tag:theconversation.com,2011:/us/topics/coasts-1447/articlesCoasts – The Conversation2024-03-28T00:33:06Ztag:theconversation.com,2011:article/2256642024-03-28T00:33:06Z2024-03-28T00:33:06ZCoastal dunes are retreating as sea levels rise - our research reveals the accelerating rate of change<figure><img src="https://images.theconversation.com/files/584278/original/file-20240326-28-gjzijw.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C4000%2C2250&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Patrick Hesp</span></span></figcaption></figure><p>In some parts of Australia, coastal dunes are retreating from the ocean at an alarming rate, as waves carve up the beach and wind blows the sand inland. But coastal communities are largely oblivious to the changes.</p>
<p>Our <a href="https://www.sciencedirect.com/science/article/abs/pii/S0169555X24001156">new research</a> documents the retreat, revealing an accelerating rate of change along Australia’s longest coastal dunefield, in South Australia. These beaches are being reshaped in the geological blink of an eye. </p>
<p>Wave action is eroding the shoreline and the wind is carrying the sand further inland, where new dunes are being formed. Climate change may be <a href="https://theconversation.com/climate-fuelled-wave-patterns-pose-an-erosion-risk-for-developing-countries-184064">accelerating the rate of change</a> by increasing <a href="https://www.science.org/doi/full/10.1126/science.aav9527">ocean wind speeds and wave heights</a>.</p>
<p>This provides yet another reason to reduce emissions and limit global warming – before our beaches and dunes disappear before our very eyes. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/UEykBpCvLEE?wmode=transparent&start=10" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Drone footage from Younghusband Peninsula in South Australia (Patrick Hesp)</span></figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-rising-sea-levels-will-affect-our-coastal-cities-and-towns-221121">How rising sea levels will affect our coastal cities and towns</a>
</strong>
</em>
</p>
<hr>
<h2>Australia’s longest stretch of coastal dunes</h2>
<p>Our South Australian study site, the Younghusband Peninsula, is the longest coastal dune system in Australia. It extends some 190km from the Murray River mouth at Goolwa to Kingston in the state’s southeast. </p>
<figure class="align-left ">
<img alt="Locator maps pinpointing the dune study area, half a mile southeast of 42 Mile Crossing in South Australia" src="https://images.theconversation.com/files/584283/original/file-20240326-30-gbypzc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/584283/original/file-20240326-30-gbypzc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1296&fit=crop&dpr=1 600w, https://images.theconversation.com/files/584283/original/file-20240326-30-gbypzc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1296&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/584283/original/file-20240326-30-gbypzc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1296&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/584283/original/file-20240326-30-gbypzc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1629&fit=crop&dpr=1 754w, https://images.theconversation.com/files/584283/original/file-20240326-30-gbypzc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1629&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/584283/original/file-20240326-30-gbypzc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1629&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The dune study area in South Australia was half a mile southeast of 42 Mile Crossing.</span>
<span class="attribution"><span class="source">Patrick Hesp</span></span>
</figcaption>
</figure>
<p>The shoreline of the central region of the peninsula, near 42 Mile Crossing in the Coorong National Park, started eroding in the early 1980s.</p>
<p>Our new research has found the shoreline has eroded about 100 metres since that time, at an average rate of 1.9m per year. Recently this has become much faster and is now up to 3.3 metres a year. That’s equivalent to losing a tennis court from the front of your house every seven years.</p>
<p>Meanwhile, the dunes are marching inland at an incredible rate of 10 metres a year. </p>
<p>This is an extraordinary rate of change. If the shoreline erosion trend continues, it will dramatically change the national park dune system. </p>
<p>Dune sands may also invade the iconic Coorong Lagoon, impacting the Ramsar-listed wetland of international significance. Sand could slowly fill the lagoon, transforming the environment and reducing the habitat available for fish, waterbirds and other wildlife.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/584299/original/file-20240326-18-ldeufl.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial imagery showing the formation of new sand dunes as the shoreline is eroded by waves" src="https://images.theconversation.com/files/584299/original/file-20240326-18-ldeufl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/584299/original/file-20240326-18-ldeufl.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=275&fit=crop&dpr=1 600w, https://images.theconversation.com/files/584299/original/file-20240326-18-ldeufl.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=275&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/584299/original/file-20240326-18-ldeufl.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=275&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/584299/original/file-20240326-18-ldeufl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=346&fit=crop&dpr=1 754w, https://images.theconversation.com/files/584299/original/file-20240326-18-ldeufl.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=346&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/584299/original/file-20240326-18-ldeufl.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=346&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Contrasting aerial imagery from 1978, 1995, 2005, 2008, 2013 and 2019, showing erosion of the shoreline and formation of new sand dunes.</span>
<span class="attribution"><span class="source">Marcio DaSilva using images from Google Earth</span></span>
</figcaption>
</figure>
<p>Our research also examined how the shoreline has changed over the past 80 years, using <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/esp.5400">aerial photography and satellite imagery</a>, and when the dunes on the Younghusband Peninsula formed, using various dating methods, historical aerial photography from 1945, and satellite imagery. We found they are forming at a very rapid rate. </p>
<p>This new field of coastal dunes developed in just over a decade. The landward edge of the dunefield has moved inland more than 100 metres in eight years.</p>
<p>Three factors may be causing the shoreline erosion and subsequent dune evolution. Offshore reefs that would have protected the coastline have been breaking down. Sea level has been slowly rising since 1920, so higher waves may be reaching the shore. And wave energy has been increasing in the Southern Ocean in the past ten years. </p>
<p><iframe id="tc-infographic-1030" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/1030/4cf3eba59b2b09275ba18abf4e6a63f0c94b2b04/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>Shaping coastal dunes</h2>
<p>Large dune systems are formed by sediment transported by waves from the ocean and the surfzone (where waves break). Once waves deposit the sand on the beach, the wind transports it landwards, creating dunes. </p>
<p>Where large amounts of sediment are delivered to a beach and blown inland, “transgressive” dunes may form. We also examined what drives the development of a transgressive dunefield.</p>
<p>Our research shows there are various factors involved, including:</p>
<ul>
<li>high sediment supply from the nearshore and beach system</li>
<li>rising sea level acting as a marine bulldozer that pushes sediments shorewards</li>
<li>wave scarping (creating steep, precipitous sand cliffs that are then prone to collapse) followed by wind erosion of dunes at the back of the beach</li>
<li>climate change resulting in lower rainfall, stronger winds, and a lowering of the water table, which all affect plant growth.</li>
</ul>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-fuelled-wave-patterns-pose-an-erosion-risk-for-developing-countries-184064">Climate-fuelled wave patterns pose an erosion risk for developing countries</a>
</strong>
</em>
</p>
<hr>
<h2>The eroded area is expanding north and south</h2>
<p>Our continuing observations and fieldwork show beach erosion and scarping now <a href="https://cmi.ga.gov.au/data-products/dea/581/dea-coastlines">extends for several kilometres</a> northwest and southeast of the area near 42 Mile Crossing.</p>
<p>Underlying older dunes are being cannibalised by the wind. As the scarp slope retreats, it supplies sediment that continues <a href="https://www.sciencedirect.com/science/article/abs/pii/S0169555X24001156">building up the dunes</a> and transporting sand landwards across the older dunefield.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/584245/original/file-20240325-30-ap7je9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An oblique aerial view of the study site showing the formation of steep sand cliffs (~12m high) and new sand dunes smothering vegetation inland" src="https://images.theconversation.com/files/584245/original/file-20240325-30-ap7je9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/584245/original/file-20240325-30-ap7je9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/584245/original/file-20240325-30-ap7je9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/584245/original/file-20240325-30-ap7je9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/584245/original/file-20240325-30-ap7je9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/584245/original/file-20240325-30-ap7je9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/584245/original/file-20240325-30-ap7je9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Drone footage shows wave action is forming steep sand cliffs (~12m high). The new sand dunes are cannibalising and migrating over the older vegetated dunes.</span>
<span class="attribution"><span class="source">Patrick Hesp</span></span>
</figcaption>
</figure>
<p>Drone footage shows how wave erosion of the shoreline combined with wind-driven erosion can trigger the creation of a transgressive dunefield. </p>
<p>Our research shows many of the standard assumptions about the development rates and timescales of dunefield evolution may be wrong. If erosion at this site continues to extend north and south, massive changes to the dunefield system, coastal habitats and possibly the Coorong Lagoon may occur. </p>
<p>Such shoreline erosion and dunefield changes suggest what may happen in future to many Australian beach and dune systems as sea levels continue to rise with climate change.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/K7yAXN-9Jjo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Flinders University Professor Patrick Hesp talks about his research into coastal dunes.</span></figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/become-a-beach-scientist-this-summer-and-help-monitor-changing-coastlines-214307">Become a beach scientist this summer and help monitor changing coastlines</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/225664/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Patrick Hesp receives funding from Australian Research Council</span></em></p><p class="fine-print"><em><span>Marcio D. DaSilva 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>Some Aussie beaches are being reshaped and coastal dunes are marching inland. We used data from aerial photography, field surveys, laser mapping and drones to study incredible rates of change.Patrick Hesp, Professor, Flinders UniversityMarcio D. DaSilva, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2219952024-01-31T15:25:44Z2024-01-31T15:25:44ZWetlands are superheroes: expert sets out how they protect people and places<p>In the past, wetlands were often seen as <a href="https://www.iwmi.cgiar.org/Publications/Books/PDF/wetlands-and-people.pdf">undesirable landscapes</a> – waterlogged areas that were difficult to navigate, impossible to build on or farm, and a source of pests such as mosquitoes. But the view on wetlands has shifted as we have learnt how important these ecosystems are for essential “services”. They purify water and provide habitats for plants and animals.</p>
<p>Wetlands are also critical for supporting some people’s livelihoods, particularly in developing countries, including water-scarce countries like <a href="https://www.gov.za/WorldWetlandsDay2024">South Africa</a>. Wetlands provide over <a href="https://www.worldwetlandsday.org/materials#">1 billion livelihoods globally</a>; 660 million people depend on them for aquaculture and fishing. Livestock owners rely on wetlands as a water source for their animals.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/wetlands-do-the-job-of-expensive-technology-if-we-let-them-125452">Wetlands do the job of expensive technology, if we let them</a>
</strong>
</em>
</p>
<hr>
<p>In the last decade, the potential for wetlands to help with climate change adaptation has become more recognised. Wetlands absorb the carbon dioxide (CO₂) that contributes to global warming, and they reduce some of the impacts of climate change by curbing floods. </p>
<p>As a researcher, I led South Africa’s first national assessment of coastal wetlands as <a href="https://theconversation.com/first-study-to-estimate-blue-carbon-storage-in-south-africa-is-useful-for-climate-strategy-195458">“blue carbon”</a> sinks. These are marine habitats that can take up and store more carbon than terrestrial forests. My research has also assessed the impact that climate change will have on <a href="https://theconversation.com/mangrove-forests-wont-be-able-to-spread-further-in-south-africa-so-protecting-them-is-crucial-193547">mangrove forests</a>, otherwise known as coastal wetlands.</p>
<p>This has given me insights into wetlands and their importance in helping prevent the worst effects of climate change.</p>
<h2>Wetlands for people and planet</h2>
<p>Wetlands can provide a “nature-based solution” to assist with climate change, but only if they are protected and managed. For example, wetlands absorb carbon dioxide from the atmosphere (like all plants do), and convert this into organic carbon (which makes up the plant as it grows). This organic carbon is deposited into the wetland mud as the plant grows through seasonal cycles, and the waterlogged conditions help to trap it there and prevent it being released back into the atmosphere. This carbon can be locked up for decades or centuries, which is a meaningful timescale for tackling climate change challenges. </p>
<p>In addition to mitigating climate change, wetlands can help humans to adapt to climate change. Many coastal areas are prone to increased flooding as a result of climate change, due to a combination of higher intensity storms and rainfall as well as rising sea levels. Wetlands are considered “ecological infrastructure” that provides protection from flooding. They have been successfully incorporated into shoreline <a href="https://www.wetlands.org/innovative-solutions-to-reduce-emissions-from-coastal-engineering/">engineering</a>. </p>
<p>Naturally occurring coastal wetlands (such as mangroves and salt marshes) can also buffer the effects of flooding if they are restored and maintained in <a href="https://envirobites.org/2022/05/02/rising-sea-levels-call-for-rising-wetlands/">good condition</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-root-cause-of-flooding-in-accra-developers-clogging-up-the-citys-wetlands-184270">A root cause of flooding in Accra: developers clogging up the city's wetlands</a>
</strong>
</em>
</p>
<hr>
<p>Unfortunately, in many urban areas these wetlands have been lost or replaced with hard infrastructure such as buildings or roads. The protection from wetlands is then lost and flooding or sea-level rise can be more severe. Detailed studies at the <a href="https://www.tandfonline.com/doi/abs/10.2989/16085914.2019.1662763">Knysna</a> and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0272771421003474">Swartkops</a> estuaries in South Africa have shown that salt marshes, another type of wetland, can provide protection from rising sea levels if they are restored. </p>
<h2>What’s missing</h2>
<p>For wetlands to continue to provide these services for climate mitigation and adaptation, their sustainability must be ensured. Many of these steps must be taken at the level of regional or national government, but individual citizens can also get involved. </p>
<p>Some actions that ordinary people can take to help preserve wetlands include:</p>
<ul>
<li><p>educating themselves and others about the value of wetlands</p></li>
<li><p>participating in wetland restoration projects or clean-ups </p></li>
<li><p>directly contributing to organisations that conserve wetlands, such as the <a href="https://sawetlandsociety.org/">South African Wetland Society</a> and <a href="https://www.birdlife.org.za/">BirdLife South Africa</a></p></li>
<li><p>conserving water and reducing pollution from household chemicals </p></li>
<li><p>advocating for planning and zoning of new housing and business park developments that include wetlands in their design.</p></li>
</ul>
<p>Even with adequate protection, the ability of wetlands to provide a variety of important ecological services is also limited by certain thresholds. For example, catastrophic flooding can cause scouring and erosion of wetlands, wiping them out completely.</p>
<p>Careful planning must be put in place to prepare for climate change-caused disasters like this. The complexity of climate change means that solutions need to be complex too: both nature and human engineering are resources for mitigation and adaptation. </p>
<p>Solutions will also need to be designed for local conditions: there isn’t a general solution for the same challenge in different areas. For example, for a solution that involves creating wetlands as <a href="https://iopscience.iop.org/article/10.1088/1748-9326/acfdba/pdf">supporting infrastructure</a>, the size of the wetlands and the number of wetlands can influence how effective the flood mitigation of an area will be in comparison to built infrastructure such as flood control reservoirs and dams. Creating natural infrastructure such as wetlands can provide a cost-effective solution to improve built infrastructure in this way.</p><img src="https://counter.theconversation.com/content/221995/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jacqueline L Raw works for Climate Neutral Group, a part of Anthesis which is the largest group of sustainability consultants globally. She is also a Research Associate at the Nelson Mandela University and has received funding from the National Research Foundation of South Africa. </span></em></p>Wetlands can prevent flooding, trap carbon and support livelihoods, as long as they are protected and managed.Jacqueline L Raw, Carbon Project Developer, Nelson Mandela UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2182672023-11-30T13:35:54Z2023-11-30T13:35:54ZDrone fishing in South Africa is a danger to sharks and may be unfair to other fishers – study<p>“Drone fishing” is a relatively recent innovation in the use of unmanned aerial vehicles. Some recreational anglers are using personal drones to fly baited lines into hard-to-reach areas of water, or to look for good fishing areas. </p>
<p>Recreational fishing is a popular sport and hobby in South Africa, which has a 2,850km shoreline. The most recent estimate of the number of marine shore based anglers is about <a href="https://onlinelibrary.wiley.com/doi/pdf/10.1111/fme.12515">400,000</a>. </p>
<p>The group of researchers I’m part of, who study linefish (fish caught using hook and line) became aware over the past 10 years or so of the increased practice of drone fishing. This was in part thanks to recreational fishers approaching us with their concerns. </p>
<p>One of the concerns is that increases in the numbers of enthusiastic anglers and their ability to catch fish might have significant effects on fish stocks and other animals (such as birds) in coastal zones. Another is that drone fishing might intensify conflict between fisher groups competing for the same species. Aside from recreation, linefishing provides the primary source of <a href="https://www.tandfonline.com/doi/abs/10.2989/1814232X.2020.1824738">protein and income</a> for about 2,730 commercial fishers, 2,400 small-scale boat fishers and 30,000 small-scale shore-based fishers in South Africa. </p>
<p>We agreed the practice should be investigated, but faced a challenge: there was very little monitoring going on to provide data. </p>
<p>So we took an unconventional approach to our <a href="https://link.springer.com/article/10.1007/s13280-021-01578-y#Sec11">study</a>. We used publicly available online monitoring to estimate the growing interest, global extent and catch composition of drone fishing. This showed us that there had been a big (357%) spike in interest in drone fishing in 2016. There were also worrying indications of a threat to species of conservation concern in South Africa. </p>
<p>We then consulted commercial drone operators, legal researchers and others to get a more holistic view. Drone fishing has economic, political, legal, ecological and physiological implications. Based on this we made some recommendations for further research and monitoring, and shared them with fishing authorities.</p>
<p>The South African Department of Forestry, Fisheries and the Environment then released a <a href="https://www.dffe.gov.za/sites/default/files/legislations/publicnotices/25february2022motorisedequipment_recreationalangling.pdf">public notice</a> warning recreational anglers that the use of drones and other electronic devices is deemed illegal under the <a href="https://www.gov.za/documents/marine-living-resources-act-27-may-1998-0000">South African Marine Living Resources Act</a>.</p>
<p>The fishing drone companies that had already emerged are now struggling to survive. They have taken the department to <a href="https://www.saflii.org/za/cases/ZAGPPHC/2022/250.html">court</a> seeking clarity on the legality of using drones in fishing. The judgement on this case, which is currently in the appeal court, will no doubt pave the way for how drone fishing is managed in South Africa in the future.</p>
<h2>Innovative research methods</h2>
<p>Largely because we were house-bound during the 2020-2021 COVID-19 pandemic we gathered most of our data via the internet. We surveyed social media platforms for drone-fishing dedicated groups and used Google Trends to track internet searches for “drone fishing”.</p>
<p>Results indicated a 357% spike in interest in 2016, after the release of a popular YouTube <a href="https://www.youtube.com/watch?v=8sdUZqOoAq4">video</a> of an angler catching a large longfin tuna from an Australian beach using a drone. The search volume increased to about 3,600 monthly searches from an average of about 1,400 before the peak. “Drone fishing” Facebook groups had over 17,000 members and 38,700 videos with titles including the term “drone fishing” had been uploaded. </p>
<p>The online interest was mostly in three countries: New Zealand, South Africa and Australia. </p>
<p>To get an idea of which fish species were targeted, we then watched 100 YouTube videos posted by drone fishers in those three countries. In both New Zealand and Australia, the most frequently observed catch was red snapper, which is not a species of direct conservation concern. In South Africa, though, sharks made up the majority (97%) of viewed catches, many of which are of severe conservation concern, such as the <a href="https://www.iucnredlist.org/species/3852/2872747">dusky shark</a>. </p>
<h2>Impacts of drone fishing</h2>
<p>Having established interest in and the presence of drone fishing in South Africa, we sought to consider the issue holistically – its impact on:</p>
<ul>
<li><p>targeted fish and their habitats</p></li>
<li><p>other animals in the coastal zone</p></li>
<li><p>other people using the coastal zone.</p></li>
</ul>
<p>Drones with cameras allow anglers to <a href="https://www.instagram.com/reel/Cz8sBz7ihYb/?igshid=MTc4MmM1YmI2Ng%3D%3D">identify</a> ideal fishing habitats far from the shore. Areas that anglers couldn’t reach before are now open to exploitation. Even fish that are released are less likely to survive when caught further offshore. A large fish hooked hundreds of metres offshore is likely to experience <a href="https://www.int-res.com/articles/meps2013/496/m496p207.pdf?">extreme exhaustion and physiological disturbance</a> and may be consumed by other predators. </p>
<p>The potential loss of fishing tackle by drone anglers is also a concern. It is common to lose tackle, either when it gets stuck in rocky habitats or while fighting large fish such as sharks. Both scenarios may result in hundreds of metres of fishing line remaining in the ocean. In addition to polluting the marine environment, such debris threatens to entangle birds, marine mammals and turtles. </p>
<p>In South Africa, drone fishing is only accessible to affluent anglers. Their increased catches might lead to conflict with fishers who depend on their catch for food or income.</p>
<p>It’s also possible that sharing live information on fishing conditions via the internet could add to concerns about the privacy of other public beach users.</p>
<p>Our 2021 <a href="https://link.springer.com/article/10.1007/s13280-021-01578-y#Sec11">paper</a> noted that at the time, there were no specific regulations relating to drone fishing in any country, including South Africa. We drew attention to legislation that could be used indirectly to regulate the practice. </p>
<h2>Regulation and management of fisheries</h2>
<p>Three of the paper’s co-authors were part of a working group for the South African Department of Forestry, Fisheries and the Environment. We shared the paper with the department and in 2022, it took concrete action on this issue for the first time. </p>
<p>The department released a <a href="https://www.dffe.gov.za/sites/default/files/legislations/publicnotices/25february2022motorisedequipment_recreationalangling.pdf">public notice</a> which explicitly prohibits drones and other remotely operated vehicles for angling. </p>
<p>Companies that custom build fishing drones were granted <a href="https://www.gov.za/speeches/use-motorised-equipment-recreational-angling-drones-and-remotely-operated-devices-and-or">leave to appeal</a> the original court ruling on their application to unban drone fishing. The appeal has not yet been heard.</p>
<p>We hope the end result will be better monitoring and management of South African recreational fishery, so that resources are available to those who need them the most.</p><img src="https://counter.theconversation.com/content/218267/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alexander Claus Winkler 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>Increased interest in recreational fishing with drones has led to concern about its environmental and social impact.Alexander Claus Winkler, Research Associate, Rhodes UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2173532023-11-16T22:57:51Z2023-11-16T22:57:51ZLet coastlines be coastlines: How nature-based approaches can protect Canada’s coasts<p>Along Canadian coasts, <a href="https://www.queensu.ca/gazette/stories/climate-change-means-atlantic-canada-will-see-more-frequent-storms">storm surges</a> and <a href="https://www.uottawa.ca/environment/blog/100-year-floods-are-increasing-canada-due-climate-change-officials-say-true">flooding</a> have gone from breaking news to seasonal norms. </p>
<p>Phenomena Canadians have historically thought of as freak <a href="https://doi.org/10.1080/24694452.2020.1744423">natural disasters are becoming regular predictable occurrences</a>. </p>
<p>Our go-to solution to protect property and infrastructure is to build walls to block wave energy — walls that have become <a href="https://www.researchgate.net/profile/Ca-Vu/publication/346517536_Coastal_Development_Resilience_Restoration_and_Infrastructure_Requirements_LEAD_AUTHORS_About_the_High_Level_Panel_for_a_Sustainable_Ocean_Economy/links/5fc5e73992851c3012995ca6/Coastal-Development-Resilience-Restoration-and-Infrastructure-Requirements-LEAD-AUTHORS-About-the-High-Level-Panel-for-a-Sustainable-Ocean-Economy.pdf">ineffective and unaffordable</a>. It’s time to look beyond the status quo and consider <a href="https://www.csagroup.org/article/research/nature-based-solutions-for-coastal-and-riverine-flood-and-erosion-risk-management/">nature-based solutions</a> to protect the places we love.</p>
<h2>How we got here</h2>
<p>In many parts of the world, humans have long felt a <a href="https://press.uchicago.edu/ucp/books/book/chicago/H/bo14312647.html">strong connection to the coast</a>. We <a href="https://doi.org/10.1016/B978-0-323-95227-9.00007-5">write stories, sing songs and build lives</a> on the lands that touch the sea. We also build walls and other concrete, stone and metal structures to <a href="https://oceanservice.noaa.gov/facts/shoreline-armoring.html">protect those lands</a> from the very seas we revere.</p>
<p>From time immemorial, Indigenous Peoples made their homes along the coasts, becoming <a href="https://pressbooks.bccampus.ca/knowinghome/chapter/chapter-7/">experts in their knowledge</a> of coastal ecosystems and, on the Atlantic and Pacific coasts, used <a href="https://www.ubcpress.ca/against-the-tides">salt marshes for food and transportation</a>. Following European settlement, those salt marshes were drained, <a href="https://www2.gov.bc.ca/gov/content/environment/air-land-water/water/drought-flooding-dikes-dams/integrated-flood-hazard-management/dike-management#:%7E:text=Dike%20consequence%20classification-,History%20of%20dikes%20in%20B.C.,relatively%20little%20damage%20was%20caused.">dykes</a> were built from earth and wood, and the land was cultivated for agriculture.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/storms-or-sea-level-rise-what-really-causes-beach-erosion-209213">Storms or sea-level rise – what really causes beach erosion?</a>
</strong>
</em>
</p>
<hr>
