908-ytjbly.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=493&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/159539/original/image-20170306-908-ytjbly.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=493&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The new normal?</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jomilton/28682838985/sizes/l">hawkflight1066/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Building resilience</h2>
<p>To protect Europe’s coastal cities from such disasters, the European Environment Agency <a href="http://www.eea.europa.eu/highlights/cities-taking-action-learning-from">suggests that</a> authorities should find ways to improve resilience. This means finding ways to adapt to and lessen the impact of climate change, by investing in long-term, preventative measures. </p>
<p>This could mean anything from making improvements to urban planning with key consultation across a range of experts including climate scientists, coastal zone mangers and infrastructure managers, to increasing the number and size of green areas and limiting construction on floodplains. </p>
<p>Specifically, planners need to start moving away from hard engineering solutions such as sea walls and rock armour. Instead, they should consider working with natural processes to increase coastal resilience. For instance, many European coastal areas have extensive wetlands and beach systems, which can provide a natural “buffer” against the impact of sea level rise and intermittent storm surges. </p>
<p>Yet it can be difficult to persuade the inhabitants of coastal zones to have confidence in these “softer” solutions such as beach nourishment and wetland restoration. Education is key here, to explain how these measures can help.</p>
<p>There’s still much progress to be made. Many cities are just beginning to develop and implement strategies to manage the impacts of climate change. These are long-term approaches, not short-term fixes, and as such, it will take time for authorities to gather the necessary political momentum and funds to invest toward mitigating coastal risks. A well-rounded approach which considers natural coastal processes, urban planning and economic vulnerability is crucial to building resilience, and protecting coastal cities from climate change.</p><img src="https://counter.theconversation.com/content/72835/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sue Dawson receives funding from NERC Arctic program to investigate the impact of tsunamis in the northern North Atlantic. This article benefited from discussions with Alastair Dawson, Honorary Professor, University of Dundee.</span></em></p>The real risk is from sudden storms – but there are ways to limit the damage, if cities start planning now.Sue Dawson, Reader in Physical Geography, University of DundeeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/590832016-05-23T02:22:02Z2016-05-23T02:22:02ZCoastal law shift from property rights to climate adaptation is a landmark reform<p>Coastal management in Australia is subject to competing interests and challenges. These range from land use and strategic planning issues to ecosystems preservation. Local councils are at the coalface as both key decision-makers and the first point of contact for communities. </p>
<p>Exacerbating these day-to-day challenges for councils are risks to property. A quantitative assessment undertaken by the then-Department of Climate Change in 2009 identified impacts of sea-level rise as a <a href="https://www.environment.gov.au/climate-change/adaptation/publications/climate-change-risks-australias-coasts">serious threat to property</a>. </p>
<p>In New South Wales, under scenarios of a 1.1-metre sea-level rise, risks of damage or inundation to residential housing alone affected tens of thousands of properties, potentially costing millions of dollars. The NSW 2009 sea-level rise policy (now repealed) saw coastal councils considering this future risk when developing coastal zone management plans. </p>
<p>These metrics, while important, say little of the wide-ranging benefits of a freely accessible coast. Going to the beach is a fundamental part of Australian identity; it’s a “<a href="http://www.australia.gov.au/about-australia/australian-story/beach">special place</a>” for Australians.</p>
<p>Local councils are most exposed to the issues and challenges of a changing coastline in which there are many interests. Councils are often the first decision-makers for local development, asset management and land-use and strategic planning. Increased coastal erosion, storm events, more frequent and severe flooding impacts and higher tides can and will make these regular functions of councils <a href="http://www.ga.gov.au/ausgeonews/ausgeonews201103/climate.jsp">more complicated</a>. </p>
<p>In this context, the tabling of the NSW <a href="https://www.parliament.nsw.gov.au/bills/Pages/bill-details.aspx?pk=3291">Coastal Management Bill</a> on May 3 marks the formalisation of Stage 2 of the most significant law reform to coastal management since the 1970s. The NSW <a href="http://www.environment.nsw.gov.au/resources/coasts/coastreforms-minister-speech-13nov14.pdf">state government says</a> that, by better integrating coastal management with land-use planning, the legislation offers:</p>
<blockquote>
<p>… a modern, coherent coastal management framework that is responsive to current needs and future challenges. </p>
</blockquote>
<h2>Property rights hold sway</h2>
<p>Despite a prominent <a href="http://www.pc.gov.au/inquiries/completed/climate-change-adaptation/report">focus on property values</a> when it comes to coastal management issues, including climate adaptation, evidence is emerging that residents are <a href="http://sydney.edu.au/environment-institute/events/the-small-changes-coastal-vulnerability-to-sea-level-rise/">attached to their property for more than financial reasons</a>. </p>
<p>Private property interests often take priority as councils attempt to balance competing interests. An example of this is ongoing litigation over a sandbag wall on Belongil Beach in Byron Bay.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/123466/original/image-20160523-9520-qv1tf6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/123466/original/image-20160523-9520-qv1tf6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/123466/original/image-20160523-9520-qv1tf6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=623&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123466/original/image-20160523-9520-qv1tf6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=623&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123466/original/image-20160523-9520-qv1tf6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=623&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123466/original/image-20160523-9520-qv1tf6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=783&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123466/original/image-20160523-9520-qv1tf6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=783&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123466/original/image-20160523-9520-qv1tf6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=783&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">With coastal defences failing, some councils are moving to policies of ‘planned retreat’.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:WAVES_EXPLODE_AGAINST_SEAWALL._CHICAGO,_IL._HOUSE_ON_LEFT_IS_THREATENED_BY_BEACH_EROSION._U.S._ARMY_CORPS_OF..._-_NARA_-_547114.jpg">Wikimedia Commons/Paul Sequeira, US EPA</a></span>
</figcaption>
</figure>
<p>After a series of severe coastal storms in the 1970s, Byron Shire Council <a href="http://www.theaustralian.com.au/archive/news/byron-bay-mayor-jan-barham-vows-no-retreat-on-beach-barriers/story-e6frg6o6-1225778397737">adopted a policy of “planned retreat”</a>. The location of this small northern NSW community on the most easterly point of Australia means it is already exposed to coastal hazards. These will become more frequent and more severe under future climate scenarios.</p>
<p>The planned retreat policy set requirements for the future relocation of private property. Local property owners, particularly those with beachfront property, have <a href="http://www.byronnews.com.au/news/planned-retreat-comes-under-fire/261927/">vehemently opposed</a> the use of the policy to prevent coastal property protection. </p>
<p>In May 2009, a particularly severe coastal storm caused significant damage to private residential property and the beach. Beachfront property owners (the Vaughans) sought to reinstate council-approved sandbag protection works on their property. This sandbag wall had collapsed during the storm. </p>
<p>The <a href="http://onlinelibrary.wiley.com/doi/10.1111/1745-5871.12170/abstract">Vaughans sued the council and the council sued the Vaughans</a>. This particular matter settled in February 2010 and the failed sandbag wall has been reinstated. </p>
<p>More recently, council plans to install a <a href="http://www.abc.net.au/news/2015-05-21/belongil-wall/6487246">permanent rock wall at the same location</a> ran into <a href="http://www.echo.net.au/2015/05/protest-planned-against-byron-councillors-rock-wall/">fierce opposition from the community</a>, for whom the public amenity of the beach is critical, and <a href="http://www.edonsw.org.au/positive_change_for_marine_life">legal challenges</a>. </p>
<p>This example highlights some critical aspects of coastal management:</p>
<ul>
<li><p>private property rights are deeply entrenched in Australian culture and legal systems</p></li>
<li><p>climate adaptation is easier when it comes to future development</p></li>
<li><p>recourse to litigation in protecting your property is much easier if you can afford it. </p></li>
</ul>
<p>Climate adaptation planning, including planned retreat, can be more easily implemented for future development. There are <a href="http://www.esc.nsw.gov.au/inside-council/project-and-exhibitions/major-projects-and-works/coastal-projects/sea-level-rise">excellent examples of local government</a> in NSW providing landowners with a range of development options. </p>
<h2>NSW reforms weigh future risks</h2>
<p>Much of the coast of Australia, however, is already developed. The residential development includes <a href="https://www.researchgate.net/profile/Nicole_Gurran/publication/228634993_Planning_for_affordable_housing_in_coastal_sea_change_communities/links/00b4953c1e7805f410000000.pdf">affordable housing options</a>. To balance competing interests along the coast, all members of coastal communities must be considered. </p>
<p>To this end, the NSW bill, if passed, would <a href="http://www.environment.nsw.gov.au/coasts/coastreforms-act.htm">lead to a new Coastal Management Act</a>, a new <a href="http://www.environment.nsw.gov.au/resources/coasts/coastal-management-sepp.pdf">Coastal Management State Environmental Planning Policy</a> and a <a href="http://www.environment.nsw.gov.au/coasts/coastreforms-manual.htm">coastal management manual</a>. Together these advance a more forward-thinking coastal management response. This has a central focus on ecologically sustainable development that can better balance both the management of coastal hazards and the integrity of the coast. </p>
<p>Local councils will be responsible for implementing these new legal requirements. Under Part 3 of the Coastal Management Bill, councils will be required to monitor coastal hazards and to give effect to coastal management plans. It would appear this includes future sea-level rise.</p>
<p>As has been advocated in <a href="https://theconversation.com/coastal-communities-including-24-federal-seats-at-risk-demand-action-on-climate-threats-58764">numerous policy reports</a>, the councils can’t do this alone. They need assistance from the federal government as well as the state.</p><img src="https://counter.theconversation.com/content/59083/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tayanah O'Donnell undertakes research with the University of Canberra funded by the National Climate Change Adaptation Research Facility and the ACT Government. She also the principal of PlaceAdapt Consulting.</span></em></p>Many properties are at risk from rising sea levels, with owners and councils at odds over the costs of defending these. NSW law reform may lead to more forward-looking climate change adaptation.Tayanah O'Donnell, Research Fellow, University of CanberraLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/510512015-12-03T18:53:48Z2015-12-03T18:53:48ZSea level rise is real – which is why we need to retreat from unrealistic advice<figure><img src="https://images.theconversation.com/files/103991/original/image-20151202-14470-1b8hckt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In the aftermath of 2012's deadly Hurricane Sandy, New York launched a US$20 billion plan to defend the city against future storms as well as rising sea levels.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/shankbone/8139676602/in/photolist-dpgYgL-dqicHx-dqTtZX-dpgTrF-doUvuJ-dpcF32-dq4Vwn-dpgQ8a-ds3EdU-dpbZjJ-dqTRT3-dt3Kr7-dp27up-dptDEw-dq1Mgu-dq1M8J-dq1McQ-dpvrMZ-dq4VyH-dpBr3D-dqFS29-dsLUc3-dq1BH2-ffYCde-dtnD3j-dpDt8f-dtn963-dphzd9-dtnDs3-dpgWJx-dr5fQg-dtaJYK-dpcFLg-dtaK1e-drHFBA-dpcFZk-dBX8RL-e15PGF-dp2y2D-dq1LX9-dpbZF5-dBxWSe-dtmnQ8-dph611-dtmv7p-dtaVJh-dtmzFq-dtaVDs-dtaVJN-dtaK12">David Shankbone/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Coastal communities around the world are being increasingly exposed to the hazards of <a href="https://theconversation.com/how-to-make-sense-of-alarming-sea-level-forecasts-45655">rising sea levels</a>, with global sea levels <a href="https://theconversation.com/sea-level-is-rising-fast-and-it-seems-to-be-speeding-up-39253">found to be rising faster</a> over the past two decades than for the bulk of the 20th century.</p>
<p>But managing the impacts of rising seas for some communities is being made more difficult by the actions of governments, homeowners – and even some well-intentioned climate adaptation practitioners.</p>
<p>Coastal adaptation policies usually carry political risk. One of the main risks is when communities end up divided between those wanting a response to the growing risks of coastal flooding, and those more concerned about how their own property values or insurance premiums might be hit in the short-term by such action. For some, the biggest threat is seen to be from sea level rise adaptation policies rather than sea level rise itself.</p>
<p>Some organisations and governments have side-stepped the political risk by commissioning or preparing adaptation plans – but then not implementing them. </p>