<p><a href="https://books.google.ca/books?hl=en&lr=&id=AjwPEAAAQBAJ&oi=fnd&pg=PP1&dq=how+much+of+Canada%27s+coast+is+hardened+shoreline&ots=ofxRgZFp1q&sig=pudIoHph4rwpz4E5hntGfVx36uc#v=onepage&q=how%20much%20of%20Canada's%20coast%20is%20hardened%20shoreline&f=false">Over time, other hard armour structures</a> such as <a href="https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/agriculture-and-seafood/agricultural-land-and-environment/water/drainage-management-guide/533410-1_rock_revetments-drainage_guide_factsheet_no12.pdf">revetments</a> and <a href="https://www.britannica.com/technology/breakwater">breakwaters</a> were constructed to block wave energy and provide additional protection for agriculture, transportation and growing cities.</p>
<h2>Where we are now</h2>
<p>Today, Canada’s coastal infrastructure includes extensive networks of seawalls, dykes, revetments and breakwaters, most of which are made of hard materials. Hard coastal infrastructure is everywhere if you know where to look. The <a href="https://transcanadahighway.com/nova-scotia/canso-causeway/">Canso Causeway</a> connecting Cape Breton Island to mainland Nova Scotia and the <a href="https://vancouver.ca/parks-recreation-culture/seawall.aspx">Vancouver seawall</a> are just two examples. </p>
<p>In some cases, using <a href="https://www.jstor.org/stable/48703231?seq=2">hard infrastructure</a> is unavoidable. Indeed, <a href="https://nrc.canada.ca/en/research-development/research-collaboration/programs/ocean-program-coastal-resilience-technology-theme">hard infrastructure</a> is critical for maintaining transportation and energy infrastructure, including roads, railroads and ports. </p>
<p>However, hard infrastructure almost always <a href="https://www.intactcentreclimateadaptation.ca/rising-seas-and-shifting-sands-combining-natural-and-grey-infrastructure-to-protect-canadas-eastern-and-western-coastal-communities/">increases erosion</a> in adjacent areas, is expensive to maintain and degrades over time. Engineers predict that repairs, including <a href="https://www2.gnb.ca/content/dam/gnb/Departments/trans/Chignecto/chignecto-isthmus-project-report-e.pdf">raising the dykes along the Chignecto Isthmus</a> between New Brunswick and Nova Scotia, will cost between $189-300 million. </p>
<p>With such an astronomical price tag, even smaller projects are simply not an option for many municipalities or individual landowners.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/coastal-erosion-is-unstoppable-so-how-do-we-live-with-it-186365">Coastal erosion is unstoppable – so how do we live with it?</a>
</strong>
</em>
</p>
<hr>
<p>In the face of such challenges, there are opportunities to adapt engineering and protective infrastructure to be more sustainable by integrating natural elements and processes.</p>
<h2>Nature-based solutions</h2>
<p><a href="https://www.transcoastaladaptations.com/nature-based-climate-change-adaptation">Nature-based approaches</a> preserve or reintroduce natural structures and materials into the environment, recognizing and respecting natural systems and their benefits for humans. </p>
<p>Nature-based approaches range from those that are entirely natural to hybrid solutions, which incorporate traditional hard engineering with natural features.</p>
<p>Examples of nature-based solutions <a href="https://static1.squarespace.com/static/5c83d5c63560c33561cc74de/t/61aeca0bf994d4620c5aba87/1638844941547/MRfM_BelcherStMarsh_Case_Study_Final__Dec_05_21_Updated.pdf">include</a> dyke realignment to restore natural water flow and allow saltmarsh reestablishment, wetland and dune restoration, and living shorelines which utilize plants, sand and rock to protect the coast. </p>
<p>Nature-based approaches can involve <a href="https://doi.org/10.1016/j.nbsj.2022.100044">reserving land for natural systems by protecting them from development</a> and making room for the evolution of natural systems; they can also <a href="https://doi.org/10.1016/j.landusepol.2021.105960">involve moving back from the coast, and releasing land back to nature</a>.</p>
<p>Hard infrastructure weakens over time while nature-based solutions grow stronger as plants establish roots, biodiversity increases and natural processes adjust. </p>
<p>Nature-based solutions provide a wide array of benefits. In addition to protecting coastal places from flooding, storm surges and erosion. Nature-based solutions <a href="http://stewardshipcentrebc.ca/PDF_docs/greenshores/Resources/Green%20Shores%202020_%20Impact,%20Value%20and%20Lessons%20Learned_%20Full%20Report_July2020.pdf">prevent shoreline pollution</a>, <a href="https://www.mdpi.com/2071-1050/10/2/523/htm">support biodiversity</a>, can <a href="http://stewardshipcentrebc.ca/PDF_docs/greenshores/Resources/Green%20Shores%202020_%20Impact,%20Value%20and%20Lessons%20Learned_%20Full%20Report_July2020.pdf">increase property value</a> and contribute to overall <a href="https://doi.org/10.3390/su131910950">human well-being</a>. </p>
<p>Incorporating nature-based solutions requires innovation and open-mindedness that may feel intimidating and it is often <a href="https://web.archive.org/web/20220329065340id_/https:/nhess.copernicus.org/preprints/nhess-2022-104/nhess-2022-104.pdf">easier to trust a stone or concrete wall</a> over the energy absorbing power of plants and soil. </p>
<p>As such, <a href="https://doi.org/10.1016/j.nbsj.2022.100044">raising awareness</a> about different nature-based options and being transparent about <a href="https://doi.org/10.1098%2Frstb.2019.0120">costs and benefits</a> can help build confidence in nature-based solutions. </p>
<p>Successful nature-based solutions also require place-based <a href="https://web.archive.org/web/20220329065340id_/https:/nhess.copernicus.org/preprints/nhess-2022-104/nhess-2022-104.pdf">collaboration and knowledge sharing</a> between impacted peoples, engineers, scientists and decision-makers that consider social
and ecological interests. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/st-lawrence-shoreline-erosion-we-must-work-with-not-against-nature-184721">St. Lawrence shoreline erosion: We must work with, not against, nature</a>
</strong>
</em>
</p>
<hr>
<p><a href="https://royalsociety.org/topics-policy/projects/biodiversity/nature-based-solutions/">Nature-based solutions cannot be prescribed as top-down interventions</a>. Every situation is unique, and many people with diverse knowledge and perspectives should come together to decide how specific nature-based approaches can meet various infrastructure, ecological and social needs as well as increase flood resilience.</p>
<h2>What now?</h2>
<p>For natural resource and permitting agencies, as well as many property owners, the tradition of building hard armoured shorelines remains deeply ingrained. Current guidance documents, policies and habits were built for hard infrastructure. In some cases, <a href="https://doi.org/10.3390/su11236735">bureaucratic decision-making structures</a> move slower than hazards from flooding. </p>
<p>In other cases, including lack of or delayed implementation of legislation, such as <a href="https://www.halifaxexaminer.ca/government/province-house/houston-government-once-again-delays-implementation-of-coastal-protection-act/">the Coastal Protection Act</a> and regulations in Nova Scotia, <a href="https://ecologyandsociety.org/vol28/iss2/art25/">political interests</a> hinder planning actions that would limit hard infrastructure and development along the coast.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/iXkrS1u5fl8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">An overview of the problems of erosion facing many communities across Canada, particularly in the North. Produced by the CBC.</span></figcaption>
</figure>
<p><a href="https://climatechoices.ca/wp-content/uploads/2021/09/Infrastructure-English-FINAL-Sep29.pdf?utm_source=vancouver%20is%20awesome&utm_campaign=vancouver%20is%20awesome%3A%20outbound&utm_medium=referral">Many Canadians</a> are buying homes in areas with high flood risk. The infrastructure they rely upon is <a href="https://changingclimate.ca/national-issues/chapter/2-0/">aging</a> and requires adaptation. Infrastructure supporting <a href="https://highways.dot.gov/public-roads/autumn-2021/02">bridges, roads</a> and <a href="https://doi.org/10.1016/j.nbsj.2022.100013">rail lines</a> needs to be upgraded or removed, providing opportunities to incorporate nature-based solutions.</p>
<h2>Hope for the future</h2>
<p>As we look towards what can feel like an ominous future, there are many resources for individuals or organisations seeking additional information and guidance about nature-based solutions. <a href="https://www.transcoastaladaptations.com/">TransCoastal Adaptations: Centre for Nature-based Solutions</a> is a practitioner, academic and government partnership in Nova Scotia focused on restoration, managed realignment and climate change adaptation. </p>
<p>Privately owned companies, also in Nova Scotia, <a href="https://helpingnatureheal.com/">Helping Heal Nature</a> and <a href="https://www.cbwes.com/">CB Wetlands and Environmental Specialists</a>, focus on ecological restoration, living shorelines and community stewardship and education. Nation-wide <a href="https://coastalzonecanada.org/nbcs/">communities of practice</a> exist to build capacity for natural and nature-based approaches.</p>
<p>As more people learn about nature-based solutions, there will be more opportunities to incorporate natural processes into coastal protection. We know the stakes, and we have nature-based solutions at hand. It’s time to give dirt and plants a chance.</p><img src="https://counter.theconversation.com/content/217353/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Keahna Margeson receives funding from the Ocean Frontier Institute Ocean Graduate Excellence Network, Canada First Research Excellence Fund, Social Sciences and Humanities Research Council, and National Research Council Canada. </span></em></p>As seas rise, it is clear that traditional coastal defence approaches are unable to keep pace. Nature-based solutions offer considerable potential to protect coasts, people and biodiversity.Keahna Margeson, IDPhD Student, School for Resource and Environmental Studies, Dalhousie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2089222023-07-21T12:28:45Z2023-07-21T12:28:45ZRip currents are dangerous for swimmers but also ecologically important – here’s how scientists are working to understand these ‘rivers of the sea’<figure><img src="https://images.theconversation.com/files/537611/original/file-20230716-21935-qbqsh8.jpeg?ixlib=rb-1.1.0&rect=7%2C15%2C5168%2C3430&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The gap between breaking waves in North Carolina indicates a rip current flowing away from shore.</span> <span class="attribution"><a class="source" href="https://www.weather.gov/images/safety/photo/rip_nc18-1.JPG">National Weather Service</a></span></figcaption></figure><p>If you’ve ever waded into the ocean for a swim and suddenly realized that the shore is getting farther away, not closer, you may have encountered a rip current. Common at beaches worldwide, these powerful currents flow from the shore toward the sea at speeds up to several feet per second.</p>
<p>It’s important to know what rip currents are and how to <a href="https://oceantoday.noaa.gov/ripcurrentscience/">look for them</a>, because they are a <a href="https://www.washingtonpost.com/nation/2023/06/30/florida-beach-drownings-currents/">leading cause of drownings</a> in the surf zone near shore. According to one recent estimate, rip currents have accounted for <a href="https://floridapanhandle.com/blog/rip-current-statistics/">435 drownings in the U.S. since 2017</a>.</p>
<p>National Weather Service offices that serve coastal communities issue forecasts that predict where and when rip currents are likely to occur. Those forecasts draw on <a href="https://doi.org/10.1016/j.earscirev.2016.09.008">decades of research</a> into the physics of rip currents. Many scholars, including our research group, are finding innovative ways to discover more about rip currents – including their important roles in coastal marine ecosystems. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/RJ4hcaJ91TY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Rip currents are narrow currents in the surf zone that move quickly away from shore.</span></figcaption>
</figure>
<h2>Not all rip currents are the same</h2>
<p>All rip currents have similar effects, but they can form in several ways. </p>
<p>One type of rip, known as a bathymetric or <a href="https://www.weather.gov/safety/ripcurrent-science">channel rip current</a>, forms when there are gaps between breaking waves. As waves break, they push water toward the beach and raise the level of the water slightly. </p>
<p>If waves break on a sandbar, but not in a deeper channel that cuts through the sandbar, the extra water that the waves have pushed toward the beach escapes back to the ocean through the channel. The flow of the escaping water acts like a conveyor belt, moving water, unsuspecting swimmers and small marine organisms offshore. </p>
<p>Another type, known as a transient or <a href="https://www.weather.gov/safety/ripcurrent-science">flash rip current</a>, forms when surf is choppy. The edges of breaking waves push on the water and make it spin, like a fast ice skater bumping into someone. </p>
<p>This creates whirls known as eddies, which can combine to form larger whirls, with currents that act like temporary conveyor belts. Flash rip currents are an active area of research. </p>
<h2>Swim, float, call for help</h2>
<p>Choosing beaches with lifeguards and paying attention to <a href="https://www.weather.gov/media/tae/RipCurrentFlags.pdf">beach flag warnings</a> are the best ways to avoid rip currents. However, if you get caught in one, here are some techniques for getting safely back to shore. </p>
<p>Think of a rip current as a swift river cutting through the surf away from the shore. Swimming against the current is going to tire you out and put you at risk of drowning. Instead, swim parallel to the beach – think of heading for the “river banks” – until you are out of the rip current’s pull. Once you’re no longer fighting it, you can swim back to shore. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A barricaded pathway to a beach with a sign warning of drowning risk and barring swimming and surfing." src="https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537619/original/file-20230716-138859-f52ks8.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">New York City closed public beaches in September 2019 after Hurricane Dorian caused strong rip currents along the Atlantic coast.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/sign-alerts-beach-goers-at-rockaway-beach-that-swimming-and-news-photo/1172788123">Spencer Platt/Getty Images)</a></span>
</figcaption>
</figure>
<p>Another strategy is to float until the rip current carries you offshore beyond the breaking waves. Rip currents slow down here, so you can swim away from the rip current and back to shore. </p>
<p>If you believe you’re in danger, try to stay calm. Wave your arms and call for help. If you see someone caught in a rip current, throw them a flotation device and alert a lifeguard. </p>
<h2>Forecasting rip currents</h2>
<p>The National Oceanic and Atmospheric Administration’s <a href="https://www.weather.gov/beach/">rip current hazard model</a> provides advance forecasts of the likelihood of encountering hazardous rip currents given wave conditions at specific beaches. NOAA works continually to make these hazard forecasts more accurate, including through an ongoing partnership with the <a href="https://www.usla.org/">U.S. Lifesaving Association</a>. This partnership works to compare modeled predictions with lifeguard reports of rip current hazards and to recalibrate the model for different regions and waves. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1678467698731409408"}"></div></p>
<p>At the University of Washington, we are <a href="https://doi.org/10.1175/WAF-D-17-0076.1">evaluating NOAA hazard forecasts</a> against the latest rip current science. This helps us assess predictions for different types of rip currents, such as unexpected flash rips. </p>
<p>To measure rip currents, we sometimes put on scuba gear and battle the waves to set up <a href="https://www.whoi.edu/oceanus/feature/the-riddle-of-rip-currents/">instruments in the surf</a>. But this work can be expensive, and it relies on knowing where rips will occur beforehand. That isn’t possible for flash rips, so we need different methods to analyze those.</p>
<p>We use supercomputers and <a href="https://engineering.oregonstate.edu/wave-lab">massive wave tanks</a> the size of an Olympic swimming pool, with paddles at one end that produce waves, to simulate flash rips. <a href="https://doi.org/10.1016/j.coastaleng.2023.104327">Wave tank laboratory experiments</a> and <a href="https://ui.adsabs.harvard.edu/abs/2022AGUFMOS42A..06N/abstract">computer simulations</a> allow us to control the types of waves we produce and make it easier to collect a lot of data. This work is improving our understanding of the relationship between wave conditions and flash rips, which can help improve hazard predictions. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Waves in a large laboratory tank, stained with pink dye to track currents." src="https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=285&fit=crop&dpr=1 600w, https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=285&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=285&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=358&fit=crop&dpr=1 754w, https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=358&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/538371/original/file-20230719-27-t5e2i1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=358&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pink dye exits the surf in a flash rip current (yellow arrow) during large-scale wave tank experiments.</span>
<span class="attribution"><span class="source">Christine Baker</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Expressways for marine life</h2>
<p>Rip currents aren’t just a safety issue. Scientists are beginning to better understand the crucial ecological role they play in <a href="https://doi.org/10.1146/annurev-marine-010816-060514">redistributing small marine organisms</a>, as well as plastic, pollutants, sediment and debris in coastal waters. </p>
<p>Many marine organisms, including oysters, barnacles, fish and coral, rely on <a href="https://tos.org/oceanography/assets/docs/20-3_pineda.pdf">ocean currents during their larval stage</a> to find suitable habitats. These organisms swim up or down or attach to floating or sinking material and are transported by <a href="https://doi.org/10.1146/annurev-marine-032122-115057">multiple ocean processes</a>. </p>
<p>Rip currents are a <a href="https://doi.org/10.1002/ecm.1265">key mechanism</a> for dispersing larvae to deeper waters or recirculating them in shallow waters. The rip current type and behavior may affect the movement of marine organisms. </p>
<p>Water temperature and salinity can change the behavior of rip currents – and send organisms on alternate routes – by modifying the water’s density. Our group has analyzed <a href="https://doi.org/10.1029/2020GL091675">imagery taken from low-flying planes</a> and found that warmer rip currents carry water farther offshore at the surface, whereas <a href="https://doi.org/10.1002/2017GL072611">cooler rip currents</a> spread beneath the surface in different patterns.</p>
<p>Our research group and other scientists are using computer simulations and numerical “larvae” to investigate how temperature, <a href="https://pinc.ucsd.edu/">salinity</a> and other factors may affect transport of marine organisms. With better understanding of these surf-zone conveyor belts, we aim to help keep swimmers safe and assess how rip currents affect aquatic ecosystems near the shore.</p><img src="https://counter.theconversation.com/content/208922/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emma Shie Nuss receives funding from National Science Foundation and the Office of Naval Research. </span></em></p><p class="fine-print"><em><span>Audrey Casper receives funding from the National Science Foundation and the Office of Naval Research.</span></em></p><p class="fine-print"><em><span>Christine M. Baker receives funding from the National Science Foundation and a Department of Defense National Defense Science and Engineering Graduate Fellowship.</span></em></p><p class="fine-print"><em><span>Melissa Moulton receives funding from the National Science Foundation and the Office of Naval Research. </span></em></p><p class="fine-print"><em><span>Walter Torres receives funding from the National Science Foundation and the Office of Naval Research. </span></em></p>Rip currents are a leading cause of near-shore drownings, but there are effective ways to survive one. And these phenomena also play important ecological roles that are an emerging research area.Emma Shie Nuss, PhD Student in Civil and Environmental Engineering, University of WashingtonAudrey Casper, Data Analyst, NOAA Hazard Forecasting, University of WashingtonChristine M. Baker, Postdoctoral research scholar, North Carolina State UniversityMelissa Moulton, Research Scientist/Engineer, Applied Physics Laboratory, University of WashingtonWalter Torres, Postdoctoral Scholar, Applied Physics Laboratory, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2054732023-05-22T20:06:18Z2023-05-22T20:06:18ZFrom mangroves to fjords, coastal ecosystems can take up or emit greenhouse gases. But globally, they’re a vital sink<figure><img src="https://images.theconversation.com/files/527453/original/file-20230522-27-9rsw0s.jpg?ixlib=rb-1.1.0&rect=1844%2C0%2C4083%2C2778&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Coastal ecosystems can absorb or emit the three main greenhouse gases: carbon dioxide, methane and nitrous oxide. </p>
<p>We explored how coasts in ten regions of the world differ in greenhouse gas uptake and emissions. Our research <a href="https://www.nature.com/articles/s41558-023-01682-9">published today</a> in Nature Climate Change finds that, globally, our coastal ecosystems are a net greenhouse gas sink, but smaller emissions of potent methane and nitrous oxide gases reduce some of the carbon dioxide uptake.</p>
<p>We found coasts in Europe and Russia are net emitters, while coasts in Southeast Asia and North America have a large uptake of these gases. </p>
<p>Like upland forests and rainforests, ecosystems like coastal wetlands can take up atmospheric CO₂ and turn it into new leaves, roots and other organic matter. When some of this carbon is <a href="https://www.nature.com/articles/s43017-021-00224-1">stored long-term</a> in deep sediments, it can help battle rising CO₂ levels in our atmosphere.</p>
<p>The coastal net greenhouse gas uptake should not be confused with carbon storage. Only part of the coastal greenhouse gas uptake is stored long-term in coastal sediments, while another part is transported to the ocean where it might be stored or released back to the atmosphere.</p>
<h2>Not all coasts are the same</h2>
<p>Africa and Australia have large swathes of sandy coastline and coastal wetlands. By contrast, Europe and Russia’s cold coastline lacks mangroves or tropical coastal wetlands. These differences drive the changes we found in how different coasts take up or emit greenhouse gases. </p>
<p>The strongest coastal greenhouse gas sink is Southeast Asia, because of its extensive and productive tropical mangrove forests and seagrasses which soak up large amounts of CO₂. North America’s coast is another excellent sink for greenhouse gases, with its salt marshes, mangroves, seagrasses – and Canada’s fjords, glacier-made valleys filled with seawater. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/527390/original/file-20230521-21-u8nzo8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="wetlands coast" src="https://images.theconversation.com/files/527390/original/file-20230521-21-u8nzo8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527390/original/file-20230521-21-u8nzo8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527390/original/file-20230521-21-u8nzo8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527390/original/file-20230521-21-u8nzo8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527390/original/file-20230521-21-u8nzo8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527390/original/file-20230521-21-u8nzo8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527390/original/file-20230521-21-u8nzo8.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">Coastal wetlands like this one on Assateague Island in America are excellent carbon sinks - but can emit methane.</span>
<span class="attribution"><span class="source">Sara Cottle/Unsplash</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>While Australia and New Zealand have long stretches of coastal wetlands soaking up CO₂, this is offset by a large number of estuaries, many of which are a source of greenhouse gases produced by decaying organic matter. </p>
<p>Coasts in Europe and Russia actually release more greenhouse gases than they absorb. Their many polluted tidal estuaries release greenhouse gases, but the colder climate means this region has fewer coastal wetlands to soak these gases back up. </p>
<p>But across the three main greenhouse gases, eight out of the ten world coastal regions are a net greenhouse gas sink. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/527388/original/file-20230521-184046-lvwn0g.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="figure" src="https://images.theconversation.com/files/527388/original/file-20230521-184046-lvwn0g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527388/original/file-20230521-184046-lvwn0g.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=381&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527388/original/file-20230521-184046-lvwn0g.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=381&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527388/original/file-20230521-184046-lvwn0g.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=381&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527388/original/file-20230521-184046-lvwn0g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=479&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527388/original/file-20230521-184046-lvwn0g.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=479&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527388/original/file-20230521-184046-lvwn0g.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=479&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This figure shows the net fluxes of carbon dioxide, methane and nitrous oxide in estuaries (yellow arrows), coastal vegetation (peach arrows) and combined (red arrows) in 10 regions around the world. Southeast Asia (9), North America (1) and Africa (4) are strong coastal greenhouse gas sinks. South America (2), Australasia (10), and West Asia (6) are moderate sinks, while East Asia (7) and South Asia (8) are weak sinks. Europe (3) and Russia (5) are weak coastal sources of greenhouse gases.</span>
<span class="attribution"><a class="source" href="https://www.nature.com/articles/s41558-023-01682-9">Figure from Rosentreter et al. (2023) Nature Climate Change</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Some coasts soak up greenhouse gases while others emit more</h2>
<p>The world’s coastal ecosystems are enormously diverse, ranging from tropical lagoons to polar fjords to coastal mangrove forests to underwater seagrass meadows. This sheer variety means they differ greatly in how they take up or release greenhouse gases.</p>
<p>For example, we show that fjords around the world take up around 40% of CO₂ that would otherwise be released from tidal systems, deltas and lagoons. Most (86%) of this important CO₂ uptake by fjords comes from the North America region. </p>
<p>By contrast, salt marshes and mangroves are home to trillions of microorganisms which live in deep, oxygen-free sediments, eating dead organic matter and emitting methane and nitrous oxide. Some of these gases reach the atmosphere, making many coastal waters a source of methane and nitrous oxide.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/527391/original/file-20230521-146674-yvgomr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="coastal ecosystem" src="https://images.theconversation.com/files/527391/original/file-20230521-146674-yvgomr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527391/original/file-20230521-146674-yvgomr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527391/original/file-20230521-146674-yvgomr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527391/original/file-20230521-146674-yvgomr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527391/original/file-20230521-146674-yvgomr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527391/original/file-20230521-146674-yvgomr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527391/original/file-20230521-146674-yvgomr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some coastal ecosystems take up large amounts of carbon dioxide.</span>
<span class="attribution"><span class="source">Unsplash</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Coastal wetlands release more than three times more methane than all estuaries in the world. But coastal wetlands, also called coastal “blue carbon” wetlands, can be strong sinks of CO₂ and some also take up nitrous oxide. On balance, these coastal ecosystems become a net greenhouse sink when we consider the net effect of these three most important greenhouse gases. </p>
<p>What does the big picture look like? Globally, our research shows our coasts’ ability to take up CO₂ is offset between 9% and 20% by coastal methane and nitrous oxide emissions. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/half-of-global-methane-emissions-come-from-aquatic-ecosystems-much-of-this-is-human-made-156960">Half of global methane emissions come from aquatic ecosystems – much of this is human-made</a>
</strong>
</em>
</p>
<hr>
<h2>Why is this knowledge important?</h2>
<p>If we understand how our coastal ecosystems take up or emit greenhouse gases, we can target the most crucial ecosystems for preservation or restoration. </p>
<p>That’s why many researchers are interested in blue carbon as a way to boost long-term carbon storage. By protecting and restoring mangroves and salt marshes in nations rich in blue carbon, such as Indonesia, we can expand their ability to take these gases back out of the atmosphere and ultimately store some of the carbon long-term in their sediments. </p>