<p>A colleague of mine describes this as the “plan and forget” approach to coastal adaptation. It’s all too common, not only here in Australia but internationally. And it can be worse than completely ignoring the risk, because local communities are given the impression that the risk is being managed, when in fact it is not.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/wZXbpBEfojU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The Australian Broadcasting Corporation’s Catalyst program examines past and future sea level rise.</span></figcaption>
</figure>
<h2>‘The road to hell is paved with good intentions’</h2>
<p>Coastal adaptation researchers and practitioners (and I’m one of them) must reconsider some of the common recommendations typically contained in coastal adaptation studies. </p>
<p>In my experience, well-intentioned but poorly considered recommendations – such as advocating for highly urbanised city centres to be relocated inland – prevent many adaptation studies being implemented.</p>
<p>Relocating buildings and other built infrastructure further away from the coast to reduce or eliminate the risk of flooding might sound like a sensible, long-term option, and indeed it is in some cases. </p>
<p>But too often, the advice given to “retreat” or relocate established, highly built-up city blocks makes little economic or practical sense. Such advice can be inconsistent with well-established engineering disaster risk reduction frameworks such as Engineers Australia’s <a href="https://www.engineersaustralia.org.au/sites/default/files/shado/Learned%20Groups/National%20Committees%20and%20Panels/Coastal%20and%20Ocean%20Engineering/climate_change_adaptation_guidelines.pdf">Climate Change Adaptation Guidelines in Coastal Management and Planning</a>.</p>
<p>Much to the chagrin of many in the coastal adaptation science community, cities and owners of major coastal facilities around the world are voting with their feet – largely rejecting coastal retreat recommendations in favour of coastal protection.</p>
<h2>Major cities choosing defence, not retreat</h2>
<p>New York is perhaps the best example of governments and individuals alike choosing protection rather than retreat.</p>
<p>In October 2012, Hurricane Sandy left behind a trail of destruction of more than <a href="http://www.aoml.noaa.gov/hrd/tcfaq/costliesttable.html">US$71 billion</a> in the United States. In New York alone, <a href="http://www.nyc.gov/html/recovery/downloads/pdf/sandy_aar_5.2.13.pdf">43 people were killed</a>.</p>
<p>In June 2013, then <a href="http://www.mikebloomberg.com/news/mayor-bloomberg-outlines-how-to-protect-nyc-against-climate-change/">Mayor Mike Bloomberg</a> said rising temperatures and sea levels were only making it harder to defend New York, warning:</p>
<blockquote>
<p>We expect that by mid-century up to one-quarter of all of New York City’s land area, where 800,000 residents live today, will be in the floodplain. If we do nothing, more than 40 miles of our waterfront could see flooding on a regular basis, just during normal high tides.</p>
</blockquote>
<p>Yet even after acknowledging that threat, New York’s response wasn’t to retreat. Instead, the mayor launched a <a href="http://www.nytimes.com/2013/06/12/nyregion/bloomberg-outlines-20-billion-plan-to-protect-city-from-future-storms.html">US$20 billion plan</a> to protect the city with more flood walls, stronger infrastructure and renovated buildings. As that <a href="http://s-media.nyc.gov/agencies/sirr/SIRR_singles_Lo_res.pdf">“Stronger, More Resilient New York”</a> plan declared: </p>
<blockquote>
<p>We can fight for and rebuild what was lost, fortify the shoreline,
and develop waterfront areas for the benefit of all New Yorkers. The city cannot, and will not, retreat.</p>
</blockquote>
<p>Similarly, none of the winners of <a href="http://www.rebuildbydesign.org/">Rebuild By Design</a> – an international competition to make New York and surrounding regions more resilient to coastal inundation – focused on retreat strategies. In fact, some involve intensifying urban areas that were under water during Hurricane Sandy.</p>
<p>In the worst hit areas, even when given the choice of a <a href="http://stormrecovery.ny.gov/ny-rising-buyout-and-acquisition-programs">state buy-out scheme</a> relatively <a href="http://www.nytimes.com/2013/04/27/nyregion/new-yorks-storm-recovery-plan-gets-federal-approval.html">few New Yorkers</a> chose to <a href="http://citylimits.org/2015/10/14/sandy3-nyc-not-pulling-back-from-the-waters-edge/">leave</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/1pW5MZFU0E8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">PBS Newshour looks at how New York and other world cities can better protect against rising seas and storm surges.</span></figcaption>
</figure>
<p>Although not directly related to climate change, the Japanese response to the devastating 2011 tsunami is another telling example. </p>
<p>There, some residents did choose to relocate to higher ground. However, the government did not relocate major facilities inland, including the Fukushima nuclear facility. Instead, Japan will spend US$6.8 billion to form a <a href="http://www.sciencealert.com/japan-is-building-a-400-km-sea-wall-to-protect-against-tsunamis">400-kilometre-long chain of sea walls</a>, towering up to <a href="http://phys.org/news/2015-03-japan-opts-massive-costly-sea.html">four storeys high</a> in some places.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/AXhjXkd5O7U?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>In Melbourne, Australia, four local councils from <a href="http://abm.org.au/">the Association of Bayside Municipalities</a> worked on the science-based <a href="http://abm.org.au/adaptationproject/">Port Phillip Bay Coastal Adaptation Pathways Project</a> to systematically identify the most effective adaptation responses. That project highlighted the effectiveness of accommodating and reducing flooding through established engineering approaches.</p>
<p>For example, the project concluded that while the popular Southbank waterfront in the City of Melbourne is likely to see even more common and extreme flooding in the coming decades, “<a href="http://abm.org.au/adaptationproject/whatsb.html">retreat is not necessary</a>”.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/104189/original/image-20151203-22464-97lpks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/104189/original/image-20151203-22464-97lpks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/104189/original/image-20151203-22464-97lpks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/104189/original/image-20151203-22464-97lpks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/104189/original/image-20151203-22464-97lpks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/104189/original/image-20151203-22464-97lpks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/104189/original/image-20151203-22464-97lpks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/104189/original/image-20151203-22464-97lpks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Yarra River flows through the heart of Melbourne, in Australia, with Southbank on the left.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/rreeve/21777486105/in/photolist-zbpiUn-zkkTfL-AHhm2J-y2NkfY-ACQ5XT-zDB3Qc-zJsMiS-AEikLb-AEiqys-zX3pqR-zX3p4P-yZ6C49-zBaUrH-z64hm5-yeiQ8J-ywCVLv-yeiF7Y-yehsRj-ywCMKv-ydUEpA-xhJaGa-yeYjkC-vv5weB-wjokqG-w9BCRT-uH8BaY-uvPL59-uL5VZd-uNpDwn-tzpruH-yjvB8u-wSz1SU-wdsD1D-wakJxd-wasmFT-uWvhPE-vwApxc-vbV5ob-uqyrh1-uddvZF-tCyp9G-tX9Z9H-shETGL-rxqTr6-sodm4u-snZ4gN-rttaeP-sqfcDn-tyWF1z-rwByRL">R Reeve/Flicker</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>More practical advice is crucial for greater action</h2>