<p>And by reducing nutrient overload, organic matter and wastewater flows into our coastal waterways, we can cut the greenhouse gases emitted by polluted estuaries. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/floods-of-nutrients-from-fertilisers-and-wastewater-trash-our-rivers-could-offsetting-help-203235">Floods of nutrients from fertilisers and wastewater trash our rivers. Could offsetting help?</a>
</strong>
</em>
</p>
<hr>
<p>We shouldn’t just see our coastal ecosystems as a boon to carbon credit markets. They have much more to offer, including many valuable ecosystem services. Our coasts protect our shorelines from severe weather and tides. They are a nursery for many fish and plants. And they’re vital to us as a place to be in nature.</p>
<p>Protecting our coasts is good for us, for nature and for the earth system as it plunges into the climate crisis.</p>
<p><em>Acknowledgements: We would like to thank our international team of scientists and the <a href="https://www.globalcarbonproject.org/reccap/index.htm">Global Carbon Project</a> for initiating this research.</em></p><img src="https://counter.theconversation.com/content/205473/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Judith Rosentreter receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Bradley Eyre receives funding from the Australian Research Council.</span></em></p>Mangroves and salt marshes pump out methane – but soak up carbon dioxide. Overall, the world’s coasts are a net greenhouse sink – and we must preserve themJudith Rosentreter, Senior research fellow, Southern Cross UniversityBradley Eyre, Professor of Biogeochemistry, Director of the Centre for Coastal Biogeochemistry, Southern Cross UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1972062023-03-31T14:56:56Z2023-03-31T14:56:56ZThe UK’s first climate refugees: why more defences may not save this village from rising sea levels<figure><img src="https://images.theconversation.com/files/514912/original/file-20230313-22-tojj56.jpg?ixlib=rb-1.1.0&rect=46%2C0%2C5175%2C3431&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A view of Fairbourne from above, showing the Mawddach estuary and the mountains of Eryri in the background. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/view-high-vantage-point-over-fairbourne-1475179817">Wozzie/Shutterstock</a></span></figcaption></figure><p>The impact of rising sea levels on our coastlines can be profound. A natural shoreline can respond to sea level rise and coastal erosion, provided the rise isn’t too rapid. </p>
<p>Given enough time, flora and fauna may have a chance to adapt. But a coastal area which has been heavily developed will respond differently, sometimes with catastrophic impacts on both people and nature. </p>
<p>Fairbourne is a small village on the west coast of Wales and is the first place in the UK to have been assigned the long-term policy of “<a href="https://www.gov.wales/sites/default/files/publications/2019-12/fairbourne-coastal-risk-management-learning-project.pdf">no active intervention</a>” regarding its coastal defences. That is when a decision is made not to invest in providing or maintaining sea defences. </p>
<p>This has led to Fairbourne’s inhabitants being described as “<a href="https://www.bbc.com/future/article/20220506-the-uk-climate-refugees-who-wont-leave">the UK’s first climate change refugees</a>” by news media. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/coastal-erosion-is-unstoppable-so-how-do-we-live-with-it-186365">Coastal erosion is unstoppable – so how do we live with it?</a>
</strong>
</em>
</p>
<hr>
<p>In the UK, regional <a href="https://naturalresources.wales/flooding/managing-flood-risk/shoreline-management-plans/?lang=en">shoreline management plans</a> (SMPs) are developed for managing coastlines from flood and erosion risk. SMPs consider the potential risks and select from a range of options, consisting of building new sea defences, through to the aforementioned “no active intervention”.</p>
<p>In Fairbourne’s case, the SMP suggests it will neither be safe nor sustainable to remain in the village by around 2054. The intention is for the authorities to monitor and maintain the existing coastal defences in the short and medium term. </p>
<p>Ultimately, the village may be decommissioned, although details are scant on what that means. It remains a <a href="https://www.sciencedirect.com/science/article/pii/S0962629823000173">contentious</a> issue and the <a href="https://www.dailypost.co.uk/news/north-wales-news/artificial-reef-tidal-barrage-plan-26091970">community</a> continues to fight for increased support from government organisations. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1620131189305778176"}"></div></p>
<p>At the turn of the 20th century, Fairbourne was just a cluster of houses on the Gwynedd coast at the mouth of the Mawddach estuary. Over the past 100 years, the village has expanded to around 460 properties. It has around 700 inhabitants and is popular with tourists. </p>
<p>Fairbourne is built on a low-lying floodplain. The village lies between cliffs and a natural gravel barrier which houses a sea wall, and is at risk from both coastal and river flooding. As the sea level around the Welsh coast rises, the village is at increased risk from coastal flooding.</p>
<h2>Sea level rise drivers</h2>
<p>There are two main factors which drive global mean sea level rise, both related to climate change. First, the addition of freshwater to our oceans from melting glaciers and ice sheets. And second, the expansion of ocean water as it warms up, which is a consequence of higher atmospheric temperatures. </p>
<p>The global mean sea level <a href="https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-9/">rose higher</a> in the 20th century than in any other century during the last 3,000 years. The rate of global mean sea level rise in 2021 was the <a href="https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-9/">highest ever recorded</a>. Uncertainty remains in the projections of future sea level rise but the latest <a href="https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-9/">estimate</a> is that a global rise of up to approximately 1 metre by 2100 is possible. </p>
<figure class="align-center ">
<img alt="A series of concrete cubes line a pebble beach." src="https://images.theconversation.com/files/516343/original/file-20230320-905-aewu6t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516343/original/file-20230320-905-aewu6t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516343/original/file-20230320-905-aewu6t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516343/original/file-20230320-905-aewu6t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516343/original/file-20230320-905-aewu6t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516343/original/file-20230320-905-aewu6t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516343/original/file-20230320-905-aewu6t.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">The gravel barrier between Fairbourne and the sea is dotted with second world war concrete defence blocks.</span>
<span class="attribution"><a class="source" href="https://www.geograph.org.uk/photo/4973146">Mike Searle/Geograph</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The response of a natural gravel barrier coastline to sea level rise is mainly controlled by the amount of nearby sediment and the rate at which the sea level is rising along that section of coast. </p>
<p>Where there is available mobile sediment, a barrier will move towards the land under rising sea levels. This process is called “roll-over”, as sediments are pushed up and over the crest of the barrier towards the land. </p>
<p>However, if the barrier is prevented from moving or if the sea level rises rapidly, more significant structural changes can happen. First, the barrier tends to get steeper, which then promotes more energetic wave breaking. </p>
<p>In time, the barrier crest becomes vulnerable which can lead to it being breached. In the case of Fairbourne, which is behind such a barrier, a breach could result in the village being flooded.</p>
<p>Second, the barrier needs time to adapt to changes in sea level. When the level of the sea rises rapidly, the barrier cannot evolve quickly enough to keep up. </p>
<figure class="align-center ">
<img alt="A small blue miniature train travels along a track in front of houses." src="https://images.theconversation.com/files/514963/original/file-20230313-17-ri2btt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/514963/original/file-20230313-17-ri2btt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/514963/original/file-20230313-17-ri2btt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/514963/original/file-20230313-17-ri2btt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/514963/original/file-20230313-17-ri2btt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/514963/original/file-20230313-17-ri2btt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/514963/original/file-20230313-17-ri2btt.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">
<figcaption>
<span class="caption">The Fairbourne Railway is a miniature railway which runs along the coastline.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/16801915@N06/28608309993">Reading Tom/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In Fairbourne, <a href="https://www.tandfonline.com/doi/abs/10.1080/02697459.2019.1696145">these factors combine</a> to increase the flood risk to the community. The sediment supply to the gravel barrier is limited. To compound the issue, as the sea level rises, the water becomes deeper which leads to less available wave energy for pushing sediments onshore. </p>
<p>The potential for Fairbourne’s seaward barrier to shift towards the land is limited by the lack of space. The barrier is somewhat trapped between the hard rock of the cliffs and the nearby Afon Mawddach. </p>
<p>What’s more, the existing seawall fixes the crest of the barrier in place and therefore increases its vulnerability. Meanwhile, the sea level continues to rise.</p>
<h2>Adaptation</h2>
<p>Physical and environmental factors aside, sea level rise is a complicated socio-economic issue. Regardless of the financial cost, building coastal defences is not always the best method of adaptation. </p>
<p>The UK’s SMPs provide a strategic approach to coastal management and defence. However, retreating from the coastline, disbanding communities, abandoning homes and decommissioning villages such as Fairbourne really is the ultimate form of adaptation and so requires careful consideration. </p>
<p>Given <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2013EF000188">around 10%</a> of the world’s population live in coastal areas fewer than 10 metres above sea level, this is a topic we’re likely to be discussing a lot more in years to come.</p><img src="https://counter.theconversation.com/content/197206/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sophie Ward received/receives funding from: NERC, European Regional Development Fund, Convex Seascape Survey</span></em></p><p class="fine-print"><em><span>Martin Austin receives funding from: EPSRC, NERC. </span></em></p>Fairbourne on the west coast of Wales is at risk from both rising sea levels and river flooding.Sophie Ward, Research Fellow in Physical Oceanography, Bangor UniversityMartin Austin, Senior Lecturer in Coastal Dynamics, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1863652022-10-12T15:49:24Z2022-10-12T15:49:24ZCoastal erosion is unstoppable – so how do we live with it?<figure><img src="https://images.theconversation.com/files/489341/original/file-20221012-26-hll9p1.JPG?ixlib=rb-1.1.0&rect=0%2C0%2C3888%2C2590&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Sophie Day</span>, <span class="license">Author provided</span></span></figcaption></figure><p>A record storm surge in 1953 devastated much of eastern England’s coast, prompting prolific investment in concrete sea walls, wooden groynes and other engineered structures designed to protect the coastline from erosion. These measures brought a reassuring sense of permanence for people in previously risky locations. Houses atop sandy cliffs and tucked behind or among sand dunes went from being holiday homes to permanent residences, and new homes were built nearby. </p>
<p>But decades later, the east coast and other parts of England are still eroding – rapidly in some places – despite efforts to hold the coastline in place. </p>
<p>England has some of the <a href="https://www.gov.uk/government/publications/national-flood-and-coastal-erosion-risk-management-strategy-for-england--2">fastest eroding coastline</a> in Europe, particularly along the Norfolk and Yorkshire coasts. Historical records show that England’s soft and sandy east coast has always been subject to retreat. The numerous <a href="https://www.edp24.co.uk/news/weird-nofolk-ghost-bells-haunted-eccles-1562000">lost villages</a> beneath the North Sea are testament to this. </p>
<figure class="align-center ">
<img alt="A beach lined with wooden groynes and other structures." src="https://images.theconversation.com/files/489345/original/file-20221012-14-ql1ktx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/489345/original/file-20221012-14-ql1ktx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489345/original/file-20221012-14-ql1ktx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489345/original/file-20221012-14-ql1ktx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489345/original/file-20221012-14-ql1ktx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489345/original/file-20221012-14-ql1ktx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489345/original/file-20221012-14-ql1ktx.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">Sea walls and other structures cannot hold the coastline together forever.</span>
<span class="attribution"><span class="source">Sophie Day</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Back in 2018 the <a href="https://www.theccc.org.uk/publication/managing-the-coast-in-a-changing-climate/">Committee on Climate Change</a>, which advises the UK government, calculated that around 9,000 properties in England are located in areas likely to be lost to coastal erosion by 2025. This number is projected to increase 15-fold by the end of the century, disrupting whole communities as more buildings, roads and farmland inevitably slip into the danger zone.</p>
<h2>Unstoppable – and necessary?</h2>
<p>A growing body of research warns that the speed of coastal erosion will be compounded by sea-level rise and other effects of climate change, such as more extreme storms and prolonged wet weather, as waterlogged soils increase the likelihood of sandy cliffs collapsing. Rates of erosion can be roughly but not precisely estimated, due to the complexity of coastal systems and uncertainty regarding how the effects of climate change will manifest. </p>
<figure class="align-center ">
<img alt="A paved road ending in a sheer cliff edge." src="https://images.theconversation.com/files/488482/original/file-20221006-12-foygpz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/488482/original/file-20221006-12-foygpz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/488482/original/file-20221006-12-foygpz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/488482/original/file-20221006-12-foygpz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/488482/original/file-20221006-12-foygpz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/488482/original/file-20221006-12-foygpz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/488482/original/file-20221006-12-foygpz.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">
<figcaption>
<span class="caption">Life in an eroding community can be unpredictable.</span>
<span class="attribution"><span class="source">Sophie Day</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Since the early 1990s, scientists have collected huge amounts of data in order to understand how the wind, waves, tides and storms shape coastlines. The evidence indicates that it is not possible or prudent to stop or delay coastal erosion forever and that in some places, it <a href="https://doi.org/10.1007/s10584-008-9532-8">may even be necessary</a>. </p>
<p>This is because when soft cliffs such as those along the east of England retreat, they release a lot of sand which is deposited on nearby beaches, making them higher and wider. High and wide beaches absorb the energy of waves, giving some protection to cliffs, dunes and sea walls from coastal erosion and flooding. </p>
<p>The chief executive of the Environment Agency for England recently said it is inevitable that at some point communities will have to <a href="https://www.gov.uk/government/news/environment-agency-sets-out-roadmap-for-more-flood-and-climate-resilient-nation">move back from the coast</a>. So what does this mean for people who live in places where coastal erosion is accelerating, or where it can no longer be stopped?</p>
<p>At Happisburgh in north Norfolk for example, a section of old and damaged sea defences had to be removed in the 1990s to avert dangerous collapse. Rapid erosion of the beach and cliffs since the early 2000s has meant homes in this village being steadily demolished as the coastline retreats. As yet there are no arrangements to compensate people here, or other government policies to help them adapt.</p>
<figure class="align-center ">
<img alt="A series of collapsed houses along a sandy outcrop." src="https://images.theconversation.com/files/488485/original/file-20221006-19-rx1fs1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/488485/original/file-20221006-19-rx1fs1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/488485/original/file-20221006-19-rx1fs1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/488485/original/file-20221006-19-rx1fs1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/488485/original/file-20221006-19-rx1fs1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/488485/original/file-20221006-19-rx1fs1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/488485/original/file-20221006-19-rx1fs1.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">Uprooted.</span>
<span class="attribution"><span class="source">Sophie Day</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Living with coastal erosion</h2>
<p>It is important to be realistic: homes, roads and other things which knit some coastal communities together will need to be relocated inland away from danger – and soon. But doing this is far from simple, and will certainly be <a href="https://www.pnas.org/doi/full/10.1073/pnas.1222469111">costly</a>. </p>
<p>Ideally, the kind of investment which erected coastal defences in the aftermath of the 1953 storm surge would be mobilised today to help these places move. This is a pressing issue – letting crisis and despair characterise life for coastal communities on the edge is unsustainable and unfair.</p>
<p>Slowly, things are changing. A network of coastal communities, local authority officers and politicians, academics and others have worked since the early 2000s to argue for what is needed to cope with and prepare for coastal erosion around England and Wales. Now, a new <a href="https://engageenvironmentagency.uk.engagementhq.com/hub-page/fcrmfund">pulse of government funding</a> could test these ideas so that in future, no community feels abandoned to the sea. </p>
<figure class="align-center ">
<img alt="An abandoned building behind a metal fence." src="https://images.theconversation.com/files/488483/original/file-20221006-12-h8kp16.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/488483/original/file-20221006-12-h8kp16.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/488483/original/file-20221006-12-h8kp16.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/488483/original/file-20221006-12-h8kp16.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/488483/original/file-20221006-12-h8kp16.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/488483/original/file-20221006-12-h8kp16.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/488483/original/file-20221006-12-h8kp16.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">
<figcaption>
<span class="caption">Eroding coastal communities need reassurance and support.</span>
<span class="attribution"><span class="source">Sophie Day</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Part of this work will be to begin the transition in eroding towns and villages on England’s east coast from a state of crisis to one in which people can begin to live feeling safe and confident. It must be systematically worked out how communities can move away from risky areas while maintaining homes, utilities and services, as well as preserving local heritage, culture and each place’s unique character. </p>
<p>As academics working alongside government agencies, our next challenge will be ensuring these time-limited projects translate into robust national policy and funding. Coastal erosion cannot be stopped, so we must help everyone relearn how to live with it.</p>
<hr>
<figure class="align-right ">
<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">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 10,000+ readers who’ve subscribed so far.</a></em></p>
<hr><img src="https://counter.theconversation.com/content/186365/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sophie Day receives funding from North Norfolk District Council (part of Coastal Partnership East) to support a part-time research secondment. She is also affiliated with the Tyndall Centre for Climate Change Research. </span></em></p><p class="fine-print"><em><span>Robert James Nicholls is director of the Tyndall Centre for Climate Change Research at the University of East Anglia, He receives funding from the European Union's Horizon 2020 research and innovation programme under the PROTECT project on sea-level rise (grant agreement 869304), the CoClioCo project on coastal climate services (grant agreement 101003598) and the REST-COAST project on coastal restoration (grant agreement 101037097). He also receives funding under the EPSRC-funded Infrastructure for Port And Coastal cities and Towns network (iPACT) (EP/W033933/1). He has contributed to research led by JBA funded by the Environment Agency to develop metrics concerning flood and coastal change resilience. </span></em></p>Moving entire communities threatened by rising seas isn’t as far-fetched as it sounds.Sophie A. Day, Senior Research Associate in Environmental Sciences, University of East AngliaRobert James Nicholls, Professor of Climate Adaptation, University of East AngliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1842142022-06-16T12:24:54Z2022-06-16T12:24:54ZCoastal gentrification in Puerto Rico is displacing people and damaging mangroves and wetlands<figure><img src="https://images.theconversation.com/files/469067/original/file-20220615-11-lv96u2.jpg?ixlib=rb-1.1.0&rect=10%2C0%2C1152%2C763&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Tourism-driven development is threatening one of Puerto Rico's greatest draws: its rural coastlines.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/aJeMia">R9 Studios FL/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>As world travel rebounds after two years of COVID-19 shutdowns and restrictions, marketers and the media are promoting Puerto Rico as an accessible <a href="https://www.cnn.com/travel/article/puerto-rico-travel-2022/index.html">hot spot destination</a> for continental U.S. travelers. The commonwealth <a href="https://newsismybusiness.com/puerto-rico-had-record-year-for-tourism-in-21-discover-puerto-rico-says/">set a visitor record in 2021</a>, and it is <a href="https://www.travelagewest.com/Travel/Caribbean/puerto-rico-travel-2022">expanding tourism-related development</a> to continue wooing travelers away from more exotic destinations. </p>
<p>Tourism income is central to Puerto Rico’s economy, especially in the wake of <a href="https://www.businessinsider.com/puerto-rico-tourism-recovery-after-hurricane-maria-2020-6">heavy damage from Hurricane Maria in 2017</a>. But it comes at a cost: destruction of mangroves, wetlands and other coastal areas. Puerto Rico is no stranger to resort construction, but now widespread small-scale projects to meet demand for <a href="https://caribbeanbusiness.com/there-are-over-10000-airbnb-listed-properties-in-puerto-rico/">rentals on platforms like Airbnb</a> are adding to concerns about <a href="https://doi.org/10.1016/j.annals.2019.102845">coastal gentrification</a> and <a href="https://doi.org/10.1080/13604813.2018.1548819">touristification</a>. </p>
<p>As scholars who study <a href="https://scholar.google.com/citations?user=THbsmg4AAAAJ&hl=en">anthropology</a> and <a href="https://scholar.google.com/citations?user=1nA5J-QAAAAJ&hl=en">coastal communities</a>, we believe it is important to understand what Puerto Rico is losing in the quest for ever-increasing tourist business. For the <a href="https://theconversation.com/what-rural-coastal-puerto-ricans-can-teach-us-about-thriving-in-times-of-crisis-76119">rural coastal communities</a> where we do our research, habitat is tied to residents’ cultural identity and economic well-being.</p>
<p>For the last two decades, we have documented how many rural Puerto Ricans’ lives are inextricably linked to <a href="https://doi.org/10.3998/jar.0521004.0071.201">coastal forests and wetland habitats</a>. These communities often are poor, neglected by the state and disproportionately affected by <a href="https://theconversation.com/in-puerto-rico-environmental-injustice-and-racism-inflame-protests-over-coal-ash-69763">pollution and noxious industries</a>. Decisions about the future of the coast too often are made without accounting for human impacts.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Vxk64GEZ7g0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">By law, all beaches on Puerto Rico are public, but many people say construction threatens the island’s natural resources.</span></figcaption>
</figure>
<h2>Once-scorned areas are now in demand</h2>
<p>Estuaries and coastal forests are some of Earth’s most <a href="https://doi.org/10.3389/fmars.2018.00376">biodiverse and productive ecosystems</a>. Millions of people rely on <a href="https://www.sarasota.wateratlas.usf.edu/upload/documents/ImportanceOfMangrovesToPeople-UNEP-2014.pdf">mangroves and coastal wetlands</a> to make a living. </p>
<p>Around the world, these areas are <a href="https://doi.org/10.3389/fevo.2020.00144">under stress</a> from climate change, <a href="https://globalvoices.org/2021/05/11/destruction-of-coastal-forest-for-a-major-tourism-project-raises-questions-about-jamaicas-climate-change-posture/">tourism</a> and luxury residential development. But these zones weren’t always prized so highly.</p>
<p>In Puerto Rico and elsewhere in the Americas, <a href="https://www.wiley.com/en-us/Wetlands%2C+5th+Edition-p-9781118676820">wetlands</a> historically were seen as undesirable and even dangerous places to live and work. They often were settled by the poor and dispossessed, most notably <a href="https://www.aaihs.org/from-extractive-agriculture-to-industrial-waste-periphery-life-in-a-black-puerto-rican-ecology/">Afro-descendant people</a> and Indigenous communities, who made livings <a href="https://www.jstor.org/stable/24706389">fishing, foraging, harvesting coconuts, cutting wood and making charcoal</a>.</p>
<p>In the early 20th century, however, tropical coasts started attracting attention from the global leisure class. In 1919, the Vanderbilt Hotel opened in San Juan, followed in 1949 by the massive Caribe Hilton resort – the <a href="https://rowman.com/ISBN/9780739189184/Imaging-The-Great-Puerto-Rican-Family-Framing-Nation-Race-and-Gender-during-the-American-Century">first Hilton hotel outside the continental U.S.</a>, built in partnership with the Puerto Rican government. Many more hotels followed, along with casinos and golf courses. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1458165063324352516"}"></div></p>
<p>Today, Puerto Rico’s rural coastal communities have to <a href="http://dx.doi.org/10.36019/9780813537528-005">compete for space and resources</a> against tourism development, gentrification, urbanization, industry and conservation. Often these uses are not compatible with local lifestyles. </p>
<p>For example, people from communities near mangrove forests, like Las Mareas in southern Puerto Rico, are no longer permitted to <a href="https://drna.pr.gov/wp-content/uploads/2016/12/SAP-2016-FINAL-9-15-2016-rev-ETI.compressed.pdf">harvest small amounts of mangrove wood</a> to build traditional fishing boats. At the same time, they see wealthy residents and developers <a href="https://apnews.com/article/climate-caribbean-puerto-rico-mangroves-36e4e66f520e241f315fa4a1d8558ac1">destroying entire tracts of mangrove forest</a> with impunity. Some coastal communities are starting to push back.</p>
<h2>Beaches are for the people</h2>
<p>In March 2022, <a href="https://www.instagram.com/eliezermolinapr/?hl=en">Eliezer Molina</a>, an environmental activist, engineer and 2020 gubernatorial candidate, posted <a href="https://www.youtube.com/watch?v=se4HdAJ0K20">an exposé on YouTube</a> of the illegal cutting and filling of a mangrove shoreline in the <a href="https://periodismoinvestigativo.com/2022/03/local-and-federal-negligence-enables-environmental-crime-in-the-bahia-jobos-reserve-in-salinas/">Las Mareas neighborhood</a> in Salinas’ Jobos Bay. As Puerto Rico’s second-largest estuary and only <a href="https://coast.noaa.gov/nerrs/reserves/jobos-bay.html">Federal Estuarine Reserve</a>, the bay is an <a href="https://doi.org/10.1016/j.aquabot.2007.12.007">important and sensitive habitat</a> for birds, turtles and manatees, and a nursery for many types of fish.</p>
<p>Wealthy Puerto Ricans <a href="https://www.latimes.com/world-nation/story/2022-05-06/illegal-building-making-puerto-rico-more-vulnerable-to-climate-change-critics-warn">clandestinely developed this waterfront site</a> for weekend homes. Residents of Las Mareas had been alerting local authorities for well over a decade about destruction of the mangroves, to no avail. Federal authorities and Puerto Rico’s Justice Department are now <a href="https://www.elnuevodia.com/noticias/locales/notas/federales-buscan-informacion-en-bahia-de-jobos-en-salinas/">conducting a criminal investigation</a> of the illegal construction.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469069/original/file-20220615-11810-84txpr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Beach homes under construction in a forested area." src="https://images.theconversation.com/files/469069/original/file-20220615-11810-84txpr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469069/original/file-20220615-11810-84txpr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469069/original/file-20220615-11810-84txpr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469069/original/file-20220615-11810-84txpr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469069/original/file-20220615-11810-84txpr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469069/original/file-20220615-11810-84txpr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469069/original/file-20220615-11810-84txpr.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"></a>