<p>Coastal adaptation studies and plans need to be based on practical, defensible and implementable recommendations.</p>
<p>That means climate adaptation practitioners need to refrain from recommending that major urbanised coastal centres be relocated further inland in coming decades, unless that really is the only viable option.</p>
<p>Instead, I think we can achieve more by concentrating more on how lower- and medium-density coastal communities can adapt to higher sea levels. This is a more challenging problem, as economic analyses can produce very different recommendations depending on which so-called “<a href="http://economicstudents.com/2013/06/global-warming-externalities-and-government-failure/">externalities</a>” are included or left out in the analysis. </p>
<p>On the same note, adaptation studies that make recommendations without considering the impacts to present-day home-owners, or how adaptation plans are financed, can also be unhelpful.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/74863/original/image-20150315-7058-l65n7s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/74863/original/image-20150315-7058-l65n7s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/74863/original/image-20150315-7058-l65n7s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/74863/original/image-20150315-7058-l65n7s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/74863/original/image-20150315-7058-l65n7s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/74863/original/image-20150315-7058-l65n7s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/74863/original/image-20150315-7058-l65n7s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Florida, USA, photographed from space – one of many highly urbanised coastal areas around the world needing to adapt to rising seas.</span>
<span class="attribution"><a class="source" href="http://eoimages.gsfc.nasa.gov/images/imagerecords/84000/84737/iss041e074232_lrg.jpg">NASA</a></span>
</figcaption>
</figure>
<p>Good adaptation strategies need to acknowledge the real political risks involved with any change involving people and property. Along with making recommendations, they also need to lay out an implementation plan showing how individual and community concerns will be taken into account.</p>
<p>So far the climate models have done a good job in estimating the likely future sea levels. The same cannot be said for our adaptation responses. </p>
<p>But if you’re looking for examples of how we can be better prepared for growing sea level risks, initiatives such as the <a href="http://abm.org.au/adaptationproject/">Port Phillip Bay Coastal Adaptation Pathways Project</a> and the <a href="https://www.ehp.qld.gov.au/climatechange/adaptation.html">Queensland Climate Adaptation Strategy</a> (currently under development) seem to be heading in the right direction.</p><img src="https://counter.theconversation.com/content/51051/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Gibbs receives funding from multiple state and local government sources and private industry to provide advice and expert witness services on coastal management including climate adaptation. Mark is also a Non-Executive Director of Green Cross Australia, and an Adjunct Professor at the Griffith Centre for Coastal Management.
This article was not commissioned by any entity, and solely reflects the individual views of the author.</span></em></p>Managing the impacts of rising seas for some communities is being made more difficult by the actions of governments, homeowners – and even some well-intentioned climate adaptation experts.Mark Gibbs, Director: Knowledge to innovation, Queensland University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/440252015-07-10T05:26:02Z2015-07-10T05:26:02ZBulldozer-driving ‘beach engineers’ might be the unsung heroes of your summer<figure><img src="https://images.theconversation.com/files/87333/original/image-20150703-20448-n5snqb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hard at work, so you can have fun in the sun.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/10047629@N04/8353175312/in/photolist-UNMbd-dJ9d11-7LTDfi">Vetatur Fumare</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Once again the summer holidays have arrived and many people will be jetting off to the beach. However, few tourists will notice the tonnes of sand and gravel that weren’t there the previous year.</p>
<p>Each spring, an army of bulldozers gets to work fixing storm and tidal damage on many of the world’s most famous beaches. Fresh sand or gravel (a term encompassing everything from <a href="http://www.coastalwiki.org/wiki/Gravel_Beaches">tiny pebbles to chunky stones</a>) is placed where necessary, allowing waves and tides to redistribute the material. It can be dumped in the right spots by bulldozers, or shipped in on barges. It can also be pumped in through pipes, as seen in the video below; the mixed-in water is allowed to drain off and the remaining sand is shoved into the right places.</p>
<p>All this is partly driven by the influx of visitors and their rocketing expectations of perfect sand. But beaches aren’t just eye candy for tourists – they themselves have an important role in combating erosion through soaking up wave energy before the sea smashes into the cliffs or seawall. So despite the expense, there’s more demand than ever for what’s known as “beach nourishment”. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Pus_ngzWu2c?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Beach nourishment in Florida.</span></figcaption>
</figure>
<p>If this seems artificial, as though something pristine was being unnecessarily tampered with, then don’t forget beaches weren’t always there. In fact most are relatively new, formed during the past 5,000 or so years after the modern sea level was established. However in recent decades rising sea levels and more frequent storms have led to rapid beach erosion. By the 1990s just 10% of the world’s beaches were still growing, while <a href="http://www.amazon.co.uk/Beach-Management-Coastal-Morphology-Research/dp/0471963372/ref=la_B001H6PYXO_1_3?s=books&ie=UTF8&qid=1436457843&sr=1-3">more than 70% were eroding</a> – with the world still warming and sea levels rising, things will only have got worse since then.</p>
<p>To combat this, beaches such as <a href="http://www.mysuncoast.com/news/local/venice-beach-renourishment-project-underway/article_593612a2-a008-11e4-a2f4-1f8ff47b820a.html">Venice’s Lido</a> or a number along Italy’s north-west coast are “re-nourished” each spring to repair the winter damage. Over the years this adds up. One analysis of the famous beach in Nice, south France, found <a href="http://www.researchgate.net/profile/Francois_Sabatier/publication/229237786_Chronic_offshore_loss_of_nourishment_on_Nice_beach_French_Riviera_A_case_of_over-nourishment_of_a_steep_beach/links/00b4953318db34b6a3000000.pdf">558,000 cubic metres of gravel</a> was added during the 30 years to 2005 – that’s enough gravel to fill up Big Ben’s clock tower <a href="http://www.londoncountyhall.com/localattractions_bigben.html">119 times over</a>.</p>
<p>Along the Costa Brava, on Spain’s north-east coast, entirely artificial beaches have been created, sustained by a combination of breakwaters, groynes (structures built out from the shore to prevent the movement of sediment) and a dump of fresh sand each year.</p>
<p>Perhaps the most famous example of all is the artificial beach in Barcelona, which has been nourished with sand from offshore over the past two decades. The loss of the sediment here is only partially due to storms, with the normal action of the waves causing slow erosion – the area simply isn’t meant to have a massive sandy beach.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/87182/original/image-20150702-11345-17jmkhe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/87182/original/image-20150702-11345-17jmkhe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/87182/original/image-20150702-11345-17jmkhe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=189&fit=crop&dpr=1 600w, https://images.theconversation.com/files/87182/original/image-20150702-11345-17jmkhe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=189&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/87182/original/image-20150702-11345-17jmkhe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=189&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/87182/original/image-20150702-11345-17jmkhe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=238&fit=crop&dpr=1 754w, https://images.theconversation.com/files/87182/original/image-20150702-11345-17jmkhe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=238&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/87182/original/image-20150702-11345-17jmkhe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=238&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The beach at ‘Barceloneta’ was created for the 1992 Olympics.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/ainavidal/11966806096/">Aina Vidal</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In contrast to many other parts of the Mediterranean, the coastline in our home country of Croatia managed to remain more or less natural. Its rocky coastline isn’t ideal for the creation of large sandy beaches, and political upheavals in the 1990s interrupted the growth of tourism. Now the country has once again become a popular tourist destination, and the beauty of its small and well-hidden gravel beaches are a valuable part of its attraction. </p>
<p>Many beaches have therefore been extended or created from scratch, and our current research is focused on the <a href="http://www.research.lancs.ac.uk/portal/en/projects/resilience-of-artificial-gravel-beach-and-implications-for-coastal-management(a3b1a1f7-2c8f-4c6e-abd4-b9976331794a).html">resilience of artificial gravel beaches in Croatia</a>. Their sustainability depends on factors including a continued supply of sediment, and how well they stand up to stormy weather.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/87903/original/image-20150709-10882-1m9kju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/87903/original/image-20150709-10882-1m9kju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/87903/original/image-20150709-10882-1m9kju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1165&fit=crop&dpr=1 600w, https://images.theconversation.com/files/87903/original/image-20150709-10882-1m9kju.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1165&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/87903/original/image-20150709-10882-1m9kju.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1165&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/87903/original/image-20150709-10882-1m9kju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1465&fit=crop&dpr=1 754w, https://images.theconversation.com/files/87903/original/image-20150709-10882-1m9kju.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1465&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/87903/original/image-20150709-10882-1m9kju.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1465&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Computers identify erosion earlier this year on Dugi Rat beach, Croatia.</span>
<span class="attribution"><span class="source">Forthcoming research</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Understanding the behaviour of natural and artificial beaches in different environmental conditions is crucial for their maintenance. A number of techniques are used to detect beach changes including advanced GPS surveys, <a href="http://www.maptek.com/pdf/i-site/case_studies/Maptek_I-Site_beach_erosion_casestudy.pdf">laser scanning</a>, or images from fixed cameras and drones </p>
<p>Our work in Croatia, for instance, uses a simple digital camera combined with advanced computing methods to understand the changing shape of the beach. We also study our nearby coastline in Fylde, Lancashire. With our help, both day trips and holidays to the beach should remain a pleasant feature of our lives into the future.</p><img src="https://counter.theconversation.com/content/44025/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kristina Pikelj receives funding from the Croatian government and Marie Curie Actions- People-2011-COFUND program. </span></em></p><p class="fine-print"><em><span>Suzana Ilic received funding from Wyre Borough Council.</span></em></p>But sandy beaches aren’t just tourist eye candy – they’re a vital defence against coastal erosion.Kristina Pikelj, Research Associate, Lancaster Environment Centre, Lancaster UniversitySuzana Ilic, Lecturer, Lancaster Environment Centre, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/440182015-07-03T04:27:14Z2015-07-03T04:27:14ZWhy Ghana needs a new approach to stop the erosion of its coastline<figure><img src="https://images.theconversation.com/files/87136/original/image-20150702-12365-1bz94ad.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Groynes at the Keta Sea Defense Project on Ghana's coast</span> <span class="attribution"><span class="source">Kwasi Addo Appeaning</span></span></figcaption></figure><p>Ghana’s <a href="http://www.afdb.org/en/countries/west-africa/ghana/ghana-economic-outlook/">economic growth</a> rate is expected to pick up again next year after two years of slowdown following the country’s stellar 7% growth in 2013. But this success has come at a price, particularly to country’s 550km coastline. The coastal zone is inhabited by more than <a href="http://www.statsghana.gov.gh/docfiles/2010phc/2010_POPULATION_AND_HOUSING_CENSUS_FINAL_RESULTS.pdf">one-quarter</a> of Ghana’s population and about 80% of its industrial establishment.</p>
<p>The coastline is home to activities that contribute <a href="http://edition.cnn.com/2015/01/30/africa/ghana-economy-vegetables/">significantly</a> to the national economy. These include oil and gas production, port operations, thermal electricity generation, coastal agriculture, hydroelectricity generation and fishing. </p>