<figcaption>
<span class="caption">Construction at the Jobos Bay National Estuarine Research Reserve, in Salinas, Puerto Rico, May 3, 2022. Puerto Rico’s Justice Department has launched a criminal investigation into destruction in the ecological reserve.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/ClimateChangePuertoRicoIllegalConstruction/0a093eb19f004740a690fcacbc54834b/photo">AP Photo/Carlos Giusti</a></span>
</figcaption>
</figure>
<p>This case led to widespread public outrage about <a href="https://www.liberationnews.org/the-fight-against-privatization-of-beaches-in-puerto-rico/">similar instances</a> around the archipelago. Puerto Ricans are condemning local government agencies <a href="https://www.instagram.com/biancagraulau/?hl=en">online</a> and <a href="https://www.nbcnews.com/now/video/puerto-ricans-protest-privatization-of-public-beaches-140998725522">in person</a> for what they describe as incompetence, corruption and a lack of monitoring and oversight. </p>
<p>One hot-button issue is <a href="https://gizmodo.com/puerto-rico-rincon-beach-protests-1848747800">privatization and destruction</a> of the <a href="https://ayudalegalpr.org/resource/zona-maritimo-terrestre">Zona Marítimo Terrestre</a>, or Terrestrial Maritime Zone. This area is legally defined as “Puerto Rico’s coastal space that is bordered by the sea’s ebb and flow” – that is, between the low and high tide or up to the highest point of the surf zone. It includes beaches, mangroves and other coastal wetlands, and is publicly owned.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/469099/original/file-20220615-10494-phcn3k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Protest poster in Spanish on a wall in a small local market" src="https://images.theconversation.com/files/469099/original/file-20220615-10494-phcn3k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/469099/original/file-20220615-10494-phcn3k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469099/original/file-20220615-10494-phcn3k.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469099/original/file-20220615-10494-phcn3k.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469099/original/file-20220615-10494-phcn3k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469099/original/file-20220615-10494-phcn3k.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469099/original/file-20220615-10494-phcn3k.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"></a>
<figcaption>
<span class="caption">A poster in a seafood market in the village of Pozuelo, Guayama, reads ‘Stop the destruction and privatization of the coasts.’</span>
<span class="attribution"><span class="source">Hilda Llorens</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Activists are urging Gov. Pedro Pierluisi to declare a comprehensive moratorium on all coastal construction, a demand the governor calls “<a href="https://weather.com/photos/news/2022-05-10-illegal-construction-puerto-rico-mangrove">excessive</a>.” A popular protest slogan, “<a href="https://www.youtube.com/watch?v=nJB_m66pn14">Las playas son del pueblo!</a>” (“Beaches belong to the people”), aptly summarizes popular feeling. </p>
<h2>Overlooked value</h2>
<p>Coastal development generates a lot of money in Puerto Rico, but what is gained by conserving these areas for use by local communities? In research that we carried out in <a href="https://app.box.com/s/wdlgd9tg1p0e7v4i99jp0sre40dej59i">2010-2013</a> and <a href="https://app.box.com/s/qt3c2cf4f7hlo2kpi7qhq6l88ntbtms8">2016-2021</a>, we found that coastal resources provide <a href="https://doi.org/10.1007/s40152-019-00144-3">many benefits</a> for local residents that are not easily replaced. </p>
<p>Our results show that about one-third of households in these communities rely on coastal goods for at least part of their income, while more than two-thirds rely on them as food sources. Local harvesters supply family-owned seafood restaurants with foods such as land crabs, helping to attract economic activity to the coast. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469098/original/file-20220615-11810-nettdf.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/469098/original/file-20220615-11810-nettdf.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469098/original/file-20220615-11810-nettdf.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469098/original/file-20220615-11810-nettdf.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469098/original/file-20220615-11810-nettdf.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469098/original/file-20220615-11810-nettdf.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469098/original/file-20220615-11810-nettdf.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469098/original/file-20220615-11810-nettdf.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"></a>
<figcaption>
<span class="caption">Religious-themed murals commonly illustrate the importance of productive coasts for seaside Puerto Rican communities.</span>
<span class="attribution"><span class="source">Hilda Llorens</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We also found that residents <a href="http://dx.doi.org/10.1353/crb.2021.0010">rely more heavily</a> on local coastal foods during times of severe economic stress, such as recessions and natural disasters. In the aftermath of Hurricanes Irma and María, for example, many residents in the southern towns of Salinas and Santa Isabel harvested unusually abundant land crabs when it was hard to find other foods. Some even saw this abundance as <a href="https://muse.jhu.edu/article/800801">divine restitution for the suffering the storm inflicted on them</a>. </p>
<p>Local economies in these communities consist mainly of small-scale, community-based transactions that include gifting, bartering and selling. Their social and economic impacts often go unnoticed and are underestimated in official economic accounts, so they aren’t reflected in decisions about coastal development. But as our work shows, coastal ecosystems are <a href="https://doi.org/10.1007/s40152-019-00144-3">ecologically, economically and socially productive places</a>.</p>
<p>In 2010, we asked people living along Puerto Rico’s southern coast: “What would your community look like without access to the mangrove and its bounties?” The owner of a family restaurant, replied: “The answer is easy. Without access to coastal resources, this community would be dead and sad.”</p><img src="https://counter.theconversation.com/content/184214/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Carlos G. García-Quijano has received funding from the National Science Foundation and the National Oceanic and Atmospheric Administration-Sea Grant.</span></em></p><p class="fine-print"><em><span>Hilda Lloréns has received funding from the National Science Foundation, the National Oceanic and Atmospheric Administration-Sea Grant, and the University of Rhode Island's Arts & Sciences Dean's Opportunity Fund.</span></em></p>Puerto Rico’s tourism industry is booming as nations lift COVID-19 travel restrictions, but development is displacing people who have lived along its coastlines for years.Carlos G. García-Quijano, Professor of Anthropology and Marine Affairs, University of Rhode IslandHilda Lloréns, Associate Professor, Anthropology & Marine Affairs, University of Rhode IslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1798122022-04-13T12:13:16Z2022-04-13T12:13:16ZRedwood trees have two types of leaves, scientists find – a trait that could help them survive in a changing climate<figure><img src="https://images.theconversation.com/files/457498/original/file-20220411-11-h2ic9b.jpg?ixlib=rb-1.1.0&rect=16%2C0%2C5542%2C3709&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Coastal redwoods in Felton, California.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/coastal-redwoods-stand-in-the-henry-cowell-redwoods-state-news-photo/915647562">Carolyn Van Houten/The Washington Post via Getty Images</a></span></figcaption></figure><p>Coast redwoods are amazing trees that scientists have studied for generations. We know they are <a href="https://doi.org/10.1038/nature02417">the tallest living trees</a> and have survived for millennia, <a href="https://academic.oup.com/jof/article-abstract/29/6/939/4719848">resisting fire</a> and <a href="https://nzjforestryscience.springeropen.com/articles/10.1186/s40490-014-0017-4">pests</a>. Because redwoods are long-lived, large and decay-resistant, the forests they dominate store <a href="https://doi.org/10.1016/j.foreco.2016.05.018">more above-ground mass, and thus presumably more carbon</a>, than any other ecosystem on Earth. </p>
<p>Nonetheless, while working on a recently published study, colleagues at the <a href="https://scholar.google.com/citations?user=qeqqJqwAAAAJ">University of California</a>, <a href="https://scholar.google.com/citations?user=S3LivCgAAAAJ&hl=es">Davis</a>, and <a href="https://scholar.google.com/citations?user=5dqacuQAAAAJ&hl=en">Cal Poly</a> <a href="https://kerhoulasforestlab.weebly.com/">Humboldt</a> and <a href="https://scholar.google.com/citations?hl=en&user=Qv4DpXAAAAAJ">I</a> learned a secret that had been sitting right under our noses. </p>
<p>Redwoods, it turns out, have two types of leaves that look different and perform very different tasks. This previously unknown feature helps the trees adapt to both wet and dry conditions – an ability that could be key to their survival in a changing climate.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/-swLTsWXPII?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Redwoods can live for more than 2,000 years and grow to more than 350 feet tall.</span></figcaption>
</figure>
<h2>Just enough water</h2>
<p>Wherever trees grow, sooner or later their leaves get wet. For trees in wet environments, this can be a problem if films of water <a href="https://doi.org/10.1111/j.1365-3040.1995.tb00377.x">cover their stomata</a>. These tiny pores allow carbon dioxide to enter leaves so the tree can combine it with water to make plant tissue through <a href="https://www.usda.gov/media/blog/2015/03/17/power-one-tree-very-air-we-breathe">photosynthesis</a>. Many trees that are common to wet forests have leaves with adaptations that <a href="https://doi.org/10.1073/pnas.95.24.14256">prevent these water films from forming</a>. </p>
<p>In contrast, trees growing in dry environments take advantage of brief bouts of leaf wetness to <a href="https://doi.org/10.1111/nph.15307">take up valuable water</a> directly across the surfaces of their leaves, <a href="http://dx.doi.org/10.1111/pce.13439">through special leaf structures</a>, and even <a href="https://doi.org/10.1111/pce.14041">through their stomata</a>. But some trees, including coast redwoods, live in both wet and dry environments with intense seasonal variation. </p>
<p>For broad-leaved trees like the <a href="https://doi.org/10.1104/pp.114.242040">holm oak</a>, which grows in Mediterranean climates with dry summers and rainy winters, this seasonal wetness challenge is relatively easy to overcome. Their stomata are on the sheltered undersides of their leaves, which keeps them clear of water, while the leaves’ top surfaces absorb water. But redwoods are conifers, or cone-bearing trees, with <a href="https://ucanr.edu/sites/forestry/California_forests/http___ucanrorg_sites_forestry_California_forests_Tree_Identification_/Coast_Redwood_Sequoia_sempervirens_198/">thin, flat needlelike</a> leaves, and they need a different way to balance the competing goals of repelling and absorbing water. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/457504/original/file-20220411-11-gw6ixl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Oval-shaped opening on a wavy green surface." src="https://images.theconversation.com/files/457504/original/file-20220411-11-gw6ixl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/457504/original/file-20220411-11-gw6ixl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=615&fit=crop&dpr=1 600w, https://images.theconversation.com/files/457504/original/file-20220411-11-gw6ixl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=615&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/457504/original/file-20220411-11-gw6ixl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=615&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/457504/original/file-20220411-11-gw6ixl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=772&fit=crop&dpr=1 754w, https://images.theconversation.com/files/457504/original/file-20220411-11-gw6ixl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=772&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/457504/original/file-20220411-11-gw6ixl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=772&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A single stoma on a tomato leaf, shown via electron microscope.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Stoma#/media/File:Tomato_leaf_stomate_1-color.jpg">Photohound/Wikipedia</a></span>
</figcaption>
</figure>
<p>We knew we wanted to explore how redwoods met the paradoxical challenge of leaf wetness, how much water redwoods could absorb and which leaf features caused differences in water uptake capacity. What we learned came as a total surprise.</p>
<h2>Big trees with big secrets</h2>
<p>Scientists have long known about redwoods’ <a href="https://doi.org/10.1111/j.1365-3040.2004.01207.x">ability to absorb water through their leaves</a>. But figuring out how much water redwoods can absorb this way, and how the capacity to do so might vary from one type of climate to another, is a real challenge in this species. </p>
<p>First, a big redwood has over 100 million leaves with a <a href="https://doi.org/10.1016/j.foreco.2016.05.018">massive amount of surface area</a> for water absorption. And these leaves <a href="https://doi.org/10.1016/j.foreco.2016.05.018">drastically change structure with height</a>, going from long and flat to short and awllike. So we couldn’t get this right by simply picking leaves at ground level.</p>
<p>To complicate matters further, gravity is always pushing down on the giant column of water rising upward through a redwood’s trunk. As a result, leaves at the top of the tree <a href="https://doi.org/10.1038/nature02417">always have less available water</a> than those lower down. The treetop’s inherent dryness should pull water into the leaf more quickly than into water-rich leaves at the bottom, just as a dry sponge picks up water faster than a damp one. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/457508/original/file-20220411-26-5iu2ea.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing historic and current distribution of coast redwoods." src="https://images.theconversation.com/files/457508/original/file-20220411-26-5iu2ea.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/457508/original/file-20220411-26-5iu2ea.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=716&fit=crop&dpr=1 600w, https://images.theconversation.com/files/457508/original/file-20220411-26-5iu2ea.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=716&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/457508/original/file-20220411-26-5iu2ea.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=716&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/457508/original/file-20220411-26-5iu2ea.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=899&fit=crop&dpr=1 754w, https://images.theconversation.com/files/457508/original/file-20220411-26-5iu2ea.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=899&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/457508/original/file-20220411-26-5iu2ea.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=899&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Coast redwoods’ range extends from southern Oregon to California’s Big Sur coast.</span>
<span class="attribution"><a class="source" href="https://www.parks.ca.gov/?page_id=24723">California Department of Parks and Recreation</a></span>
</figcaption>
</figure>
<p>For an accurate picture of how redwoods absorbed water, we needed leaves from trees in wet and dry environments, and from multiple heights on those trees. To get them to their natural gravity-based water levels for analysis, we put our leaf samples in a <a href="https://doi.org/10.1111/pce.13327">fog chamber</a> – in this case, an ice chest hooked up to a room humidifier – and measured weight gain over time to see how much water they could absorb.</p>
<h2>A trail of clues</h2>
<p>As we took apart clusters of redwood shoots to immerse them in fog, we divided each cluster into pieces. Redwood shoot clusters fan out from a woody core and are segmented into individual shoots of multiple ages, each with its own set of leaves. We separated shoots along <a href="https://doi.org/10.1093/treephys/tpu011">the woody central axis</a> from the much more common pliable shoots on the outer edges of each cluster. </p>
<p>It quickly became obvious that shoots from the center axis had leaves that could absorb water three times faster than peripheral leaves. When we looked inside the leaves with a microscope, we understood that they were two completely different types. They don’t look the same on the outside either, but this was so unexpected that we needed to see their internal structure to really convince ourselves. </p>
<p>The axial leaves were packed with water storage cells, but their phloem – tubes in the leaves that export photosynthetic sugars to the tree – appeared to be blocked and useless. If a tree has leaves, the conventional wisdom is that they are there for photosynthesis, but we wondered whether the axial leaves had a different purpose.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/457500/original/file-20220411-13-ve7ex9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two types of redwood shoots" src="https://images.theconversation.com/files/457500/original/file-20220411-13-ve7ex9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/457500/original/file-20220411-13-ve7ex9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/457500/original/file-20220411-13-ve7ex9.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/457500/original/file-20220411-13-ve7ex9.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/457500/original/file-20220411-13-ve7ex9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/457500/original/file-20220411-13-ve7ex9.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/457500/original/file-20220411-13-ve7ex9.jpeg?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"></a>
<figcaption>
<span class="caption">Redwoods’ broad peripheral leaves, shown at left, make up about 95% of the trees’ leaf area and do all the photosynthesis. Their axial leaves, at right, are adept at absorbing water.</span>
<span class="attribution"><span class="source">Alana Chin</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>With some additional measurements, we found that redwoods’ axial leaves are specialized for absorbing water. Differences between the surfaces of axial and peripheral leaves, especially their wax coverage, cause the differences in their water absorption rates.</p>
<p>Unlike the axial leaves, redwoods’ peripheral leaves have waxy surfaces with lots of stomata. This helped to explain how they <a href="https://academic.oup.com/treephys/article/30/10/1260/1658568">photosynthesize year-round</a> regardless of the long wet season in much of their current habitat.</p>
<p>Further analysis showed that the redwoods’ axial leaves account for only about 5% of the trees’ total leaf area, and barely produce enough energy through photosynthesis to maintain themselves. But they contribute up to 30% of the trees’ total water absorption capacity. Together these two types of leaves balance the dueling requirements of photosynthesis and water absorption, allowing redwoods to thrive in both wet and dry habitats. </p>
<p>[<em>More than 150,000 readers get one of The Conversation’s informative newsletters.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-150K">Join the list today</a>.]</p>
<p>Using large-scale <a href="https://www.youtube.com/watch?v=B4JAyIAhgIU&t=89s">tree measurements</a> and <a href="https://doi.org/10.1890/14-1016.1">equations for estimating redwood leaf area</a>, we estimated that these thirsty giants can absorb as much as 105 pounds (48 kilograms) of water in the first hour of a rainfall wetting their leaves. That’s equivalent to 101 pints of beer.</p>
<h2>The significance to redwoods</h2>
<p>Understanding what causes the variation in redwood leaves’ uptake capacity can help us gauge differences in water uptake capabilities among trees and environments, now and in the future. In my opinion, this is the most potentially useful part of our study.</p>
<p>Redwoods vary their two leaf types to suit their local climates. In wet rainforests in the northern part of their range, above Mendocino County, the trees invest in fewer of the axial leaves that are specialized for absorbing water. These leaves are concentrated in the trees’ lower crowns, leaving the photosynthetically <a href="https://doi.org/10.1093/treephys/tpp037">high-performing treetops</a> free to maximize sugar production in the bright sun. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/457510/original/file-20220411-6515-ece0z9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Leaf under a microscope, covered with white dots." src="https://images.theconversation.com/files/457510/original/file-20220411-6515-ece0z9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/457510/original/file-20220411-6515-ece0z9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=510&fit=crop&dpr=1 600w, https://images.theconversation.com/files/457510/original/file-20220411-6515-ece0z9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=510&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/457510/original/file-20220411-6515-ece0z9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=510&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/457510/original/file-20220411-6515-ece0z9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=641&fit=crop&dpr=1 754w, https://images.theconversation.com/files/457510/original/file-20220411-6515-ece0z9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=641&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/457510/original/file-20220411-6515-ece0z9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=641&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wax on the surface of a redwood leaf. The white dots are water-resistant plugs in the stomata.</span>
<span class="attribution"><span class="source">Marty Reed</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>In dry forests on the southern margins of redwoods’ range, trees have more axial leaves in their water-stressed tops. This allows them to take better advantage of briefer leaf-wetting events, but it means they photosynthesize less per leaf area than redwoods in wetter areas. </p>
<p>Redwoods’ ability to shift leaf types to match regional climatic differences may help them adjust to climate change in an <a href="https://theconversation.com/californias-water-supplies-are-in-trouble-as-climate-change-worsens-natural-dry-spells-especially-in-the-sierra-nevada-173142">ever-drier California</a>. That would be good news for conserving these epic trees, and it may be a promising feature to investigate as scientists try to <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1111/tpj.15592">link drought tolerance traits</a> to regional differences among redwood populations.</p><img src="https://counter.theconversation.com/content/179812/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alana Chin received funding from the NSF GRFP</span></em></p>New research shows that coast redwood trees have a surprising adaptation that helps them thrive in both wet and dry environments.Alana Chin, Postdoctoral Fellow in Plant Ecology, Swiss Federal Institute of Technology ZurichLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1764452022-02-06T19:06:56Z2022-02-06T19:06:56ZJust 16% of the world’s coastlines are in good shape – and many are so bad they can never fully recover<figure><img src="https://images.theconversation.com/files/444463/original/file-20220204-25-1luokrn.png?ixlib=rb-1.1.0&rect=5%2C0%2C1911%2C1074&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Leonardo Felippi</span></span></figcaption></figure><p>Only about 16% of the world’s coastal regions are in relatively good condition, according to our <a href="https://doi.org/10.1111/cobi.13874">world-first research released today</a>, and many are so degraded they can’t be restored to their original state.</p>
<p>Places where the land meets the sea are crucial for our planet to function. They support biodiversity and the livelihoods of billions of people. But to date, understanding of the overall state of Earth’s coastal regions has been poor. </p>
<p>Our research, involving an international team of experts, revealed an alarming story. Humanity is putting heavy pressure on almost half the world’s coastal regions, including a large proportion of protected areas. </p>
<p>All nations must ramp up efforts to preserve and restore their coastal regions – and the time to start is right now.</p>
<figure class="align-center ">
<img alt="Fishermen bring their catch ashore a polluted bank" src="https://images.theconversation.com/files/444493/original/file-20220204-21-1qsjehr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/444493/original/file-20220204-21-1qsjehr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/444493/original/file-20220204-21-1qsjehr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/444493/original/file-20220204-21-1qsjehr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/444493/original/file-20220204-21-1qsjehr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/444493/original/file-20220204-21-1qsjehr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/444493/original/file-20220204-21-1qsjehr.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">Coastlines support the livelihoods of billions of people.</span>
<span class="attribution"><span class="source">ROLEX DELA PENA/EPA</span></span>
</figcaption>
</figure>
<h2>Our coasts are vital – and vulnerable</h2>
<p>Coastal regions encompass some of the most diverse and unique ecosystems on Earth. They include coral reefs, kelp forests, seagrass, tidal flats, mangroves, estuaries, salt marshes, wetlands and coastal wooded habitat. </p>
<p>Many animal species, including those that migrate, rely on coastlines for breeding, foraging and protection. Coastal sites are also where rivers discharge, mangrove forests exchange nutrients with the ocean, and tidal flows are maintained.</p>
<p>Humans also need coastlines. Among other functions, they support our fisheries, protect us from storms and, importantly, store carbon to help mitigate climate change.</p>
<p>As much as 74% of the world’s population <a href="https://www.jstor.org/stable/4299200">live within</a> 50 kilometres of the coast, and humans put pressure on coastal environments in myriad ways.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/wetlands-have-saved-australia-27-billion-in-storm-damage-over-the-past-five-decades-153638">Wetlands have saved Australia $27 billion in storm damage over the past five decades</a>
</strong>
</em>
</p>
<hr>
<p>In marine environments, these pressures include:</p>
<ul>
<li>fishing at various intensities</li>
<li>land-based nutrient, organic chemical and light pollution</li>
<li>direct human impacts such as via recreation</li>
<li>ocean shipping</li>
<li>climate change (and associated ocean acidification, sea-level rise and increased sea surface temperatures).</li>
</ul>
<p>On land, human pressures on our coastlines include:</p>
<ul>
<li>built environments, such as coastal developments </li>
<li>disturbance </li>
<li>electricity and transport infrastructure</li>
<li>cropping and pasture lands, which clears ecosystems and causes chemical and nutrient runoff into waterways.</li>
</ul>
<p>To date, assessments of the world’s coastal regions have largely focused solely on either the land or ocean, rather than considering both realms together. Our research sought to address this.</p>
<figure class="align-center ">
<img alt="cargo ship and dock workers at port" src="https://images.theconversation.com/files/444494/original/file-20220204-17-1eqkxp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/444494/original/file-20220204-17-1eqkxp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=395&fit=crop&dpr=1 600w, https://images.theconversation.com/files/444494/original/file-20220204-17-1eqkxp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=395&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/444494/original/file-20220204-17-1eqkxp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=395&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/444494/original/file-20220204-17-1eqkxp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=496&fit=crop&dpr=1 754w, https://images.theconversation.com/files/444494/original/file-20220204-17-1eqkxp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=496&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/444494/original/file-20220204-17-1eqkxp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=496&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Shipping is among the human activities putting pressure on coastlines.</span>
<span class="attribution"><span class="source">Chad Hipolito/ AP</span></span>
</figcaption>
</figure>
<h2>A troubling picture</h2>
<p>We integrated existing human impact maps for both <a href="https://doi.org/10.1016/j.oneear.2020.08.009">land</a> and <a href="https://doi.org/10.1038/s41598-019-47201-9">ocean</a> areas. This enabled us to assess the spectrum of human pressure across Earth’s coastal regions to identify those that are highly degraded and those intact. </p>
<p>Both maps use data up to the year 2013 – the most recent year for which cohesive data is available. </p>
<p>No coastal region was free from human influence. However, 15.5% of Earth’s coastal regions remained intact – in other words, humans had exerted only low pressure. Many of the intact coastal regions were in Canada, followed by Russia and Greenland. </p>
<p>Large expanses of intact coast were also found elsewhere including Australia, Indonesia, Papua New Guinea, Chile, Brazil and the United States. </p>
<p>Troublingly, 47.9% of coastal regions have been exposed to very high levels of human pressure. And for 84% of countries, more than half their coastal regions were degraded. </p>
<p>What’s more, human pressures were high in about 43% of protected coastal regions – those regions purportedly managed to conserve nature.</p>
<p>Coastal regions containing sea grasses, savannah and coral reefs had the highest levels of human pressure compared to other coastal ecosystems. Some coastal regions may be so degraded they cannot be restored. Coastal ecosystems are highly complex and once lost, it is likely impossible to restore them to their original state. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/5-major-heatwaves-in-30-years-have-turned-the-great-barrier-reef-into-a-bleached-checkerboard-170719">5 major heatwaves in 30 years have turned the Great Barrier Reef into a bleached checkerboard</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="coral reef and boat" src="https://images.theconversation.com/files/444499/original/file-20220204-23-jqk017.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/444499/original/file-20220204-23-jqk017.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/444499/original/file-20220204-23-jqk017.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/444499/original/file-20220204-23-jqk017.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/444499/original/file-20220204-23-jqk017.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/444499/original/file-20220204-23-jqk017.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/444499/original/file-20220204-23-jqk017.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">
<figcaption>
<span class="caption">Coastal regions containing coral are among the world’s most degraded by human activity.</span>
<span class="attribution"><span class="source">AP</span></span>
</figcaption>
</figure>
<h2>So where to now?</h2>
<p>It’s safe to say intact coastal regions are now rare. We urge governments to urgently conserve the coastal regions that remain in good condition, while restoring those that are degraded but can still be fixed.</p>
<p>To assist with this global task, we have made our dataset publicly available and free to use <a href="https://doi.org/10.48610/fd85061">here</a>.</p>
<p>Of course, the right conservation and restoration actions will vary from place to place. The actions might include, but are not limited to:</p>
<ul>
<li><p>improving environmental governance and laws related to encroaching development</p></li>
<li><p>increasing well-resourced protected areas</p></li>
<li><p>mitigating land-use change to prevent increased pollution run-off</p></li>
<li><p>better community and local engagement</p></li>
<li><p>strengthening Indigenous involvement in managing coastal regions</p></li>
<li><p>effective management of fishing resources</p></li>
<li><p>addressing climate change</p></li>
<li><p>tackling geopolitical and socioeconomic drivers of damage to coastal environments.</p></li>
</ul>
<p>In addition, there’s an urgent need for national and global policies and programs to effectively managing areas where the land and ocean converge. </p>
<p>Humanity’s impact on Earth’s coastal regions is already severe and widespread. Without urgent change, the implications for both coastal biodiversity and society will become even more profound.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-traditional-owners-and-officials-came-together-to-protect-a-stunning-stretch-of-wa-coast-163078">How Traditional Owners and officials came together to protect a stunning stretch of WA coast</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/176445/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brooke Williams receives funding from an Australian Government Research Training Program Scholarship. </span></em></p><p class="fine-print"><em><span>James Watson has received funding from the Australian Research Council and National Environmental Science Program. He serves on scientific committees for Bush Heritage Australia and BirdLife Australia.</span></em></p><p class="fine-print"><em><span>Amelia Wenger 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>All nations must ramp up efforts to preserve and restore their coastal regions – and the time to start is right now.Brooke Williams, Postdoctoral research fellow, The University of QueenslandAmelia Wenger, Research fellow, The University of QueenslandJames Watson, Professor, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1692152021-10-05T12:26:37Z2021-10-05T12:26:37ZCalifornia’s latest offshore oil spill could fuel pressure to end oil production statewide<figure><img src="https://images.theconversation.com/files/424530/original/file-20211004-21-1s1dd34.jpg?ixlib=rb-1.1.0&rect=13%2C8%2C2982%2C1989&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Oiled sand in Huntington Beach, Calif., after a 126,000-gallon spill from an offshore oil pipeline.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/oil-is-washed-up-on-huntington-state-beach-after-a-126-000-news-photo/1235691140">Nick Ut/Getty Images</a></span></figcaption></figure><p><em>An oil spill first reported on Oct. 2, 2021, has released thousands of gallons of crude oil into southern California coastal waters. The source is believed to be a leak in an underwater pipeline connected to an oil drilling platform 17.5 miles offshore. Oil has washed ashore in Huntington Beach and Newport Beach and into coastal marshes. Orange County has requested a federal disaster declaration. Charles Lester, director of the Ocean and Coastal Policy Center at the University of California Santa Barbara’s Marine Science Institute, explains the scope of this spill.</em></p>
<h2>How large is this spill, and how much coastline is affected?</h2>
<p>Reports estimate that about 126,000 gallons of oil have spilled from a ruptured undersea pipeline, potentially affecting 25 miles of coast in Orange County. As a precaution, the state of California has <a href="https://wildlife.ca.gov/News/southern-california-fisheries-closure-implemented-due-to-oil-spill">closed coastal fisheries</a> from Huntington Beach to the city of Dana Point, extending out 6 miles from shore. </p>
<p>This stretch of shoreline includes many extremely important marine and coastal resources, from the <a href="https://bolsachica.org/the-wetlands/ecology/">Bolsa Chica wetlands</a> complex to the <a href="https://www.parks.ca.gov/?page_id=27926">Dana Point State Marine Conservation Area</a>. </p>
<p>Wetlands provide critical wildlife habitat and are nurseries for many marine species. The ones in California are part of a network of wetlands along the Pacific coast that <a href="https://pacificbirds.org/birds-migration/the-habitats/">supports many sensitive local and migratory bird species</a>. Rocky shorelines and tide pool areas along the Newport and Laguna coasts are also critically important habitat areas for <a href="https://www.seaandsageaudubon.org/BirdInfo/birdinfoparksoc.htm">birds</a>, <a href="https://explorebeaches.msi.ucsb.edu/sandy-beach-life/marine-mammals">marine mammals</a> and <a href="https://www.kcet.org/shows/socal-wanderer/where-to-spot-socals-coastal-wildlife">other wildlife</a>.</p>
<p>Since Spanish settlement began in the mid-1500s, California has lost <a href="https://mywaterquality.ca.gov/eco_health/wetlands/extent/loss.html">90% or more of its coastal wetlands</a>. That makes the ones that are left, such as the <a href="http://www.santa-ana-river-trail.com/trail/Talbert_Marsh.asp">Talbert Marsh</a> near the mouth of the Santa Ana River, even more important.</p>
<p>Orange County also has dozens of popular beaches that millions of residents and visitors use. They generate <a href="https://www.travelcostamesa.com/visittheoc/wp-content/uploads/2018/12/Orange-County-Tourism-Economic-Impact_2017_10052018_FINAL.pdf">billions of dollars in revenue</a> for the state’s coastal economy every year. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/424595/original/file-20211004-23-hqlic8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Large group of seals lying at the water's edge." src="https://images.theconversation.com/files/424595/original/file-20211004-23-hqlic8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/424595/original/file-20211004-23-hqlic8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424595/original/file-20211004-23-hqlic8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424595/original/file-20211004-23-hqlic8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424595/original/file-20211004-23-hqlic8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424595/original/file-20211004-23-hqlic8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424595/original/file-20211004-23-hqlic8.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>
<figcaption>
<span class="caption">Seals on the beach in Carpinteria, Calif., near Santa Barbara.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/hsP2m5">Shai Bl/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>How does this event compare to other major spills in California?</h2>
<p>Offshore oil development always entails some risk of an oil spill. California’s ocean waters have experienced multiple spills over the past 50-plus years. </p>
<p>The largest was the <a href="https://www.smithsonianmag.com/history/how-oil-spill-50-years-ago-inspired-first-earth-day-180972007/">1969 Santa Barbara offshore oil blowout</a>, which sent more than 3 million gallons of oil onto local beaches. It was a major disaster that helped launch the modern environmental movement. </p>
<p>Other large spills since then include the <a href="https://wildlife.ca.gov/OSPR/NRDA/American-Trader">American Trader tanker spill</a> off the coast of Orange County in 1990, which released 416,000 gallons, and the <a href="https://wildlife.ca.gov/OSPR/NRDA/Refugio">2015 Refugio pipeline spill</a> in Santa Barbara County, which released 123,000 gallons from an underground pipeline on land into the ocean. </p>
<p>Offshore oil production presents spill risks from both platform drilling activities and the facilities that move oil from offshore to refineries and storage facilities on land – including undersea and underground pipelines. The vast array of oil and gas infrastructure along California’s coast requires constant monitoring and maintenance to avoid spills like this one.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/424537/original/file-20211004-27-oofjzn.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of California offshore energy operations." src="https://images.theconversation.com/files/424537/original/file-20211004-27-oofjzn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/424537/original/file-20211004-27-oofjzn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424537/original/file-20211004-27-oofjzn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424537/original/file-20211004-27-oofjzn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424537/original/file-20211004-27-oofjzn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424537/original/file-20211004-27-oofjzn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424537/original/file-20211004-27-oofjzn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">There are 23 oil and gas platforms in federal waters off the southern California coast (14 producing, nine non-producing). There also are four platforms and five artificial islands with oil operations in state waters (seven producing, two being decommissioned).</span>
<span class="attribution"><a class="source" href="https://www.slc.ca.gov/wp-content/uploads/2018/10/Offshore-California.pdf">California State Lands Commission</a></span>
</figcaption>
</figure>
<h2>What kind of technology does the state have to contain and clean up the oil?</h2>
<p>Time is of the essence in oil spill response. Responders are deploying physical barriers such as <a href="https://apnews.com/article/environment-and-nature-california-environment-wildlife-wetlands-19019fb634f7d13d10a89f11b4b90424">booms and using skimmer boats</a> to contain and clean up oil floating on the ocean’s surface. They also are <a href="https://www.latimes.com/california/story/2021-10-02/coast-guard-rushes-to-contain-newport-beach-oil-slick">constructing sand berms</a> in front of wetlands to protect sensitive areas from oil washing in with the tides. </p>
<p>Other cleanup technologies include using <a href="https://response.restoration.noaa.gov/oil-and-chemical-spills/oil-spills/resources/dispersants-guided-tour.html">chemical and biological agents</a> to help break down and disperse oil in the water column, and possibly <a href="https://response.restoration.noaa.gov/oil-and-chemical-spills/oil-spills/resources/in-situ-burning.html">burning off oil</a> to help remove it from the water. Aerial reconnaissance will help the Coast Guard and state agencies track the location and scale of the spill. </p>
<h2>What possible impacts of this spill are you most concerned about?</h2>
<p>I am most worried about oil’s <a href="https://response.restoration.noaa.gov/oil-and-chemical-spills/oil-spills/how-oil-harms-animals-and-plants-marine-environments.html">acutely toxic effects on marine and coastal wildlife</a>, including seabirds and other species that inhabit our coastal wetlands. Once oil gets into the marshes and sensitive shoreline locations, it becomes <a href="https://response.restoration.noaa.gov/sites/default/files/Oil_Spills_in_Marshes.pdf">very difficult to clean up</a>. </p>
<p>I am also concerned about longer-term impacts to sensitive wetland and rocky shoreline environments. Oil spills have a significant impact on our coastal economies, from fisheries to recreational activities, including beach closures.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/rIMu_OuaTKQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Many local officials in California worry that the spill in Huntington Beach could have long-term harmful effects on beaches and wildlife.</span></figcaption>
</figure>
<h2>Offshore drilling is very unpopular in California. How long do you expect it will continue?</h2>
<p>I expect that many Californians will see this spill as yet more evidence that the state and the nation should make a swift transition to alternative energy sources, such as solar power and offshore wind. Burning oil and other fossil fuels is one of the <a href="https://www.epa.gov/ghgemissions/global-greenhouse-gas-emissions-data">main sources of carbon dioxide emissions</a> that are heating the planet and changing its climate. </p>
<p>Californians are <a href="https://theconversation.com/trumps-push-for-new-offshore-drilling-is-likely-to-run-aground-in-california-89952">consistently against new offshore oil development</a>: In one recent poll, <a href="https://www.ppic.org/wp-content/uploads/ppic-statewide-survey-californians-and-the-environment-july-2021.pdf">72% opposed it</a>. That reflects concern about oil spills and effects on fisheries and other competing ocean uses, as well as the impacts of climate change.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/424596/original/file-20211004-19-fbyep8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Gloved hands holding a small shorebird streaked with oil." src="https://images.theconversation.com/files/424596/original/file-20211004-19-fbyep8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/424596/original/file-20211004-19-fbyep8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424596/original/file-20211004-19-fbyep8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424596/original/file-20211004-19-fbyep8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424596/original/file-20211004-19-fbyep8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424596/original/file-20211004-19-fbyep8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424596/original/file-20211004-19-fbyep8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A veterinarian examines an oiled sanderling at a wildlife care center in Huntington Beach on Oct. 4, 2021.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/veterinarian-duane-tom-examines-a-sanderling-a-small-shore-news-photo/1235697388">Mindy Schauer/MediaNews Group/Orange County Register via Getty Images)</a></span>
</figcaption>
</figure>
<p>Gov. Gavin Newsom has ordered that by 2035, all new cars and passenger trucks sold in California <a href="https://www.gov.ca.gov/2020/09/23/governor-newsom-announces-california-will-phase-out-gasoline-powered-cars-drastically-reduce-demand-for-fossil-fuel-in-californias-fight-against-climate-change/">must be zero-emission vehicles</a>. He also has asked the <a href="https://ww2.arb.ca.gov/">California Air Resources Board</a> to analyze how to <a href="https://www.gov.ca.gov/2021/04/23/governor-newsom-takes-action-to-phase-out-oil-extraction-in-california/">phase out oil extraction statewide by 2045</a>. </p>
<p>Many Californians would like that to <a href="https://www.greentechmedia.com/articles/read/how-should-california-wind-down-its-fossil-fuel-industry">happen even sooner</a>. I’m sure this latest disaster will only intensify pressure to end oil production in California, on land and offshore.</p>
<p>[<em>Over 110,000 readers rely on The Conversation’s newsletter to understand the world.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=100Ksignup">Sign up today</a>.]</p><img src="https://counter.theconversation.com/content/169215/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charles Lester has worked in coastal management for three decades, including 20 years with the California Coastal Commission, a state agency with planning and regulatory authority over coastal development. He served as the agency's executive director from 2011 to 2016. He receives funding for his current work on coastal adaptation to sea level rise from sources including the California Ocean Protection Council and the University of California. He is a board member of Save Our Shores, an ocean and coastal conservation organization, and a member of the Sierra Club and the Surfrider Foundation.</span></em></p>Offshore oil drilling has a long history in California, but is highly unpopular today. The latest major spill is likely to fuel efforts to wind down oil and gas production statewide.Charles Lester, Director, Ocean and Coastal Policy Center, Marine Science Institute, University of California, Santa BarbaraLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1649062021-08-03T12:34:42Z2021-08-03T12:34:42ZClimate change is already disrupting US forests and coasts – here’s what we’re seeing at 5 long-term research sites<figure><img src="https://images.theconversation.com/files/412976/original/file-20210724-19-5tond4.jpg?ixlib=rb-1.1.0&rect=0%2C353%2C3872%2C2231&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists have been consistently documenting environmental changes at research sites like this one in the Cascade Mountains for decades.</span> <span class="attribution"><a class="source" href="https://andrewsforest.oregonstate.edu/research/highlights/small-headwater-streams-export-carbon">US Forest Service</a></span></figcaption></figure><p>Record-breaking heat waves and drought have left West Coast rivers <a href="https://wildlife.ca.gov/News/cdfw-successfully-relocates-11-million-hatchery-salmon-until-klamath-river-drought-conditions-improve">lethally hot for salmon</a>, literally <a href="https://www.cbc.ca/news/canada/british-columbia/intertidal-animals-ubc-research-1.6090774">cooked millions of mussels and clams</a> in their shells and left <a href="https://www.cnn.com/2021/07/22/world/wildfires-siberia-us-canada-climate-intl/index.html">forests primed to burn</a>. The extraordinary severity of 2021’s heat and drought, and its <a href="https://theconversation.com/the-year-the-west-was-burning-how-the-2020-wildfire-season-got-so-extreme-148804">fires</a> and <a href="https://www.nytimes.com/live/2021/07/16/world/europe-flooding-germany">floods</a>, has many people questioning whether climate change, fueled by human actions, is progressing even faster than studies have predicted and what that means for the future.</p>
<p><a href="https://www.michaelpnelson.com/biography">As</a> <a href="https://scholar.google.com/citations?user=Nd58MnUAAAAJ&hl=en">ecologists</a>, we have watched climate change play out over decades at long-term research sites in forests, fields and coastal areas across the U.S. </p>
<p>A recent <a href="https://esajournals.onlinelibrary.wiley.com/toc/21508925/2021/12/5">series of five papers</a> in the journal Ecosphere presents more than 25 case studies from these sites, providing a unique perspective on the changes underway and what’s likely ahead as the planet continues to warm.</p>
<p>Here are snapshots of what we’re seeing firsthand in the National Science Foundation’s Long-Term Ecological Research Network sites, from the effect of increasing fires in Oregon’s Cascades to shifting marine life off the coast of Maine, and surprising resilience in Baltimore’s urban forests. </p>
<h2>Forests of the Pacific Northwest</h2>
<p>In the Cascade Mountains of the Pacific Northwest, scientists have been tracking changes in the <a href="https://andrewsforest.oregonstate.edu/">H.J. Andrews Experimental Forest</a>, a 16,000-acre watershed, for 70 years. The forest is a blend of iconic old-growth hemlock, cedar and Douglas fir trees, many of them 400 to 500 years old; steep terrain; fast, cold-running streams; and a smattering of forest plantations.</p>
<p>While it’s tempting to see permanence in an old-growth forest, the climate may be exceeding thresholds, pushing even these ecosystems dominated by long-lived trees into conditions outside of anything they have experienced.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/cdHHFS72y9A?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Scientists at work inside the H.J. Andrews Experimental Forest.</span></figcaption>
</figure>
<p>In the coming century, the rising temperature is expected to prolong summer droughts and increase winter floods as <a href="https://link.springer.com/article/10.1007/s00382-021-05805-w">snow melts sooner or falls as rain</a>.</p>
<p>As a result, we anticipate more frequent and more severe forest fires, more <a href="https://theconversation.com/trees-are-dying-of-thirst-in-the-western-drought-heres-whats-going-on-inside-their-veins-162385">trees dying</a> and shifts in stream and land ecosystems. New species, such as timber wolves, are likely to move in, while some native species, such as the <a href="https://doi.org/10.1016/j.biocon.2021.109168">Northern spotted owl</a>, disappear. We’ll also likely see shifts in public values and land management that can either help or hurt species’ survival.</p>
<p>These changes will interact with one another in surprising, perhaps unimaginable, ways. The biological responses to changes in the physical systems have, thus far, been subtle and variable, but that could change. Even with records going back more than 70 years, the magnitude and direction of future changes is largely uncertain – we can anticipate some changes, but there may be tipping points and interactions that we don’t yet understand.</p>
<h2>Eastern forests – rural and urban</h2>
<p>In the Northeastern U.S., the forests are younger because humans have been using the land longer and in more intense ways. At the <a href="https://www.nrs.fs.fed.us/ef/locations/nh/hubbard-brook/">Hubbard Brook Experimental Forest</a> in the White Mountains of New Hampshire, the ecosystem has shown remarkable resilience to disturbance.</p>
<p>It was established by the Forest Service in 1955, and early research included clear-cutting entire watersheds to study the <a href="https://hubbardbrook.org/">impact on the water quality and ecosystems</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/q63KgaWjNGc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Collecting data at Hubbard Brook Experimental Forest.</span></figcaption>
</figure>
<p>Current research there focuses on whether this capacity for resilience has been degraded by climate change, acid rain, invasion by pests and pathogens and the inexorable <a href="https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.3434">march of climate migrant species</a>, such as oak and pine that may displace the sugar maple and beech that currently dominate the forest.</p>
<p>These <a href="https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.3434">recent results</a> suggest that in 50 years, these northern hardwood forests will likely still resemble the communities we see today, with sugar maple and beech dominating a closed-canopy forest. However, the responses of forest growth and tree species to the drivers of change now suggest that their resilience may be overwhelmed toward the end of the 21st century, resulting in a forest with markedly different structure and services. </p>
<p>This might come as a surprise, but in comparing urban forest research sites, like a network <a href="https://lternet.edu/site/baltimore-ecosystem-study/">site in Baltimore</a>, with rural forests, we have found that some urban forests may actually be <a href="https://doi.org/10.1016/j.foreco.2019.117665">more resilient</a>. In the same paper describing the resilience at Hubbard Brook, researchers discuss how forests in the mid-Atlantic and southeastern regions of the U.S. have experienced changes in biodiversity because of fire suppression and high deer populations that don’t affect natural areas in cities as much. These changes reduce the resilience of these forests, resulting in the loss of oak and a suite of biodiversity and ecosystem services associated with these species.</p>
<h2>Midwestern fields</h2>
<p><a href="https://www.kbs.msu.edu/">Kellogg Biological Station</a> in southwest Michigan is the only Long-Term Ecological Research site in an agricultural setting. Insects, and how they might change in a warming future, are a concern.</p>
<p>Research here shows how the arrival of <a href="https://www.kbs.msu.edu/">invasive predators</a> has changed native and exotic predator and prey communities in ways that may make the ecosystems less resilient. Invasive species have the potential to reshape interactions among entire communities, in turn influencing ecosystem function and ecosystem services.</p>
<p><iframe id="fDSfi" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/fDSfi/1/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Like shifting climate patterns, the movement of species outside their native ranges can have profound consequences for biodiversity and the functioning of communities in the invaded areas. In agricultural ecosystems of the north-central U.S., successive invasions of exotic lady beetle predators have influenced community structure and ecosystem processes with wide-ranging effect on both natural and managed ecosystems. Now the question is whether the changing climate will affect insect communities, with implications for pest management and native species loss.</p>
<h2>Shifting marine life in the Atlantic</h2>
<p>Changes in biodiversity are especially dynamic in coastal marine sites.</p>
<p>In 2012, a researcher reported seeing a blue crab, <em>Callinectes sapidus</em>, swimming in the estuary of the <a href="https://pie-lter.ecosystems.mbl.edu/welcome-plum-island-ecosystems-lter">Plum Island Ecosystem Long-Term Ecological Research</a> site, an estuary in northeastern Massachusetts we call PIE. The site is in the cooler waters of the Gulf of Maine and 70 miles (114 km) north of the historical northern limit of blue crabs. </p>
<p>Then, in 2014, a male fiddler crab, <em>Minuca pugnax</em>, turned up. Like the blue crab, its historic northern limit was south of PIE. Field surveys found that fiddler crabs were now not only in PIE, but as far north as Maine.</p>
<p><iframe id="mtjcA" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/mtjcA/5/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>The northern shift of these crabs’ habitat as the water warms reflects what scientists are <a href="https://www.climate.gov/news-features/featured-images/search-cooler-waters-marine-species-are-shifting-northward-or-diving">seeing for marine species globally</a> as global temperatures rise.</p>
<p>The movement of species into nonnative ranges, whether as an introduced species or via climate-driven range shifts, represents a <a href="https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.3432">biological disturbance in the system</a>. What that will mean for these species in the future, and the structure, function and services of ecosystems they move into, is less clear. Coastal marine ecosystems are especially dynamic, and our colleagues at sites in Massachusetts, Virginia, Georgia, Florida and California are helping us understand and predict these effects.</p>
<h2>Tracking change today to respond to the future</h2>
<p>These snapshots reflect changes elsewhere across the Long-Term Ecological Research Network. </p>
<p>The network has roughly 2,000 researchers at 28 sites around the country as well as in Antarctica and on a Pacific coral reef. Together they represent thousands of years of on-the-ground observation and experimentation. Their research feeds into global climate analysis, like the <a href="https://www.ipcc.ch/assessment-report/ar6/">Intergovernmental Panel on Climate Change report</a> expected to be released on Aug. 9, 2021.</p>
<p>Predicting the future of ecosystems is difficult, particularly under an accelerating force like climate change. These extensive long-term datasets, with everything from changes in soil nutrients to the growth and decline of animal species, provide insight into the changes underway to guide responses for the future.</p>
<p><em>The following scholars contributed to this article: <a href="https://scholar.google.com/citations?user=WL0EyIUAAAAJ&hl=en">Christie A. Bahlai</a>, <a href="https://scholar.google.com/citations?user=5d0benYAAAAJ&hl=en">John J. Battles</a>, <a href="https://www.researchgate.net/profile/Natalie-Cleavitt">Natalie L. Cleavitt</a>, <a href="https://scholar.google.com/citations?user=wPQ8Qz0AAAAJ&hl=en">Timothy J. Fahey</a>, <a href="https://scholar.google.com/citations?user=IYnA8YoAAAAJ&hl=en">David Samuel Johnson</a>, <a href="https://scholar.google.com/citations?user=c_IMsNoAAAAJ&hl=en">Douglas A. Landis</a>,