<p>Some of these activities have led to the erosion of Ghana’s coast. Coastal erosion threatens heritage sites dotted along the coast, natural landing sites of the local fishermen and nesting sites of endangered marine turtles, and hinders developing the full potential of the coastal tourism industry. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/87147/original/image-20150702-11303-b50abn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/87147/original/image-20150702-11303-b50abn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/87147/original/image-20150702-11303-b50abn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=415&fit=crop&dpr=1 600w, https://images.theconversation.com/files/87147/original/image-20150702-11303-b50abn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=415&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/87147/original/image-20150702-11303-b50abn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=415&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/87147/original/image-20150702-11303-b50abn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=521&fit=crop&dpr=1 754w, https://images.theconversation.com/files/87147/original/image-20150702-11303-b50abn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=521&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/87147/original/image-20150702-11303-b50abn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=521&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Small scale mining like this is leading to the eroding of Ghana’s coast.</span>
<span class="attribution"><span class="source">Kwasi Appeaning Addo</span></span>
</figcaption>
</figure>
<h2>What’s doing the damage</h2>
<p>The coastal zone is divided into <a href="https://unfccc.int/files/national_reports/non-annex_i_natcom/meetings/application/pdf/20050419armah.pdf">three sections</a> – western, central and eastern. Several activities in these three sections have resulted in changes in the demographic patterns in the coastal zones. </p>
<p>Although the entire coastline is <a href="http://coastalcare.org/2010/12/battling-ghanas-eroding-coastline/">eroding</a> at varying intensity, the eastern section has been identified as the most vulnerable. The area is influenced by the <a href="http://www.geographic.org/geographic_names/name.php?uni=-2885960&fid=1968&c=ghana">Volta Delta</a> system. Erosion rates reached 8m/year after the construction of the Akosombo dam on the Volta river in 1965, which covers an area of [8502 square km](http://www.researchgate.net/publication/222618098_The_role_of_the_Akosombo_Dam_on_the_Volta_river_in_causing_coastal_erosion_in_central_and_eastern_Ghana_(West_Africa). </p>
<p>Oil and gas production in the western section has resulted in increased <a href="https://www.modernghana.com/news/624240/1/oil-and-gas-production-protect-and-compensate-live.html">migration</a> of people to the area in search of jobs. This has increased <a href="http://graphic.com.gh/business/business-news/44711-oil-and-gas-production-threatens-livelihoods-in-coastal-communities.html">stress</a> on the coastal environment and has facilitated changes in the coastal ecology systems. </p>
<p>The migration of people into the area and destruction of vegetation like mangrove swamps <a href="http://onlinelibrary.wiley.com/doi/10.1111/1467-9493.00005/pdf">exacerbate</a> the erosion problems. Mining of precious minerals along portions of the coast destroys the equilibrium of the beach system and either initiates or intensifies the erosion situation.</p>
<p>Sand mining, which is banned but is still <a href="http://graphic.com.gh/features/opinion/20600-coastal-sand-mining-the-greatest-threat-to-the-coastline-of-ghana.html">practised</a> along the entire coast for construction purposes, is also having a negative effect.</p>
<h2>Environmentally unfriendly interventions</h2>
<p>Coastal erosion management in Ghana is reactive, site-specific and usually involves using hard engineering approaches. The current approaches adopted by the government are unsustainable and environmentally <a href="https://books.google.co.za/books?id=dSRFjjvN9aMC&pg=PA112&lpg=PA112&dq=revetments+are+not+environmentally+friendly&source=bl&ots=2TvoQdyQPB&sig=bqLhwWAtIemLXmS-r1smb6GtWSU&hl=en&sa=X&ei=MVaSVd7NCsX5UJqLpeAN&ved=0CCcQ6AEwAg#v=onepage&q=revetments%20are%20not%20environmentally%20friendly&f=false">unfriendly</a>. </p>
<p>Groynes is one such <a href="http://www.bbc.co.uk/schools/riversandcoasts/coasts/change_coast/pg_17.shtml?groyne">approach</a>. This is a form of coastal protection in which barriers are built into the sea to prevent erosion. They essentially trap the sand and stop them from moving too far from the coast. </p>
<p>Concrete or wooden structures, known as <a href="https://geographyas.info/coasts/coastal-management/">revetments</a>, have also been built to act as a barrier against sea waves in a bid to stop the effects of coastal erosion. The revetments absorb the waves energy preventing the cliffs from eroding. </p>
<p>Ghana’s government usually <a href="http://www.ghanaweb.com/GhanaHomePage/election2008/artikel.php?ID=110500">offers</a> groynes and revetments to communities when there has been a complaint. While they stabilise the shoreline at the protected section, they increase erosion <a href="http://www.se-coastalgroup.org.uk/wp-content/uploads/2012/02/Coastal-Defences.pdf">elsewhere</a>. </p>
<p>In addition, major sea defence projects have been carried out by government on sites considered to be highly vulnerable. These include the <a href="http://www.baird.com/what-we-do/project/keta-coastal-defence">Keta Sea Defence Project</a>, <a href="http://backtoghana.com/articles/10/ada-sea-defence-project-to-boost-tourism">Ada Sea Defence Project</a>, <a href="https://www.modernghana.com/news/614649/1/minister-inspects-sakumono-sea-defence-project.html">Sakumono Sea Defence Project</a> and the <a href="http://graphic.com.gh/news/general-news/42949-work-on-sea-defence-projects-in-w-region-progressing-steadily.html">New Toakoradi Sea Defence Project</a>, among others.</p>
<p>These projects involved a combination of revetment and groynes. But the site-specific interventions are having knock-on effects in most cases. The construction of the Keta sea defence, using a combination of groynes and revetments, has led to <a href="http://www.researchgate.net/publication/256756000_Impact_of_sea_defense_structures_on_downdrift_coasts_The_case_of_Keta_in_Ghana">increased</a> coastal erosion on the down-drift coast towards the Ghana–Togo border by over 50%.</p>
<h2>What’s missing</h2>
<p>What is lacking is a comprehensive <a href="http://www.ijser.org/researchpaper%5CA-rapid-overview-of-coastal-erosion-in-Ghana.pdf">management policy</a>. This has prevented the development of a sustainable strategy in managing coastal erosion. </p>
<p>Future projections of erosion along the coast of Ghana indicate that the present coastal buffer zones would be completely <a href="http://www.unep.org/climatechange/adaptation/Portals/133/documents/AdaptCost/9%20Sea%20Level%20Rise%20Report%20Jan%202010.pdf">eroded</a> by 2100. Also, between 2052 and 2082, coastal erosion is projected to catch-up with important landmark features such as the Christiansburg Castle, Ghana’s independence square and the Densu Ramser site in Accra – which are all located within the <a href="http://edition.myjoyonline.com/pages/news/201305/106963.php">coastal zone</a>.</p>