<a href="https://scholar.google.com/citations?user=7pGKCTsAAAAJ&hl=en">Joe Sullivan</a>, <a href="https://www.linkedin.com/in/laura-templeton-9436a1186/">Laura Templeton</a> and <a href="https://scholar.google.com/citations?user=fbMG_5YAAAAJ&hl=en">Natalie S. Van Doorn</a>.</em></p><img src="https://counter.theconversation.com/content/164906/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Paul Nelson receives funding from the National Science Foundation (grant DEB-2025755). </span></em></p><p class="fine-print"><em><span>Peter Mark Groffman receives funding from the National Science Foundation, the United States Department of Agriculture, and NASA.</span></em></p>This kind of research, with consistent data collection at the same locations over time, helps support global understanding of climate change.Michael Paul Nelson, Professor of Environmental Ethics and Philosophy, Oregon State UniversityPeter Mark Groffman, Professor, CUNY Graduate CenterLicensed 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/1526412021-02-01T12:11:36Z2021-02-01T12:11:36ZWhy ocean pollution is a clear danger to human health<figure><img src="https://images.theconversation.com/files/377023/original/file-20210104-23-1gss1v1.jpg?ixlib=rb-1.1.0&rect=4%2C2%2C994%2C661&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Plastic waste is the most visible component of ocean pollution.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/bali-indonesia-february-12-2017-beach-1036531933">Maxim Blinkov/Shutterstock</a></span></figcaption></figure><p>Ocean pollution is widespread, worsening, and poses a clear and present danger to human health and wellbeing. But the extent of this danger has not been widely comprehended – until now. <a href="https://annalsofglobalhealth.org/article/10.5334/aogh.2831/">Our recent study</a> provides the first comprehensive assessment of the impacts of ocean pollution on human health. </p>
<p>Ocean pollution is a complex mixture of toxic metals, plastics, manufactured chemicals, petroleum, urban and industrial wastes, pesticides, fertilisers, pharmaceutical chemicals, agricultural runoff, and sewage. More than 80% arises from land-based sources and it reaches the oceans through rivers, runoff, deposition from the atmosphere – where airborne pollutants are washed into the ocean by rain and snow – and direct dumping, such as pollution from waste water treatment plants and discarded waste. Ocean pollution is heaviest near the coasts and most highly concentrated along the coastlines of low-income and middle-income countries. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/376987/original/file-20210104-23-86a6lu.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Infographic showing how sources of ocean pollution" src="https://images.theconversation.com/files/376987/original/file-20210104-23-86a6lu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/376987/original/file-20210104-23-86a6lu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=849&fit=crop&dpr=1 600w, https://images.theconversation.com/files/376987/original/file-20210104-23-86a6lu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=849&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/376987/original/file-20210104-23-86a6lu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=849&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/376987/original/file-20210104-23-86a6lu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1067&fit=crop&dpr=1 754w, https://images.theconversation.com/files/376987/original/file-20210104-23-86a6lu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1067&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/376987/original/file-20210104-23-86a6lu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1067&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 ‘pollution-berg’.</span>
<span class="attribution"><span class="source">Will Stahl-Timmins/Boston College/Centre Scientifique de Monaco</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Ocean pollution can also be found far beyond national jurisdictions in the open oceans, the deepest oceanic trenches, and on the shores of remote islands. Ocean pollution knows no borders. </p>
<h2>The most hazardous ocean pollution</h2>
<p><strong>Plastic waste</strong> is the most visible component of ocean pollution. More than <a href="https://www.journals.uchicago.edu/doi/10.1093/reep/rez012">ten million tonnes</a> of plastic enter the seas every year. The majority of this breaks down into microplastic particles and accumulates in coastal and deep-sea sediments. </p>
<p>Some large pieces float in the water for decades ending up as massive concentrations where currents converge and circulate. The Pacific Ocean’s <a href="https://theconversation.com/it-might-be-the-worlds-biggest-ocean-but-the-mighty-pacific-is-in-peril-150745">so called “garbage patch”</a> is a well-known example. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/it-might-be-the-worlds-biggest-ocean-but-the-mighty-pacific-is-in-peril-150745">It might be the world's biggest ocean, but the mighty Pacific is in peril</a>
</strong>
</em>
</p>
<hr>
<p><a href="https://theconversation.com/microplastics-have-even-been-blown-into-a-remote-corner-of-the-pyrenees-115503">Microplastics</a> contain multiple toxic chemicals that are added to plastics to make them flexible, colourful, waterproof or flame-resistant. These include carcinogens, neurotoxins, and endocrine disruptors – chemicals that interfere with hormones, and can cause cancer, birth defects, and reduced fertility. </p>
<p>These chemical-laden particles enter the food chain and accumulate in fish and shellfish. When humans eat seafood contaminated with these materials, we ingest millions of microplastic particles and the many chemicals they carry. Though there is still <a href="https://theconversation.com/plastics-in-oceans-are-mounting-but-evidence-on-harm-is-surprisingly-weak-93877">debate</a> on the harm to humans from microplastics, exposure to these chemicals increases the risk of all the diseases that they cause. Virtually all of us <a href="https://www.sciencedirect.com/science/article/pii/S0160412020322297">have microplastics in our bodies</a> today.</p>
<p><strong>Mercury</strong> is widespread in the oceans, and the major culprit is coal burning in <a href="https://www.unenvironment.org/resources/publication/global-mercury-assessment-2018">homes and industry</a>. All coal contains mercury, and when it burns, mercury vaporises, enters the atmosphere, and eventually washes into the sea. <a href="https://theconversation.com/gold-rush-mercury-legacy-small-scale-mining-for-gold-has-produced-long-lasting-toxic-pollution-from-1860s-california-to-modern-peru-133324">Gold mining is another source</a>, as mercury is used to dissolve gold from the ore.</p>
<p>Mercury can accumulate to high levels in predatory fish such as tuna and swordfish, which are in turn eaten by us. <a href="https://wedocs.unep.org/bitstream/handle/20.500.11822/29830/GMAKF_EN.pdf?sequence=1&isAllowed=y">Contaminated fish</a> can be especially dangerous if eaten by expectant mothers. Exposure of mercury to infants in the womb <a href="https://www.sciencedirect.com/science/article/abs/pii/S0010945215001768?via%3Dihub">can damage</a> developing brains, reducing IQ and increasing risks for autism, ADHD, and other learning disorders. Adult mercury exposure increases risks <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5295325/">for heart disease</a> and <a href="https://ehjournal.biomedcentral.com/articles/10.1186/1476-069X-2-8">dementia</a>.</p>
<p><strong>Petroleum pollutants</strong> from oil spills threaten the marine microorganisms that produce much of the Earth’s oxygen by reducing their capacity for photosynthesis. These beneficial microorganisms use solar energy to convert atmospheric CO₂ into oxygen and <a href="https://www.nature.com/articles/s41598-017-08425-9">are also affected</a> by <a href="https://www.epa.gov/international-cooperation/persistent-organic-pollutants-global-issue-global-response#pops">organic pollutants</a> and <a href="https://theconversation.com/plastic-poisons-ocean-bacteria-that-produce-10-of-the-worlds-oxygen-and-prop-up-the-marine-food-chain-117493">other chemicals</a>. When there is a major oil spill, the impact can be huge.</p>
<p><strong>Coastal pollution</strong> from industrial waste, agricultural runoff, pesticides, and sewage increases the frequency of harmful algal blooms, known as red tides, brown tides, and green tides. These blooms produce powerful toxins like ciguatera and domoic acid that accumulate in fish and shellfish. When ingested, these toxins can cause dementia, amnesia, paralysis, and even rapid death. When inhaled, they can cause asthma.</p>
<p><strong>Dangerous microorganisms</strong> result from a combination of coastal pollution and warming seas, which encourages their spread. Harmful bacteria such as the vibrio species – found in warmer waters and responsible for <a href="https://www.cdc.gov/vibrio/index.html">vibriosis</a>, a potentially fatal illness – are now appearing further north and causing life-threatening infections. There’s a high risk that cholera, caused by <em>vibrio cholerae</em>, <a href="https://www.researchgate.net/figure/Reports-of-Vibrio-cholerae-from-sea-water-samples_fig4_277890080">could spread</a> to new, previously unaffected areas.</p>
<p>And the health impacts of ocean pollution fall disproportionately on indigenous peoples, coastal communities and vulnerable populations <a href="https://annalsofglobalhealth.org/article/10.5334/aogh.2831/">in the Global South</a>, underlining the planetary scale of this environmental injustice.</p>
<h2>Political will and scientific evidence</h2>
<p>While the findings in this report are alarming, the good news is that ocean pollution, as with all forms of pollution, can be controlled and prevented. Bans on single-use plastics and better waste sorting can curb pollution at its source, especially plastic waste, both on land and at sea.</p>
<p>Wise governments have curbed other forms of pollution by deploying control strategies based on law, policy, technology, and targeted enforcement. The US, for example, <a href="https://www.corning.com/emea/en/products/environmental-technologies/the-us-has-come-a-long-way-since-the-u-s-clean-air-act.html">has reduced air pollution by 70%</a> since the passage of the Clean Air Act in 1970. They have saved thousands of lives. They have <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)32345-0/fulltext">proven highly cost-effective</a>.</p>
<p>Countries around the world are now applying these same tools to control ocean pollution. <a href="https://www.frontiersin.org/articles/10.3389/fmars.2018.00478/full">Boston Harbour in Massachusetts</a> and Victoria Harbour in Hong Kong have been cleaned. Estuaries from Chesapeake Bay in the US to the Seto Inland Sea in Japan have been rejuvenated. Some coral reefs have been restored, such as <a href="https://ocean.si.edu/ecosystems/coral-reefs/reefs-american-samoa-story-hope">those in American Samoa</a>, where vigilance, protection and quick response have happened in relation to various pollution threats.</p>
<p>These successes have boosted economies, increased tourism, restored fisheries, and improved health. They demonstrate that broad control of ocean pollution is feasible and their benefits will last for centuries. Our study <a href="https://annalsofglobalhealth.org/article/10.5334/aogh.2831/">offers some clear recommendations</a> for preventing and controlling ocean pollution, including transitioning to cleaner energy, developing affordable alternatives to fossil fuel-based plastics, reducing human, agricultural and industrial discharges, and expanding <a href="https://theconversation.com/uk/topics/marine-protected-areas-10558">Marine Protected Areas</a>.</p>
<p>Protecting the planet is a global concern and our collective responsibility. Leaders who recognise the gravity of ocean pollution, acknowledge its growing dangers, engage civil society, and take bold, evidence-based action to stop pollution at source will be essential for preventing ocean pollution and safeguarding our own health.</p><img src="https://counter.theconversation.com/content/152641/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jacqueline McGlade receives funding from UKRI Global Challenges Research Fund (EPSRC)</span></em></p><p class="fine-print"><em><span>Philip Landrigan receives funding from Center Scientifique de Monaco and the Prince Albert II de Monaco Fondation</span></em></p>Polluted oceans don’t just harm wildlife, they are a source of ill health for humans too.Jacqueline McGlade, Professor of Natural Prosperity, Sustainable Development and Knowledge Systems, UCLPhilip Landrigan, Professor and Director, Global Public Health Program and Global Pollution Observatory, Schiller Institute for Integrated Science and Society, Boston CollegeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1477982020-10-20T12:19:26Z2020-10-20T12:19:26ZRestoring seagrasses can bring coastal bays back to life<figure><img src="https://images.theconversation.com/files/364103/original/file-20201018-13-1fbnw6t.jpg?ixlib=rb-1.1.0&rect=17%2C35%2C3944%2C2934&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Eelgrasses covered with small snails, which keep the leaves clean by feeding on algae that live on them.</span> <span class="attribution"><span class="source">Jonathan Lefcheck</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>A century ago Virginia’s coastal lagoons were a natural paradise. Fishing boats bobbed on the waves as geese flocked overhead. Beneath the surface, miles of seagrass gently swayed in the surf, making the seabed look like a vast underwater prairie. </p>
<p>More than <a href="https://ocean.si.edu/ocean-life/plants-algae/seagrass-and-seagrass-beds">70 species</a> of seagrasses grow in shallow waters around the world, on every continent except Antarctica. In Virginia, beds of <a href="https://www.fisheries.noaa.gov/feature-story/importance-eelgrass">eelgrass</a> (<em>Zostera marina</em>) provided habitat for bay scallops and food for birds, and kept barrier islands from washing away. Eelgrass was so common that people who lived near the shore packed and baled it to <a href="https://www.jlconline.com/how-to/insulation/a-history-of-eel-grass-insulation_o">use as insulation</a> for homes, schools and hospitals. </p>
<p>In the 1930s, however, pandemic plant disease and repeated hurricanes eliminated the eelgrass along Virginia’s eastern shore. The once-vibrant seafloor became barren mud, leading to a loss of “wildfowl, the cream of salt-water fishing, most of the clams and crabs, and all of the bay scallops,” sportsman and publisher <a href="https://cpl.org/the-derrydale-press/">Eugene V. Connett</a> <a href="https://www.jamescumminsbookseller.com/pages/books/239493/eugene-v-connett/duck-shooting-along-the-atlantic-tidewater-chapters-by-frederick-c-lincoln-lynn-bogue-hunt">wrote in 1947</a>. </p>
<p>We are marine scientists who study <a href="https://scholar.google.com/citations?user=bVEVdsEAAAAJ&hl=en">seagrasses</a>, <a href="https://scholar.google.com/citations?user=wTArpJgAAAAJ&hl=en">marine biodiversity</a> and <a href="https://scholar.google.es/citations?user=l6zTkPUAAAAJ&hl=en">coastal ecosystems</a>. In a newly published study, we describe the results of a 20-year mission to reintroduce eelgrass into Virginia coastal bays using a <a href="http://dx.doi.org/%2010.1126/sciadv.abc6434">novel seed-based approach</a>. </p>
<p>This project has now restored 9,600 acres of seagrasses across four bays – one of the most successful marine restoration efforts anywhere in the world. It has triggered large increases in fishes and invertebrates, made the water clearer and trapped large quantities of carbon in seafloor sediments, helping to slow climate change. We see this work as a blueprint for restoring and maintaining healthy ecosystems along coastlines around the world.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graphic of seagrasses and other near-shore ecosystems." src="https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=359&fit=crop&dpr=1 600w, https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=359&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=359&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=451&fit=crop&dpr=1 754w, https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=451&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=451&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Seagrasses and other coastal habitats stabilize coastlines, store carbon and provide habitat for fish and shellfish.</span>
<span class="attribution"><a class="source" href="https://live.staticflickr.com/65535/49983475236_35e2e8d974_o.png">Hisham Ashkar/GRID-Arendal</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Why didn’t seagrasses recover naturally?</h2>
<p>Development, nutrient runoff and other human impacts have damaged marshes, mangroves, coral reefs and seagrasses in many bays and estuaries worldwide. Loss or shrinkage of these key habitats has reduced commercial fisheries, increased erosion, made coastlines more vulnerable to floods and storms and harmed many types of aquatic life. Rapid climate change has compounded these effects through <a href="https://theconversation.com/ocean-warming-has-fisheries-on-the-move-helping-some-but-hurting-more-116248">rising global temperatures</a>, more <a href="https://theconversation.com/more-frequent-and-intense-tropical-storms-mean-less-recovery-time-for-the-worlds-coastlines-123335">frequent and severe storms</a> and <a href="https://theconversation.com/as-climate-change-alters-the-oceans-what-will-happen-to-dungeness-crabs-61501">ocean acidification</a>.</p>
<p>In the late 1990s, local residents told two of us who are longtime students of seagrasses (Robert “JJ” Orth and Karen McGlathery) that they had spotted small patches of eelgrass in shallow waters off Virginia’s eastern shore. For years the conventional view had been that seagrasses in this area had not recovered from the events of the 1930s because human activities had <a href="https://doi.org/10.1016/j.aquabot.2005.07.007">made the area inhospitable for them</a>.</p>
<p>But studies showed that water quality in these coastal bays was <a href="https://doi.org/10.1007/BF02782971">comparatively good</a>. This led us to explore a different explanation: Seeds from healthy seagrass populations elsewhere along the Atlantic coast simply weren’t reaching these isolated bays. Seagrasses are underwater flowering plants, so seeds are among the main ways they reproduce and spread to new environments.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Satellite map showing project area in coastal Virginia." src="https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=536&fit=crop&dpr=1 600w, https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=536&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=536&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=674&fit=crop&dpr=1 754w, https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=674&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=674&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Eelgrass beds were restored in four bays at the southern tip of Virginia’s eastern shore on the Atlantic coast.</span>
<span class="attribution"><span class="source">David J. Wilcox/VIMS</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Sowing a new crop</h2>
<p>From our <a href="https://doi.org/10.2307/1941597">earlier research</a>, we knew that when eelgrass seeds fall from the parent plant, they sink to the sea bottom quickly and don’t move far from where they land. We also knew that these seeds don’t germinate until late fall or early winter. This meant that if we collected the seeds in spring, when eelgrass flowers, we could hold them until the fall, helping them survive over the months in between.</p>
<p>We decided to try reseeding eelgrass in the areas where they were missing. Starting in 1999, we collected seeds by hand from underwater meadows in nearby Chesapeake Bay – plucking the long reproductive shoots, bringing them back to our laboratory and holding them in large outdoor seawater tanks until they released their seeds naturally. After about 10 years we started gathering the grasses using a custom-built underwater “lawn mower” to collect many more of the reproductive shoots than we could by hand. </p>
<p>In 2001 we sowed our first round by simply tossing seeds from a boat. Our first test plots covered 28 acres of mud flats in waters 2 to 3 feet deep. Returning the following year, we saw new seedlings sprouting up. </p>
<p>Each year since then, the <a href="https://www.vims.edu">Virginia Institute of Marine Science</a> and the <a href="https://www.nature.org/en-us/about-us/where-we-work/united-states/virginia/">Nature Conservancy’s Virginia Coast Reserve</a>, along with staff and students from the <a href="https://www.vcrlter.virginia.edu">University of Virginia</a>, have led a team of scientists and citizens to collect and seed a combined 536 acres of bare bottom in several coastal bays.</p>
<p>These initial plots took off and rapidly expanded. By 2020 they covered 9,600 acres across four bays. Several factors helped them flourish. These bays are naturally flushed with cool, clean water from the Atlantic Ocean. And they lie off the tip of Virginia’s eastern shore, where there is little coastal development. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/K9NyfPLINtk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">To restore eelgrasses to Virginia coastal bays, scientists collected grasses in other areas, harvested their seeds and spread them by hand.</span></figcaption>
</figure>
<h2>Sheltering marine life and storing carbon</h2>
<p>Since eelgrass disappeared from these bays in the 1930s, human understanding of seagrass ecosystems has evolved. Today people don’t pack their walls full of seagrass insulation but instead value different services they provide, such as habitat for fish and shellfish – including many <a href="https://doi.org/10.1111/conl.12645">commercially and recreationally important species</a>.</p>
<p>Scientists and government agencies also have recognized the importance of coastal systems in capturing and storing so-called “<a href="https://oceanservice.noaa.gov/facts/bluecarbon.html">blue carbon</a>.” In fact, we now know that seagrasses constitute a globally significant <a href="https://doi.org/10.1038/ngeo1477">carbon sink</a>. They are a key tool for reducing carbon dioxide in the atmosphere and <a href="https://doi.org/10.1038/s41598-020-64094-1">slowing climate change</a></p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p>
<p>We are working to understand the valuable services that our restored seagrass beds provide. To our surprise, fish and invertebrates returned within only a few years as the meadows expanded. These organisms have established extensive food webs that include species ranging from tiny seahorses to 6-foot-long sandbar sharks.</p>
<p>Other benefits were equally dramatic. Water in the bays become clearer as the seagrass canopy trapped floating particles and deposited them onto the bottom, burying significant stocks of carbon and nitrogen in sediments bound by the grasses’ roots. Our research is the first to verify the overall net carbon captured by seagrass, and is now being used to issue carbon offset credits that in turn <a href="https://vaseagrant.org/eelgrass-carbon-credits/">create more funds for restoration</a>. </p>
<p>One big question was whether restoring seagrasses could make it possible to bring back bay scallops, which once generated millions of dollars for the local economy. Since bay scallops no longer existed in Virginia, we obtained broodstock from North Carolina, which we have <a href="https://chesapeakebaymagazine.com/return-of-the-bay-scallop/">reared and released annually</a> since 2013. Regular surveys now reveal a growing population of bay scallops in the restored eelgrass, although there is still some way to go before they reach levels seen in the 1930s.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial photo of restored seagrass beds" src="https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Restored seagrass beds (dark areas) along Virginia’s Atlantic coast, with sunlight reflecting from a small island.</span>
<span class="attribution"><span class="source">Jonathan Lefcheck</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A model for coastal restoration</h2>
<p>Repairing damaged ecosystems is such an urgent mission worldwide that the United Nations has designated 2021-2030 as the <a href="https://www.decadeonrestoration.org/">U.N. Decade on Ecosystem Restoration</a>. We see the success we have achieved with eelgrass restoration as a prime model for similar efforts in coastal areas around the world. </p>
<p>Our project focused not only on reviving this essential habitat, but also on charting how restoring seagrasses affected the ecosystem and on the co-restoration of bay scallops. It provides a road map for involving scholars, nonprofits organizations, citizens and government agencies in an ecological mission where they can see the results of their work.</p>
<p>Recent assessments show that the restored zone only covers about 30% of the total habitable bottom in our project area. With continued support, eelgrass – and the many benefits it provides – may continue to thrive and expand well into the 21st century.</p><img src="https://counter.theconversation.com/content/147798/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert J. Orth receives funding from the Virginia Department of Environmental Quality, National Oceanographic and Atmospheric Administration Office of Coastal Zone Management, U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, Virginia Recreational Fishing License Fund, Maryland Department of Natural Resources, Maryland Department of the Environment, Keith Campbell Foundation for the Environment, Virginia Sea Grant . He is an elected official on the Gloucester County Board of Supervisors as an independent. </span></em></p><p class="fine-print"><em><span>Jonathan Lefcheck is supported by the Michael E. Tennenbaum Secretarial Scholar gift to the Smithsonian Institution.</span></em></p><p class="fine-print"><em><span>Karen McGlathery receives funding from the National Science Foundation, the National Fisheries and Wildlife Foundation, and Virginia Sea Grant.</span></em></p>Healthy seagrasses form underwater meadows teeming with fish and shellfish. A successful large-scale restoration project in Virginia could become a model for reseeding damaged seagrass beds worldwide.Robert J. Orth, Professor of Marine Science, Virginia Institute of Marine ScienceJonathan Lefcheck, Research Scientist, Smithsonian Environmental Research Center, Smithsonian InstitutionKaren McGlathery, Professor of Environmental Sciences and Director, Environmental Resilience Institute, University of VirginiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1399392020-07-31T10:03:08Z2020-07-31T10:03:08ZSea level rise: three visions of a future summer holiday at the coast<figure><img src="https://images.theconversation.com/files/350436/original/file-20200730-21-letoor.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3888%2C2590&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/sand-castle-on-beach-347251772">Sukhanova Daria/Shutterstock</a></span></figcaption></figure><p>The COVID-19 pandemic will ensure summer 2020 is a washout for most. With international travel restrictions limiting holidays abroad, many people in the UK have opted to stay somewhere closer to home. As a result, there have been <a href="https://www.bbc.co.uk/news/uk-53190209">remarkable increases</a> in the number of visitors to beaches across the UK. Thousands flocked to <a href="https://www.bbc.co.uk/news/uk-england-dorset-53176717">a beach in Bournemouth</a> on a single day in June, causing the local council to declare a major incident. </p>
<p>But far greater disruptions to our summer holidays lie ahead. About half of all tourism <a href="https://sustainabledevelopment.un.org/content/documents/178208-%202013April_New%20York_LC.pdf">takes place in coastal areas</a>, but with global warming set to <a href="https://www.pnas.org/content/116/23/11195.short">raise sea levels by somewhere around two metres</a> over the next 80 years, how will our relationship with the coast change? </p>
<p>Will we commemorate the old coastal boundaries with forlorn sojourns above the sunken land? Will we recreate the beach in the heart of our cities? Or will we preserve the drowned coast as a nature reserve – a quiet memorial to what was lost?</p>
<p>We imagined <a href="https://www.tandfonline.com/doi/full/10.1080/21568316.2019.1667861">three different versions</a> of what a beach holiday might look like as climate change eclipses the coastline we once knew.</p>
<h2>1. Floating in place</h2>
<p>Sea level rise may seem a distant threat, but resorts and other tourism operators are already considering how they can stay near the coast and operate above the water. On the Caribbean island of <a href="https://www.telegraph.co.uk/travel/destinations/caribbean/antigua-and-barbuda/codrington/hotels/barbuda-belle-hotel/">Barbuda</a>, resort huts have been built on stilts.</p>
<p>The aim is to keep tourism viable in the same place it has thrived for decades, while minimising damage from higher water levels.</p>
<p><a href="https://www.seasteading.org/">Seasteading</a> is one answer to this conundrum. The idea to build settlements on platforms at sea originated with the hope of creating more sustainable and equal societies away from land. The technology is still being developed, while researchers consider the <a href="https://www.seasteading.org/overview/">engineering, legal and business</a> implications. </p>
<p><a href="https://www.nature.com/articles/s41598-020-67736-6">New research</a> suggests that coastal flooding could threaten up to 20% of global GDP by 2100, with much of it tied to the tourism industry. Tourism could instead become a new source of income for seasteads. Given the dwindling coastal space for tourists, creating new spaces out at sea might be a way to meet the problem of sea level rise head on. </p>
<figure class="align-center ">
<img alt="A cabin raised several feet above the sea water on stilts." src="https://images.theconversation.com/files/350433/original/file-20200730-25-mb7vfw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350433/original/file-20200730-25-mb7vfw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350433/original/file-20200730-25-mb7vfw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350433/original/file-20200730-25-mb7vfw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350433/original/file-20200730-25-mb7vfw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350433/original/file-20200730-25-mb7vfw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350433/original/file-20200730-25-mb7vfw.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">Heavy engineering could keep some resorts afloat.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cabin-still-stands-where-there-used-243645865">Serge Skiba/Shutterstock</a></span>
</figcaption>
</figure>
<h2>2. Bringing the beach to you</h2>
<p>The <a href="http://www.redspottedhanky.com/destination-guides/adventure/best-uk-urban-beaches/">urban beach</a> is a concept that’s growing in popularity worldwide. It involves creating sandy areas in towns and cities by importing sand onto concrete. There may also be artificial pools and fairground rides. <a href="https://www.culturewhisper.com/r/things_to_do/best_urban_beaches_in_london_summer/7366">Each one has different features</a>. There are family-friendly options, and those catered to adults, with cocktail bars or restaurants. </p>
<p>The opportunities for hedonism are still there, but instead of travelling miles to enjoy it, it’s right on your doorstep. Less travel means less carbon emissions, and urban beaches might help ease pressure on the real coast.</p>
<p>Perhaps the most famous urban beach is the <a href="https://en.parisinfo.com/discovering-paris/major-events/paris-plages">Paris Plage</a>. Since its opening in 2002, Parisians and summer tourists have been able to lounge under palm trees on the banks of the river Seine. It cost over two million Euros to create and has since been extended due to its popularity. </p>
<figure class="align-center ">
<img alt="The Paris Plage – a sandy beach with potted palms overlooking the River Seine." src="https://images.theconversation.com/files/350439/original/file-20200730-19-1efdcy6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350439/original/file-20200730-19-1efdcy6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350439/original/file-20200730-19-1efdcy6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350439/original/file-20200730-19-1efdcy6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350439/original/file-20200730-19-1efdcy6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350439/original/file-20200730-19-1efdcy6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350439/original/file-20200730-19-1efdcy6.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">‘Sous les pavés, la plage!’</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/paris-france-august-13-2014-public-245349922">Efired/Shutterstock</a></span>
</figcaption>
</figure>
<p>The <a href="https://nottinghambeach.co.uk/">Nottingham Riviera</a> is an attempt to recreate this success in the UK. The landlocked beach in the middle of the city has sand and water, amusement arcades and beach bars.</p>
<p>The urban beach is becoming an industry in itself, with <a href="http://www.beach-events.co.uk/we-do-beach_builds/">companies</a> specialising in fake beaches that can be built as seasonal fixtures or permanent areas. If reaching the coast becomes too arduous in the future, these examples could provide everything needed for a seaside experience without the sea.</p>
<h2>3. Rewilding the coast</h2>
<p>Perhaps the most pragmatic solution is to accept nature taking its course and relinquish control as rising seas reshape the terrain. Allowing the new coastline to rewild could create millions of acres of new wetlands – habitats that are very good at <a href="https://www.nature.com/articles/s41598-019-40763-8">storing carbon</a> and that have deteriorated by <a href="https://www.mdpi.com/1660-4601/16/10/1818">about 50% since 1900</a>. </p>
<p><a href="https://rewildingeurope.com/news/the-european-rewilding-network-welcomes-the-uks-largest-coastal-wetland-creation-project/">Examples</a> from Hong Kong, Spain, and Wallasea Island in the UK demonstrate how turning heavily managed coastal areas into new habitats can create new opportunities for wildlife and people. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/rising-seas-to-keep-humans-safe-let-nature-shape-the-coast-107837">Rising seas: to keep humans safe, let nature shape the coast</a>
</strong>
</em>
</p>
<hr>
<p>So does the Mexican island, <a href="http://www.tourism4development2017.org/solutions/mayakoba-tourism-development/">Mayakoba</a>. Its unique mangrove forests were damaged and polluted by the building of numerous hotel chains on the seafront, but today, <a href="https://www.e-unwto.org/doi/pdf/10.18111/9789284419746">only 10% of these hotels remain</a> on the coast.</p>
<p>The local community abandoned their high-density model of tourism and protected the dunes and mangroves, which were being eroded by excessive development. New canal networks were dug to create an estuary, attracting birds and amphibians. This new wetland was designated as a nature reserve and visitors arrived to enjoy a new kind of tourist experience.</p>
<figure class="align-center ">
<img alt="A floating jetty surrounding by mangrove swamp." src="https://images.theconversation.com/files/350458/original/file-20200730-27-z5oqsv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350458/original/file-20200730-27-z5oqsv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350458/original/file-20200730-27-z5oqsv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350458/original/file-20200730-27-z5oqsv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350458/original/file-20200730-27-z5oqsv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350458/original/file-20200730-27-z5oqsv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350458/original/file-20200730-27-z5oqsv.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">
<figcaption>
<span class="caption">Rewilding the coast would provide new wetland habitat for threatened species.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/laradanielle/15239772257/in/photolist-pdFPm6-577Ag9-EBNh1H-HU3SYL-5ji1NG-5ji9p7-5ji8kE-7yTc1t-5je6kp-5jiw3s-7yX157-7yTczx-5je9Ep-5jitLu-5je2Sz-5jhKoG-5jimjQ-7yTceB-5jdtkz-7yTdyr-5jiyDu-5ji991-5jhXuu-7yTbt2-5ji6w1-7yWXYo-5jiCE5-7yWXTA-7yTcke-7yTdFM-7yTbmX-5jdCX4-7yTcCZ-5jdwWX-7yTd1c-7yWYzS-5jeici-5jiGSQ-5jdFQc-5jdDA2-5jiuwy-7yTdL8-7yTbCp-5jetwT-7yWYgs-5jizfW-7yWYSL-7yTbUT-7yTcSr-5jivuj">Lara Danielle/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Visitor capacity and beach activities were reduced to ensure sensitive coastal environments could remain protected. But allowing the sea back into reclaimed coastal territory allowed a more sustainable model of tourism to flourish – one which could be replicated elsewhere as sea levels rise.</p>
<p>But before that can happen, our views of the coast must change. Humans once saw land and sea as <a href="https://press.uchicago.edu/ucp/books/book/chicago/H/bo14312647.html">a continuation of one another</a>, rather than two discrete entities. Reviving this concept could allow us to navigate a future in which once certain borders have blurred beyond recognition.</p><img src="https://counter.theconversation.com/content/139939/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sea levels could be two metres higher by 2100. How will our relationship to the drowned coast change?Nick Davies, Research Fellow in Sustainable Cities and Transport, University of SalfordDavid Jarratt, Senior Lecturer in Tourism Management, University of Central LancashireLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1352292020-04-06T14:18:06Z2020-04-06T14:18:06ZA South African theatre project explores collective solutions to saving the ocean<figure><img src="https://images.theconversation.com/files/325701/original/file-20200406-104477-a42tb5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Courtesy Lalela uLwandle</span></span></figcaption></figure><p>The earth’s oceans are under grave threat. Scientists in many fields have pointed to the large-scale negative shifts brought about by <a href="https://www.sciencedirect.com/science/article/pii/S0025326X17301650">human-made pollutants</a>, <a href="https://onlinelibrary.wiley.com/doi/pdf/10.1111/issj.12159?casa_token=yo1hu6jL9h4AAAAA%3AnsdpJweEdPal13QVMb1RBN-jnfJR10c-yU12iCoDEtfaYHHF0kXGv65aIEIPV2KMuRnwjr7Qdzk1tedw">mining</a> and <a href="http://www.scielo.org.za/pdf/sajs/v112n9-10/04.pdf">overfishing</a>.</p>
<p>How people now choose to behave, make collective decisions and build solidarity around the health of oceans has an impact not just on our own species but on all life on earth.</p>
<p><a href="https://www.empatheatre.com/lalela-ulwandle">Lalela uLwandle</a> (Listen to the Sea) is a theatre production in South Africa that was developed by the <a href="https://www.empatheatre.com/about">Empatheatre</a> group after listening to the voices of coastal dwellers that care for or live off the ocean. The Lalela uLwandle research and engagement project was implemented along the KwaZulu-Natal coastline in 2019. </p>
<p>The production was first staged at home but has now embarked on an international tour. On 7 June it was <a href="https://www.jozigist.co.za/empatheatre-at-united-nations-world-oceans-week-in-new-york-why-storytelling-is-the-sacred-medicine-ocean-governance-needs/?utm_source=rss&utm_medium=rss&utm_campaign=empatheatre-at-united-nations-world-oceans-week-in-new-york-why-storytelling-is-the-sacred-medicine-ocean-governance-needs">performed</a> at the United Nations in New York for World Oceans Week. Lead actress and co-director of Empatheatre, Mpume Mthombeni also gave a speech at the UN headquarters on 8 June, World Oceans Day.</p>
<h2>A chorus of voices</h2>
<p>The idea for the play emerged from a <a href="https://risingsunchatsworth.co.za/123628/community-oil-gas-mining-kzn-coast/">public consultation meeting</a>. It was between community representatives from small towns along the coastline, and the <a href="https://www.sapia.org.za">Petroleum Association of South Africa</a>. Many felt they had not been adequately consulted in an environmental impact assessment for permits to drill for oil and gas along the coastline. </p>
<p>The association, a regulatory body meant to consider public needs when granting or denying such licences, was sympathetic to some of the arguments. But the consultation process failed to make room for the different perspectives and concerns in the room.</p>
<p>In response, a team of researchers working in ocean governance from Rhodes University and the Durban University of Technology began the Lalela project. It set out to explore how different coastal people, in and around the coastal city of Durban, make sense of their relationship with the ocean. </p>
<p>The research participants included a broad spectrum. They were small-scale and subsistence fishers, marine scientists, activists, church followers, marine educators at the aquarium and <a href="https://www.britannica.com/science/sangoma">sangomas</a> (traditional healers). </p>
<p>The opening question was simple: What are your first memories of the sea? It’s important because the symbolic, scientific and spiritual meanings of the oceans are key to understanding <a href="https://link.springer.com/article/10.1007/s40152-020-00163-5">humans’ relationship with the oceans</a>. Memories, belief systems, stories and myths are powerful ways in which we make sense of our world and choose to act on and in it.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/325696/original/file-20200406-103690-1c7nil7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/325696/original/file-20200406-103690-1c7nil7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325696/original/file-20200406-103690-1c7nil7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325696/original/file-20200406-103690-1c7nil7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325696/original/file-20200406-103690-1c7nil7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325696/original/file-20200406-103690-1c7nil7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325696/original/file-20200406-103690-1c7nil7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325696/original/file-20200406-103690-1c7nil7.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">Faye (Allison Cassels) recounts the wonder of baby cuttlefish.</span>
<span class="attribution"><span class="source">Casey Pratt</span></span>
</figcaption>
</figure>
<p>The research team partnered with <a href="http://www.uncannyjustness.org/empatheatre.html">Empatheatre</a>, a collective who use research-based theatre as a participatory decision-making tool for social justice. They have tackled issues related to street-level drug use (<em><a href="https://www.youtube.com/watch?v=jguiaUniBbE">Ulwembu</a></em>), gender and migration (<em><a href="https://www.youtube.com/watch?v=Dg4P38dbBao">The Last Country</a></em>), and mining (<em><a href="https://soilandash.weebly.com/">Soil&Ash</a></em>). They wove these incredible everyday stories of the sea, together with archival material, into the production <em>Lalela uLwandle</em>. </p>
<h2>On stage among the audience</h2>
<p><em>Lalela uLwandle</em> draws on the stories of three people. Nolwandle is a marine educator whose mother is a Zionist and grandmother a sangoma. Niren is a young environmental activist whose family has a long history of seine-net fishing. Faye is a retired marine biologist reflecting on life as a scientist and activist. </p>
<p>Audience members sit in a circle with the actors and witness these intergenerational stories. They recount how the ocean is linked to, among other things, livelihoods, medicine and healing, and scientific study. Included is the site of the sea for spiritual connections with ancestors.</p>
<p>The play deals with acts of past and present power and exclusion in South Africa. It performs the painful experiences of <a href="https://www.sahistory.org.za/article/forced-removals-south-africa">forced removals</a> under <a href="https://www.sahistory.org.za/article/history-apartheid-south-africa">apartheid</a>, which robbed many of a life on the coast. It explores how extractive mining on land and sea, and industrial fishing, continue to create forms of oppression and exclusion. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/325707/original/file-20200406-151304-1hujff8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/325707/original/file-20200406-151304-1hujff8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/325707/original/file-20200406-151304-1hujff8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325707/original/file-20200406-151304-1hujff8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325707/original/file-20200406-151304-1hujff8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325707/original/file-20200406-151304-1hujff8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325707/original/file-20200406-151304-1hujff8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325707/original/file-20200406-151304-1hujff8.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">Nolwandle (Mpume Mthombeni) performs the symbolic destruction of homes.</span>
<span class="attribution"><span class="source">Kelly Daniels</span></span>
</figcaption>
</figure>
<p>It also performs the tensions between environmental justice and environmental conservation. These are frequently played out <a href="https://www.sciencedirect.com/science/article/abs/pii/S0964569117304015">in real life</a> when local people are restricted from accessing sites of heritage and livelihood in <a href="http://mpaforum.org.za/marine-protected-areas/">Marine Protected Areas</a>.</p>
<p>Last year the play toured six small towns on the KwaZulu-Natal coast, with a final week’s <a href="https://www.iol.co.za/mercury/goodlife/listen-to-the-sea-33807711">run</a> in <a href="https://www.britannica.com/place/Durban">Durban</a>. The general public came to watch along with guests invited from government, civil society, small-scale fisher associations, marine science and conservation. </p>
<p>Each performance was followed by a facilitated discussion. In many, audience members grappled with what it means to think collectively in a time of ocean degradation. They asked of themselves and fellow audience members how the hurt and inequalities in our past, and in the present, should shape thinking on ocean governance. </p>
<h2>If we listened carefully</h2>
<p>South Africa remains deeply divided by racial injustices and <a href="https://www.imf.org/en/News/Articles/2020/01/29/na012820six-charts-on-south-africas-persistent-and-multi-faceted-inequality">economic inequalities</a>. Rather than skirt over these divides <em>Lalela uLwandle</em> told different stories of power and vulnerability. What arose from the research, performances and discussions was how cultural connections offer valuable contributions towards conservation and environmental efforts. </p>
<p>The play offered an invitation to an alternative conversation. One in which culture, science and conservation may, if people learn to listen to each other carefully, find strategic alignment.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/325708/original/file-20200406-196131-1utf8hs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/325708/original/file-20200406-196131-1utf8hs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/325708/original/file-20200406-196131-1utf8hs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325708/original/file-20200406-196131-1utf8hs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325708/original/file-20200406-196131-1utf8hs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325708/original/file-20200406-196131-1utf8hs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325708/original/file-20200406-196131-1utf8hs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325708/original/file-20200406-196131-1utf8hs.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">Niren (Rory Booth) sends a prayer into the ocean for his grandfather.</span>
<span class="attribution"><span class="source">Val Adamson</span></span>
</figcaption>
</figure>
<p>The public discussions showed an encouraging move away from various trade-offs that normally play out. Where big business gains at the expense of poor communities, or conservation wins at the expense of marginal groups, or where marginal groups are awarded socio-economic resources at the expense of environmental conservation. </p>
<p>To find solutions the world desperately needs to become better equipped at more equitable collective decision making. To do that we need to find translation devices between scientific, conservation, cultural and spiritual canons. We need them to spark an imagination for working in solidarity across difference, with and for the oceans that sustain us all. </p>
<p><em>Lalela uLwandle is led by Dylan McGarry and Taryn Pereira at the <a href="https://www.ru.ac.za/elrc/">Environmental Learning Research Centre</a>, Rhodes University, with Neil Coppen and Mpume Mthombeni from <a href="http://www.uncannyjustness.org/empatheatre.html">Empatheatre</a>, and Kira Erwin at the <a href="https://www.dut.ac.za/faculty/engineering/urban_futures/">Urban Futures Centre</a>, Durban University of Technology. Lalela uLwandle forms part of the <a href="https://www.strath.ac.uk/research/strathclydecentreenvironmentallawgovernance/oneoceanhub/">One Ocean Hub</a>, a global action research network led by Strathclyde University and funded by the <a href="https://www.ukri.org/research/global-challenges-research-fund/">UKRI Global Challenge Research Fund</a>.</em></p>
<p><em>This article was updated to include developments around international performances of the play.</em></p><img src="https://counter.theconversation.com/content/135229/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kira Erwin has received funding from the National Research Foundation, as well as other external funders for research projects at the Urban Futures Centre. Her work on Lalela uLwandle is done in-kind with no direct funding.</span></em></p>Empatheatre’s latest production is more than a play about three characters who live near the sea. It’s a model for collective consultation on how to save the ocean.Kira Erwin, Senior researcher, Durban University of TechnologyLicensed 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/1282072020-02-11T13:54:22Z2020-02-11T13:54:22ZClimate change impacts in Bangladesh show how geography, wealth and culture affect vulnerability<figure><img src="https://images.theconversation.com/files/314272/original/file-20200207-27529-1qjeane.jpg?ixlib=rb-1.1.0&rect=17%2C11%2C3903%2C2598&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">River erosion in Bangladesh, Sept. 12, 2019. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/aerial-view-of-river-erosion-in-bangladesh-on-september-12-news-photo/1167512500?adppopup=true">Zakir Hossain Chowdhury / Barcroft Media via Getty Images</a></span></figcaption></figure><p>Unpredictable weather and climate patterns recently prompted New York Times columnist Paul Krugman to proclaim in January 2020 that “<a href="https://www.nytimes.com/2020/01/02/opinion/climate-change-australia.html">Apocalypse will become the new normal</a>.” </p>
<p>Extreme storms, tides and other awful surprises the world has experienced in recent years suggest that Krugman could be right. July 2019 registered the <a href="https://www.noaa.gov/news/july-2019-was-hottest-month-on-record-for-planet">hottest average global temperature on record</a>. Wildfires, like the dangerous blazes of January 2020 <a href="https://www.nytimes.com/interactive/2020/01/03/climate/australia-fires-air.html">in Australia</a>, endanger health and safety. In Venice in November 2019, the <a href="https://www.theatlantic.com/photo/2019/11/photos-of-venice-underwater-highest-tide-in-50-years/601930/">highest tides in 50 years</a> washed <a href="https://slate.com/news-and-politics/2019/11/venice-italy-pictures-video-underwater-flood-storm.html">more than three feet</a> of water over the landmark Piazza San Marco.</p>
<p>About 4,500 miles farther east, in my home country of Bangladesh, people have been living with dangerous flooding for decades. I have devoted my career to understanding how patterns of living <a href="https://www.boisestate.edu/research-hcrc/saleh-ahmeds-hcrc-profile-page/#">combine with climate and weather patterns</a>, making Bangladesh the <a href="https://germanwatch.org/files/Global%20Climate%20Risk%20Index%202019_2.pdf">poster child for global climate change impacts</a>.</p>
<p>During <a href="https://www.terrain.org/2018/a-life-of-science/tranformation-coastal-bangladesh/">floods in 1998</a> I waded chest-deep through floodwaters in Darsana, in southwestern Bangladesh, watching out for dangerous snakes, just to buy rice and kerosene for my family. In 2019, months before the tides that inundated Venice, flooding in Bangladesh <a href="https://www.reuters.com/article/us-southasia-floods/more-than-60-killed-hundreds-of-thousands-displaced-by-flooding-in-bangladesh-idUSKCN1UI1YX">killed more than 60 people</a> and displaced hundreds of thousands.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/312155/original/file-20200127-81357-1pa9geo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/312155/original/file-20200127-81357-1pa9geo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/312155/original/file-20200127-81357-1pa9geo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/312155/original/file-20200127-81357-1pa9geo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/312155/original/file-20200127-81357-1pa9geo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/312155/original/file-20200127-81357-1pa9geo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/312155/original/file-20200127-81357-1pa9geo.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">Floodwaters rise in a village in southern Bangladesh in July 2019.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/due-to-flood-villages-in-the-southern-part-of-bangladesh-news-photo/1155805279?adppopup=true">Mohammad Saiful Islam/Getty Images</a></span>
</figcaption>
</figure>
<p>However, everyone is not equally vulnerable to these threats. In coastal Bangladesh, I have documented the disproportionate nature of climate impacts. To support people living in distressed situations caused by natural hazards, I believe it is essential to understand the complex social landscape of local vulnerability.</p>
<h2>Geographically and socially vulnerable</h2>
<p>Most countries face adverse consequences from climate change, but low-income developing countries are particularly at risk – first, because they have limited capacities to cope; and second, because they rely heavily on <a href="https://www.ipcc.ch/report/ar5/wg2/">farming and fishing</a>. Of all countries in this plight, I believe Bangladesh suffers the most.</p>
<p>While the entire country is exposed to climate stresses, Bangladesh’s densely populated coastal region along the Bay of Bengal is a vulnerability front line where people are constantly exposed to sea level rise, flooding, erosion, tropical cyclones, storm surge, <a href="https://theconversation.com/climate-change-is-making-soils-saltier-forcing-many-farmers-to-find-new-livelihoods-106048">saltwater intrusion</a> and <a href="https://www.taylorfrancis.com/books/e/9781315767802/chapters/10.4324/9781315767802-6">varying rainfall patterns</a>. </p>
<p>Studies show that any change in expected weather and climate patterns will <a href="https://doi.org/10.1007/978-4-431-55411-0_10">seriously reduce Bangladesh’s food security</a>. This will hinder the nation’s efforts to reduce poverty and <a href="https://www.crop.org/Viewfile.aspx?id=1525">reach the United Nations Sustainable Development Goals</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/311299/original/file-20200122-117911-9q0vrr.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/311299/original/file-20200122-117911-9q0vrr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/311299/original/file-20200122-117911-9q0vrr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=442&fit=crop&dpr=1 600w, https://images.theconversation.com/files/311299/original/file-20200122-117911-9q0vrr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=442&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/311299/original/file-20200122-117911-9q0vrr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=442&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/311299/original/file-20200122-117911-9q0vrr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=555&fit=crop&dpr=1 754w, https://images.theconversation.com/files/311299/original/file-20200122-117911-9q0vrr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=555&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/311299/original/file-20200122-117911-9q0vrr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=555&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Farmers come together in field schools, where they discuss how to handle the changing climate.</span>
<span class="attribution"><a class="source" href="http://www.weathermatters.net/perspectives#/climate-stresses-in-coastal-bangladesh/">Saleh Ahmed</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Most people in this disaster-prone region also live in <a href="https://doi.org/10.1016/S0305-750X(98)00136-3">challenging socioeconomic conditions</a>. Evidence shows that race, ethnicity, religion, gender, age and other socioeconomic differences can amplify disaster outcomes and <a href="https://doi.org/10.1111/1540-6237.8402002">shape local vulnerability</a>. For example, women, children and elderly populations are more vulnerable than others because they have limited social and economic resources and access to public and private support before and after disasters.</p>
<p>Connections between land, people, societies and cultures should guide policymakers and leaders to help Bangladesh’s distinct ethnic groups adapt. </p>
<h2>The role of wealth, religion and gender</h2>
<p>In 2017 and 2018 I interviewed 250 local farmers and several others in the Kalapara area of coastal Bangladesh. Many of them were directly impacted by sea level rise, tropical cyclones, coastal flooding, rainfall variability and saltwater intrusion. Kalapara is one of the most climate-vulnerable locations in Bangladesh.</p>
<p>Here residents’ vulnerability depends on religion, ethnicity, gender and the size of their farm operations. Large farmers usually have more money, social power and local influence. They also have better access to various public and private resources that can be critical for coping with environmental stresses. The poor and those with limited resources are least equipped to confront those crises.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/310605/original/file-20200117-72760-1islt22.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/310605/original/file-20200117-72760-1islt22.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/310605/original/file-20200117-72760-1islt22.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/310605/original/file-20200117-72760-1islt22.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/310605/original/file-20200117-72760-1islt22.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/310605/original/file-20200117-72760-1islt22.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/310605/original/file-20200117-72760-1islt22.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/310605/original/file-20200117-72760-1islt22.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">Sea level rise in the Kalapara region of coastal Bangladesh illustrates life on the edge of changing climate patterns.</span>
<span class="attribution"><span class="source">Saleh Ahmed</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Religion can play a delicate role. In Kalapara, Muslims are the religious majority and Hindus are the minority. My own findings indicated that in most cases Muslim farmers earn more money from both farming and nonfarm activities than the Hindu farmers. </p>
<p>Muslim farmers also get better access to early warnings and other public and private resources, such as financial support and food aid in times of disaster. Since Muslims are the religious majority in Bangladesh, they have more social capital and stronger networks than other religious groups. In Kalapara, Hindu farmers are often marginalized and receive limited access to resources in times of crisis.</p>
<p>I have found that gender is a factor too. Most women who go into farming are excluded from local power structures. Men’s farms tend to be larger and earn more money than those owned by women. But female farmers usually earn more money off the farm, by selling poultry or handicrafts, than men do. </p>