<p>The vulnerability of the coastal zone is expected to <a href="http://www.jamba.org.za/index.php/jamba/article/view/60/212">increase</a> significantly as a result of climate change and its associated sea level rise. Sea level rise will increase the direct inundation of low-lying areas, facilitate rapid erosion of the soft shores and increase offshore loss of sediment as well as flooding. It is estimated that a one metre increase in sea level will inundate a significant <a href="https://inis.iaea.org/search/search.aspx?orig_q=RN:36043428">portion</a> of the Volta Delta system in the eastern section.</p>
<p>There is therefore the need to tackle coastal erosion management from an integrated approach using the green <a href="https://www.rockefellerfoundation.org/blog/communities-build-natural-barriers/">concept</a> of managing with nature and not against it. Adopting the shoreline management plans will enable a large-scale assessment of the risks associated with coastal processes and present a long-term policy framework to reduce these risks to people and the environment.</p><img src="https://counter.theconversation.com/content/44018/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kwasi Addo Appeaning does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Unless something is done to curb erosion, Ghana’s coast could soon whither away.Kwasi Addo Appeaning, Lecturer in Marine and Fisheries Sciences, University of GhanaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/353632014-12-11T19:33:43Z2014-12-11T19:33:43ZComplacency rules as Queensland makes risky edict on sea-level rise<figure><img src="https://images.theconversation.com/files/66950/original/image-20141211-6048-1k8fpmy.jpeg?ixlib=rb-1.1.0&rect=14%2C19%2C1185%2C880&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scarborough, Queensland: no longer allowed to factor in sea-level rise in its planning laws.</span> <span class="attribution"><span class="source">Seo75/Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Queensland Deputy Premier Jeff Seeney’s decision, <a href="http://www.abc.net.au/news/2014-12-09/seeney-removes-climate-change-references-from-council-plan/5954914">revealed this week</a>, to order a Brisbane council to remove future sea-level rise from its planning regulations seems a rather short-sighted thing to do. </p>
<p>His directive, issued to Moreton Bay Regional Council in the city’s north, flies in the face of the overwhelming scientific consensus that average global sea levels will rise by 2100. </p>
<p>For several years, governments across Australia and the world have factored in a sea-level rise of 0.8 m into their coastal planning schemes. The most <a href="http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter13_FINAL.pdf">recent evidence</a> presented by the Intergovernmental Panel on Climate Change suggests that this may even be too conservative.</p>
<p>Yet as certainty over future sea-level rise increases, planning protections are being <a href="http://theconversation.com/scrapping-sea-level-protection-puts-australian-homes-at-risk-21271">wound back right across Australia</a>. Since winning the 2012 Queensland election, Campbell Newman’s government has joined <a href="http://www.afr.com/p/national/nsw_revokes_coastal_erosion_laws_e1v1rvRhQm3NkuQrVkiw3J">New South Wales</a> and <a href="http://www.theage.com.au/victoria/state-eases-sea-level-regulations-20120605-1zu9i.html">Victoria</a> in removing sea-level rise from state government policy, and is evidently now pressing local governments to do the same. </p>
<h2>Planning backflip</h2>
<p>The previous Queensland Labor government had introduced a detailed <a href="http://www.ehp.qld.gov.au/coastalplan/pdf/qcp-web.pdf">Coastal Plan</a>, requiring local governments to plan for a 0.8m sea-level rise by 2100, and featuring detailed mapping of the areas most at risk. </p>
<p>The plan was suspended not long after the election, and when the Newman government released its <a href="http://www.dsdip.qld.gov.au/about-planning/state-planning-policy.html">final policy</a> in December 2013, all references to sea-level rise were omitted. Deputy Premier Seeney <a href="http://www.couriermail.com.au/news/queensland/sea-levels-no-longer-included-in-state-government-planning/story-fnihsrf2-1226778167541">explained his rationale</a> by saying: </p>
<blockquote>
<p>… we believe local governments are the best placed to make planning decisions according to their local circumstances and their communities and we are empowering them to do so.</p>
</blockquote>
<p>Moreton Bay Regional Council made the decision to do just that, incorporating a projected 0.8m sea-level rise into its draft planning scheme. This decision, while attracting the ire of some local residents, was deemed necessary by the Council to protect themselves from a clearly foreseeable liability. </p>
<p>The decision was initially given a green light by Seeney, who in a <a href="https://www.moretonbay.qld.gov.au/uploadedFiles/common/meetings/mbrc/2014/COORDINATION%20CTEE%20Report%20Supporting%20Information%2011%20February%202014.pdf">letter to the council</a> in January 2014 stated that: </p>
<blockquote>
<p>Each coastal local government should proceed to determine the extent of coastal hazards in the manner it considers appropriate and plan accordingly. </p>
</blockquote>
<p>But Seeney has since changed his mind, as a letter made public this week shows (see page 33 of the <a href="https://www.moretonbay.qld.gov.au/uploadedFiles/common/meetings/mbrc/2014/CO20141209_agenda.pdf">council’s minutes</a>). He ordered the council to remove</p>
<blockquote>
<p>…any assumption about theoretical projected sea level rise due to climate change, </p>
</blockquote>
<p>and decreed that the scheme </p>
<blockquote>
<p>…must reflect only proven historical data when dealing with coastal hazards such as storm tide inundation and erosion. </p>
</blockquote>
<h2>Legal implications</h2>
<p>It is unclear whether other coastal councils will be given the same directions, but this decision may signal a broader trend of preventing local governments from planning properly for future sea-level rise.</p>
<p>Legally, Moreton Bay Regional Council might be able to defend itself against claims of negligence by pointing out that a minister ordered it not to include rising seas in its planning scheme.</p>
<p>But the situation is far from clear. Under negligence law, a council may still potentially be held liable for failing to consider the impact of sea-level rise on a particular proposed development, despite the planning scheme being silent on the issue. </p>
<p>Councils thus find themselves in the awkward position of facing appeals from developers if they refuse a proposal on the basis of sea-level rise, but also facing negligence claims in the future if they approve a development that is later affected by rising seas. </p>
<p>New planning legislation will be introduced in Queensland next year, which looks set to remove local governments’ liability for anything done in complying with a minister’s orders. But until then, local governments are in an extremely difficult position.</p>
<h2>Suing the state?</h2>
<p>Even if local governments are let off the hook, the state government could still face negligence claims. The weight of scientific evidence, coupled with the previous government’s efforts to compile sea-level risk data for the entire Queensland coastline, would make such lawsuits very difficult to defend. </p>
<p>Under <a href="https://www.legislation.qld.gov.au/LEGISLTN/CURRENT/C/CivilLiabA03.pdf">Queensland law</a>, government’s actions (or non-actions) are not considered unlawful unless “the act or omission was in the circumstances so unreasonable that no public or other authority having the functions of the authority in question could properly consider the act or omission to be a reasonable exercise of its functions”. But a failure to consider overwhelming scientific evidence may well meet even this very high threshold of unreasonableness.</p>
<p>Even if liability is disclaimed even further, the problem is not going to go away. Experience with past natural disasters such as the 2010-11 Queensland floods shows that, where homeowners are un- or under-insured, governments and taxpayers ultimately end up footing the bill. Buying insurance for actions of the sea is already notoriously difficult, and may become even harder as coastal development continues. </p>
<p>Governments no doubt have challenging decisions to make, and planning for future sea-level rise will not be universally popular. Yes, including sea-level rise may reduce property values and increase insurance premiums. But deferring action will mean that more properties are built in hazard-prone areas. </p>
<p>The time will eventually come when governments cannot ignore this issue, and by then there may be even more properties with reduced value and increased insurance premiums. </p>
<p>Planning for impacts now will let governments spread the huge cost burden of dealing with sea-level rise over time. Waiting will just make the problem even more expensive.</p><img src="https://counter.theconversation.com/content/35363/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Justine Bell receives funding from the Australian Research Council.</span></em></p>Queensland Deputy Premier Jeff Seeney’s decision, revealed this week, to order a Brisbane council to remove future sea-level rise from its planning regulations seems a rather short-sighted thing to do…Justine Bell-James, Postdoctoral Fellow in Law, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/266552014-05-13T15:40:43Z2014-05-13T15:40:43ZCoral reefs work as nature’s sea walls – it pays to look after them<p>Coral reefs: fragile, delicate, and in danger? Actually coral reefs can be the first line in defence against incoming storms, reducing the power of incoming waves by 97%, even during hurricane-force winds. Most (86%) of this wave energy reduction happens at the reef crest, a thin narrow band at the highest point of the reef where waves break first.</p>
<p>Our <a href="http://dx.doi.org/10.1038/ncomms4794">study</a> published in the journal Nature Communications found that the risk reduction provided by reefs is relevant to some 200m people worldwide, and it is these people that may have to bear the costs if reefs continue to be degraded. These are the people in the villages, towns, and cities in low-lying, risk-prone coastal areas below <a href="http://www.maps.coastalresilience.org/global">10 metres elevation and within 50km of coral reefs</a>, mostly in Indonesia, India, and the Philippines. You may be surprised to learn that the US is ranked seventh on this list of nations, due to the high density of cities living near the reefs around south-east Florida. We conducted a more conservative analysis, looking at only those living below 10 metres elevation and within just 10km of a reef, which still represents 100m people. </p>
<p>The risk these people face is growing because of the rate of coastal development and climate change, compounded by reef loss and degradation in tropical areas. Reef degradation, particularly the kind that we have seen <a href="http://www.theguardian.com/environment/2013/aug/01/caribbean-coral-reef-loss">across the Caribbean</a> has particularly devastating effects. Small reductions in the height of reefs, particularly at the reef crest, means substantially greater wave energy passes through the reef to strike the coastline. If you reduce the height of a breakwater that runs the length of your coast by 30cm (12 inches) – and the loss on coral reefs has sometimes measured much more – then you can expect to see a major impact on the coastlines.</p>
<p>But there is reason for optimism. At a time when towns, cities and countries are making major investments in climate and weather-related hazard protection, we found that coral reef protection makes economic, ecological and practical, risk-reduction sense. The average cost of building artificial breakwaters is US$19,791 per metre, compared to $1,290 per metre for projects focused on coral reef restoration. And of course healthy coral also provides a beautiful tourist attraction and has other benefits for fisheries.</p>
<p>But this restoration has to be done properly. Treating coral reef conservation as a joint exercise with storm risk reduction is a new field of science and practical application. It would pay to heed the lessons of past projects that have sought to use other habitats in this way. Tsunamis and storms across the Indian and Pacific oceans in recent years have spurred much interest in <a href="https://theconversation.com/mangroves-natures-shield-against-typhoons-and-tsunami-21051">restoring mangroves as a storm defence</a>, for example, but some of the mangrove restoration has been poorly conceived – for example, by planting mangroves as “bioshields” in places where they did not naturally occur. These projects are doomed to failure as the mangroves generally die.</p>
<p>On this basis, we don’t suggest creating new reefs in places they did not naturally occur. Reef restoration will almost certainly require adding to the height and complexity of existing reefs in order to enhance their wave-breaking power.</p>
<p>There will inevitably be trade-offs to make between the conservation and risk-reduction goals. Cautious conservation may favour using reef rubble or natural materials to grow the reef, but if these are unavailable, cement or rocks might have to do to. To deliver actual risk reduction means improving those reefs that will protect the most people – not necessarily the most remote and diverse reefs that have often been the focus of conservation.</p>
<p>We know that corals can recover. There has been significant recovery in many places around the world from the severe coral bleaching that occurred in the extremely warm <a href="http://www.coralwatch.org/web/guest/coral-bleaching">El Niño year of 1998</a>. Recovery was most sustained where other stresses on the reef, such as pollution, were managed well. Done well, restoring reefs can be money well spent with many benefits.</p>
<p>We shouldn’t be investing just in grey infrastructure like seawalls and breakwaters that will further degrade coastal habitats. Instead we have the opportunity to also invest cost effectively in “blue” ecological infrastructure – the sea wall nature has provided us.</p><img src="https://counter.theconversation.com/content/26655/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Beck does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Coral reefs: fragile, delicate, and in danger? Actually coral reefs can be the first line in defence against incoming storms, reducing the power of incoming waves by 97%, even during hurricane-force winds…Michael Beck, Lead Marine Scientist, The Nature Conservancy, University of California, Santa CruzLicensed as Creative Commons – attribution, no derivatives.