<p>Men receive more of the critical early weather and climate warnings than women because they have stronger connections with agricultural extension agents. Men also enjoy easier access to local markets and mobile phones. All of these resources offer them information on weather and climate, whereas women often face barriers because of religious and cultural restrictions. </p>
<h2>Rakhines remain somewhat isolated</h2>
<p>In the complex landscape of local vulnerability in Kalapara, the majority of the people are ethnic Bengalis who are largely divided between Muslims and Hindus. Others are members of the <a href="https://en.wikipedia.org/wiki/Rakhine_people">Rakhine ethnic minority</a>. These farmers, who settled in the region in the late 18th century, came from modern-day Myanmar. At that time most of coastal Bangladesh was covered by forests, which Rakhines cleared to establish their settlements.</p>
<p>As time passed, more and more Bengalis started to settle around the Rakhines in the region. Rakhine farmers’ culture and religion differ substantially from those of mainstream Bengali farmers. Many Rakhines still speak their native language, also called Rakhine, although they can speak some Bangla. </p>
<p>The language barrier limits their ability to participate in local government or other social and political activities. They live in remote villages, and tend not to understand official early warnings of major storms or other natural hazards. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1214107221493264384"}"></div></p>
<h2>Local action guides the world</h2>
<p>Bangladesh’s climate is changing quickly. Adapting to this crisis requires understanding how complex and vulnerable the landscape is. </p>
<p>Policymakers sometimes overlook local social dynamics when providing early warnings, food or other social services. Reacting without careful planning or understanding local societies could leave some people vulnerable and risks overlooking groups who are already under stress because of climate change. As Bangladesh seeks ways to adapt to climate change, it could set an example of inclusive planning for other nations to follow.</p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/128207/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This research was funded by the NOAA (grant NA13OAR4310184) with contributions from USAID under the International Research and Applications Project.</span></em></p>Bangladesh is on the front lines of climate change, but factors including money, gender and religion make some Bangladeshis much more vulnerable than others. Can it find inclusive ways to cope?Saleh Ahmed, Assistant Professor, School of Public Service, Boise State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1141712019-05-17T10:45:16Z2019-05-17T10:45:16ZHydropower dams can harm coastal areas far downstream<figure><img src="https://images.theconversation.com/files/269485/original/file-20190416-147511-1ckv88b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The San Pedro Mezquital River is the last free-flowing river in Mexico's western Sierra Madre.</span> <span class="attribution"><span class="source">Octavio Aburto</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Thousands of hydroelectric dams are under construction around the world, <a href="https://doi.org/10.1073/pnas.1809426115">mainly in developing countries</a>. These enormous structures are one of the world’s largest sources of renewable energy, but they also cause environmental problems.</p>
<p>Hydropower dams <a href="https://energyeducation.ca/encyclopedia/Water_quality_degradation_from_hydropower">degrade water quality along rivers</a>. Water that flows downstream from the dams is depleted of oxygen, which harms many aquatic animals. The reservoirs above dams are susceptible to harmful algal blooms, and can leach toxic metals such as mercury from submerged soil. </p>
<p>We wanted to know whether dams also impact river systems farther away, at the coastlines where rivers flow into the sea. So we performed a <a href="http://doi.org/10.1126/sciadv.aau9875">natural experiment comparing four rivers</a> along Mexico’s Pacific coast – two that are dammed and two that remain free-flowing. We found that damming rivers has measurable negative ecologic and economic effects on coastal regions more than 60 miles (100 kilometers) downstream. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/274975/original/file-20190516-69213-tibbnr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/274975/original/file-20190516-69213-tibbnr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/274975/original/file-20190516-69213-tibbnr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/274975/original/file-20190516-69213-tibbnr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/274975/original/file-20190516-69213-tibbnr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/274975/original/file-20190516-69213-tibbnr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/274975/original/file-20190516-69213-tibbnr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/274975/original/file-20190516-69213-tibbnr.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">Shrimp fishing along the coast of Nayarit, Mexico.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Shrimp_fisherman.jpg">Tomas Castelazo/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Feeding or starving coastlines</h2>
<p>We studied four river outflows along the Pacific Coast of Mexico in the states of Sinaloa and Nayarit. Two of these were from the San Pedro and Acaponeta rivers, which are relatively unrestricted, with over 75% of their flow unobstructed. </p>
<p>The other two outflows came from the nearby Santiago and Fuerte rivers, which have over 95% of their flow retained in reservoirs. In addition to restricting water flow, these reservoirs trap sediments – over 1 million tons per year along the two rivers combined. </p>
<p>In unobstructed rivers, sediment flows downstream and is eventually deposited along the coast, helping to stabilize the shoreline and sometimes even to build it up. We found that this was happening along the free-flowing Acaponeta and San Pedro rivers. </p>
<p>However, because the sediment from the dammed Santiago and Fuerte rivers is no longer carried downstream, wave action takes over at the coast. At the mouths of these two rivers, we found that waves were eroding up to 33 hectares of combined land – equivalent to about 62 football fields – each year, with widespread ecologic and economic effects on the surrounding regions. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/274971/original/file-20190516-69178-1l35y9j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/274971/original/file-20190516-69178-1l35y9j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/274971/original/file-20190516-69178-1l35y9j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=580&fit=crop&dpr=1 600w, https://images.theconversation.com/files/274971/original/file-20190516-69178-1l35y9j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=580&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/274971/original/file-20190516-69178-1l35y9j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=580&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/274971/original/file-20190516-69178-1l35y9j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=729&fit=crop&dpr=1 754w, https://images.theconversation.com/files/274971/original/file-20190516-69178-1l35y9j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=729&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/274971/original/file-20190516-69178-1l35y9j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=729&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 dammed Fuerto and Santiago Rivers show greater erosion where they reach the Pacific coast than the free-flowing San Pedro and Acaponeta rivers. Images at right show coastline changes during the two periods: blue indicates land accretion, red indicates erosion.</span>
<span class="attribution"><a class="source" href="http://dx.doi.org/%2010.1126/sciadv.aau9875">Ezcurra et al., 2019.</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<h2>The ecology of healthy coasts</h2>
<p>Our field research clearly showed that coastal instability resulting from sediment loss at the mouths of the dammed rivers was harming ecosystems along the shore. For example, we found that coastal regions downstream of free-flowing rivers had significantly more plant diversity. Many of these plants were found only in coastal areas, and therefore had high conservation value. </p>
<p>Coastal erosion due to lack of sediment input from the rivers also reduces critical nursery habitat, such as mangrove forest, where many commercially important fish species <a href="https://doi.org/10.1073/pnas.0804601105">spend their juvenile stage</a>. We found that fishing activity at the mouth of the free-flowing San Pedro River was much higher than around the mouth of the dammed Fuerte River. This loss of fishing potential comes at a cost of around US$1.3 million every year. </p>
<p>Reduced sediment flow also deprives coastal estuaries of nutrients. Lucrative shrimp and oyster fisheries in the region we studied rely heavily on nutrient inputs from rivers. In the San Pedro River region, these fisheries generate around $5.8 million yearly; near the dammed rivers, they have been all but abandoned. </p>
<p>Coastal mangrove wetlands also <a href="https://theconversation.com/mangroves-protect-coastlines-store-carbon-and-are-expanding-with-climate-change-81445">protect shorelines</a> from hurricanes and tropical storms, and serve as recreational areas and conservation habitat for wildlife. Knowing this, we calculated that the loss of these ecosystem services around the dammed rivers totals $3.9 million annually.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/274972/original/file-20190516-69189-1c74q1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/274972/original/file-20190516-69189-1c74q1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/274972/original/file-20190516-69189-1c74q1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=404&fit=crop&dpr=1 600w, https://images.theconversation.com/files/274972/original/file-20190516-69189-1c74q1k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=404&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/274972/original/file-20190516-69189-1c74q1k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=404&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/274972/original/file-20190516-69189-1c74q1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=507&fit=crop&dpr=1 754w, https://images.theconversation.com/files/274972/original/file-20190516-69189-1c74q1k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=507&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/274972/original/file-20190516-69189-1c74q1k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=507&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Vegetation profile of sandbars of the free-flowing San Pedro River (A) and dammed Santiago River (B), where receding black mangrove forest is being eroded away into the advancing coastline.</span>
<span class="attribution"><a class="source" href="http://dx.doi.org/10.1126/sciadv.aau9875">Ezcurra et al., 2019</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Still another valuable function that mangrove wetlands perform is <a href="https://theconversation.com/mapping-the-worlds-blue-carbon-hot-spots-in-coastal-mangrove-forests-105793">storing “blue carbon”</a> in plant tissue and soils, reducing the effects of climate change. But when coastlines recede and mangroves are destroyed, this carbon is released. We calculated that mangrove loss in our study region represented a loss of around $130,000 in annual carbon trading potential for this region. </p>
<p>Adding up all of the ecological services that coastal ecosystems provide, we estimate that the economic consequences of shoreline loss around the Santiago and Fuerte rivers related to hydroelectric damming totaled well over $10 million yearly. </p>
<h2>Letting more sediment flow</h2>
<p>Because sediments are so essential to areas around river mouths, <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2013EF000184">reducing sediment trapping</a> behind dams could mitigate some harmful impacts on coastal areas. There are several ways to do this – notably, sediment bypassing, or diverting a portion of the sediments flowing from upriver around dams and allowing it to rejoin the river downstream. </p>
<p>This strategy can be included in new construction or incorporated into existing dams. In addition to reducing dams’ environmental impacts, it also increases dams’ service lives by reducing the rate at which their reservoirs fill up with silt.</p>
<p>To date, environmental impact assessments of large inland dams have often failed to properly analyze the impacts that these dams will have downriver on coastlines, estuaries, deltas and lagoons. Our study shows how important it is to fully account for dams’ environmental and economic impacts along coasts and basins. </p>
<figure>
<iframe src="https://player.vimeo.com/video/177482737" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Critics are challenging a proposed dam on the San Pedro River at Las Cruces.</span></figcaption>
</figure>
<p>Mexico may be at a juncture in its approach to hydropower. The Mexican government recently contracted with Hydro-Quebec, the world’s largest hydroelectric power producer, to <a href="https://www.eluniversal.com.mx/english/hydro-quebec-boost-clean-energy-generation-mexico">revamp existing dams across the country</a>. And a recent study by a Mexican nongovernment organization, SuMar-Voces por la Naturaleza, <a href="https://aristeguinoticias.com/2702/mexico/hidroelectrica-las-cruces-no-es-necesaria-hoy-ni-a-futuro-revela-estudio/">reported</a> that a long-disputed proposal to build a new hydroelectric dam at Las Cruces is neither financially feasible nor needed to meet energy demand for the region, prompting national groups to call for the final cancellation of the project. </p>
<p>We believe that Mexico and all nations working to develop efficient, low-impact energy sources should take a holistic approach to future dam-related projects, so they can weigh their potentially harmful consequences. The coastal effects that we documented should be part of those reviews.</p><img src="https://counter.theconversation.com/content/114171/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Octavio Aburto receives funding from the David and Lucile Packard Foundation, UC MEXUS and the Leona M. and Harry B. Helmsley Charitable Trust.</span></em></p><p class="fine-print"><em><span>Paula Ezcurra does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Thousands of hydropower dams are under construction around the world. New research shows that by cutting off sediment flow, these dams can have big ecological effects on far-off bays and deltas.Paula Ezcurra, Digital Communications Specialist, Gulf of California Marine Program, University of California, San DiegoOctavio Aburto, Assistant Professor of Marine Biology, Scripps Institute of Oceanography, University of California, San DiegoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1111622019-04-03T10:48:29Z2019-04-03T10:48:29ZAs climate change erodes US coastlines, an invasive plant could become an ally<figure><img src="https://images.theconversation.com/files/264680/original/file-20190319-60969-16zf4qr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Phragmites, an invasive species, line this marsh at Sachuest Point in Middletown, Rhode island. </span> <span class="attribution"><a class="source" href="https://flic.kr/p/ohzKs7"> Tom Sturm/USFWS</a></span></figcaption></figure><p>Many invasive species are found along U.S. coasts, including fishes, crabs, mollusks and marsh grasses. Since the general opinion is that invasives are harmful, land managers and communities spend a lot of time and resources attempting to remove them. Often this happens before much is known about their actual effects, either good or bad.</p>
<p>The common reed <em>Phragmites australis</em> is a tall perennial grass with long leaves that invades fresh and brackish wetlands. There it crowds out native species, reducing plant diversity. Managers frequently kill it with herbicides and replace it in brackish marshes with native <em>Spartina alterniflora</em>, or cordgrass, during restoration projects. </p>
<p>But despite its bad reputation, <em>Phragmites</em> provides many benefits that are generally unknown and unappreciated. After <a href="http://runewarkbiology.rutgers.edu/weis%20lab/home.html">studying salt marsh ecology</a> and the impacts of stressors, including invasive plants, for many years, I have concluded that removing this invasive species wherever it is found – especially along vulnerable coastlines – is a very expensive and often foolish procedure. </p>
<h2>Providing food and shelter</h2>
<p><em>Phragmites</em> actually is <a href="https://www.fws.gov/gomcp/pdfs/phragmitesqa_factsheet.pdf">native in the United States</a>, but the native form comprises only a minor component of the high marsh – the zone that typically is above water. A new genetic variety <a href="https://doi.org/10.1073/pnas.032477999">arrived many decades ago</a> and invaded brackish marshes. </p>
<p>In Europe and Asia, where <em>Phragmites</em> is also native, it is valued as an important wetland species. In China, where <em>Spartina alterniflora</em> has arrived, marsh scientists and managers are concerned with the effects of that invader <a href="https://doi.org/10.1016/j.ecoleng.2008.05.013">replacing their beloved <em>Phragmites</em></a>. Human attitudes toward invasive species can be a bit subjective. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/266908/original/file-20190401-177167-1akrb49.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/266908/original/file-20190401-177167-1akrb49.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/266908/original/file-20190401-177167-1akrb49.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/266908/original/file-20190401-177167-1akrb49.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/266908/original/file-20190401-177167-1akrb49.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/266908/original/file-20190401-177167-1akrb49.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/266908/original/file-20190401-177167-1akrb49.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/266908/original/file-20190401-177167-1akrb49.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>
<figcaption>
<span class="caption">An Ohio field overgrow with invasive Phragmites.</span>
<span class="attribution"><a class="source" href="https://www.usgs.gov/media/images/field-overgrown-phragmites">USGS</a></span>
</figcaption>
</figure>
<p>In the 1990s, my research group reviewed the limited state of knowledge on how <em>Phragmites</em> invasions were affecting mid-Atlantic coastal areas. We found a few studies indicating that <a href="https://doi.org/10.1016/S0022-0981(97)00138-X">fish</a> and <a href="http://dx.doi.org/doi:10.3354/meps209071">invertebrates</a> in tidal creeks of <em>Phragmites</em> marshes in New England and the <a href="http://dx.doi.org/10.3354/meps261051">Mid-Atlantic</a> were roughly as <a href="https://doi.org/10.1672/0277-5212(2002)022%5B0326:NUOAPA%5D2.0.CO;2">abundant</a> and diverse as those in <em>Spartina</em> marshes. In other words, we did not find a major negative impact from <em>Phragmites</em> invasions.</p>
<p>We also did some behavioral laboratory studies examining relationships of estuarine animals to <em>Phragmites</em> (reeds) and <em>Spartina</em> (cordgrass). These investigations showed that grass shrimp, fiddler crabs and killifish chose both plants equally, and that both plants gave grass shrimp <a href="https://doi.org/10.1023/A:1011418507078">comparable protection against their predator, killifish</a>. </p>
<p>To check these results in the field, we did studies at a tidal creek with <a href="http://www.urbanhabitats.org/v03n01/benthic_full.html">cordgrass on one side and reeds on the other</a>. Here we again found comparable numbers of animals in the mud on both sides of the creek. </p>
<p>Findings can vary in different locations. Some researchers have found that fish assemblages are similar in both marshes, while others have shown them to be less dense in <em>Phragmites</em>. Some studies found that killifish were clearly <a href="https://doi.org/10.2307/1352890">reduced in Phragmites marshes</a>. </p>
<p>Marsh plants also provide food for many animals after they die and decay, producing detritus that enters estuarine food webs. When we ground up decaying leaves from <em>Phragmites</em> and <em>Spartina</em> and fed it to fiddler crabs and grass shrimp, the two plants provided equivalent nutrition. Both plants supported survival and growth of fiddler crabs, but <a href="https://doi.org/10.1023/A:1014311521708">neither one supported shrimp survival beyond three weeks</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/266910/original/file-20190401-177171-1pyxv2p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/266910/original/file-20190401-177171-1pyxv2p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/266910/original/file-20190401-177171-1pyxv2p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=348&fit=crop&dpr=1 600w, https://images.theconversation.com/files/266910/original/file-20190401-177171-1pyxv2p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=348&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/266910/original/file-20190401-177171-1pyxv2p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=348&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/266910/original/file-20190401-177171-1pyxv2p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=437&fit=crop&dpr=1 754w, https://images.theconversation.com/files/266910/original/file-20190401-177171-1pyxv2p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=437&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/266910/original/file-20190401-177171-1pyxv2p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=437&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Phragmites</em> can spread through aerial seed dispersal or via rhizomes (underground stems).</span>
<span class="attribution"><a class="source" href="http://www.greatlakesphragmites.net/phragbasics/spread/">Great Lakes Phragmites Collaborative</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Habitat for terrestrial animals and plants</h2>
<p>Marshes are habitat for many kinds of birds, both year-round and during migration. <em>Phragmites</em> supports many birds and other land animals, though not as many as <em>Spartina</em>. </p>
<p>Studies comparing the density of individuals or the numbers of species in reeds versus other plants show <a href="https://doi.org/10.1007/BF03161749">variable results</a>. Extensive, dense beds of tall reeds seem to support fewer species of breeding birds than do smaller beds, sparse stands and stands of reeds mixed with other plants. </p>
<p>In some cases, <em>Phragmites</em> appears to benefit roosting birds, songbirds eating seeds during migration or winter, animals taking refuge from flooding in high reed stands and small mammals like cottontails that <a href="https://doi.org/10.1093/aobpla/plt008">hide in reed patches</a>. It appears to harm other species: For example, it shades turtle nesting sites and <a href="https://doi.org/10.1007/s12237-017-0325-z">displaces other plant species</a> in the high salt marsh.</p>
<h2>Absorbing pollutants and buffering shorelines</h2>
<p>Over the past several decades many studies have shown that marshes help clean the environment by filtering water and removing pollutants. <em>Spartina</em> and <em>Phragmites</em> absorb comparable amounts of metal pollutants from sediments into their roots, but <em>Spartina</em> sends more of those toxic materials into its stems and leaves, from which the metals are excreted back into the ecosystem. <em>Phragmites</em> keeps more pollutants in its roots, <a href="https://doi.org/10.1016/S0272-7714(02)00121-X">sequestering them from the rest of the ecosystem</a>. </p>
<p><em>Phragmites</em> also is better at sequestering other pollutants of concern, including <a href="https://doi.org/10.1890/02-5005">nitrogen</a> and <a href="https://doi.org/10.1016/j.ecoleng.2017.08.031">carbon dioxide</a>. By absorbing excess nitrogen from water, <em>Phragmites</em> helps reduce algal blooms and the formation of low-oxygen “dead zones.” And by taking up more carbon dioxide, it reduces carbon dioxide levels in the atmosphere, slowing climate change. </p>
<p>Tidal marshes in New England and the mid-Atlantic are <a href="http://dx.doi.org/10.1007/s12237-016-0166-1">very vulnerable to sea level rise</a>. Many are not increasing their elevation fast enough to keep up, and risk being submerged unless they can elevate faster or move inland. And when steep slopes, houses or roads are located landward of a marsh, it can’t migrate inland.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/266912/original/file-20190401-177163-to2bx3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/266912/original/file-20190401-177163-to2bx3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/266912/original/file-20190401-177163-to2bx3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=420&fit=crop&dpr=1 600w, https://images.theconversation.com/files/266912/original/file-20190401-177163-to2bx3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=420&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/266912/original/file-20190401-177163-to2bx3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=420&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/266912/original/file-20190401-177163-to2bx3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=528&fit=crop&dpr=1 754w, https://images.theconversation.com/files/266912/original/file-20190401-177163-to2bx3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=528&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/266912/original/file-20190401-177163-to2bx3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=528&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Coastal wetlands are threatened by sea level rise, but accumulation of plant matter can help offset this process.</span>
<span class="attribution"><a class="source" href="https://woodshole.er.usgs.gov/project-pages/sea-level-rise_hazards/images/coastalwetlands2.png">Cahoon et al via USGS</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><em>Phragmites</em> creates more detritus when it dies and traps more sediments, thus enabling marshes to elevate <a href="https://doi.org/10.1023/A:1008444502859">more rapidly than <em>Spartina</em></a>. It builds and stabilizes marsh soils, which store carbon; it also protects tidal marshes from erosion associated with sea level rise. At a time when marshes are seriously threatened by climate change, this function is particularly important.</p>
<p>Some people dislike reeds because they grow tall and dense and block homeowners’ views of the water. However, during storms, taller and denser plants provide better protection than shorter, sparser ones. </p>
<h2>A useful invader</h2>
<p>Twenty years ago, marsh biologists J.E. Rooth and J.C. Stevenson observed that <em>Phragmites</em> “may provide resource managers with a strategy of combating sea-level rise, and current control measures <a href="https://doi.org/10.1023/A:1008444502859">fail to take this into consideration</a>.” This observation is still true. </p>
<p><em>Phragmites</em> supports many animals, although somewhat fewer than <em>Spartina</em>, and performs other valuable services. In view of current concerns about sea level rise and marsh survival, I believe killing it everywhere is impractical and expensive, hurts sensitive species and wastes resources. </p>
<p>In my view, the preferred approach should shift away from trying to eradicate <em>Phragmites</em> wherever it appears. A better approach would emphasize modifying stands of it to create habitat for particular species while maintaining its other valuable functions.</p><img src="https://counter.theconversation.com/content/111162/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Judith Weis received funding from the National Science Foundation and the Meadowlands Environmental Research Institute.</span></em></p>Phragmites australis, an invasive reed, has taken over wetlands across the US. But it also stabilizes shorelines and harbors many fish and birds. Is it time to compromise with this alien?Judith Weis, Professor Emerita of Biological Sciences, Rutgers University - NewarkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1130202019-03-06T19:06:56Z2019-03-06T19:06:56ZRising seas allow coastal wetlands to store more carbon<figure><img src="https://images.theconversation.com/files/262335/original/file-20190306-48417-1mvzgzg.jpg?ixlib=rb-1.1.0&rect=0%2C674%2C5362%2C2600&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Carbon storage in Australian mangroves can help mitigate climate change.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/tidal-mangove-avicennia-marina-exposed-root-1078805684">Shutterstock</a></span></figcaption></figure><p>Coastal wetlands don’t cover much global area but they punch well above their carbon weight by sequestering the most atmospheric carbon dioxide of all natural ecosystems. </p>
<p>Termed “blue carbon ecosystems” by virtue of their connection to the sea, the salty, oxygen-depleted soils in which wetlands grow are ideal for burying and storing organic carbon.</p>
<p>In our research, <a href="https://www.nature.com/articles/s41586-019-0951-7">published today in Nature</a>, we found that carbon storage by coastal wetlands is linked to sea-level rise. Our findings suggest as sea levels rise, these wetlands can help mitigate climate change. </p>
<h2>Sea-level rise benefits coastal wetlands</h2>
<p>We looked at how changing sea levels over the past few millennia has affected coastal wetlands (mostly mangroves and saltmarshes). We found they adapt to rising sea levels by increasing the height of their soil layers, capturing mineral sediment and accumulating dense root material. Much of this is carbon-rich material, which means rising sea levels prompt the wetlands to store even more carbon.</p>
<p>We investigated how saltmarshes have responded to variations in “relative sea level” over the past few millennia. (Relative sea level is the position of the water’s edge in relation to the land rather than the total volume of water within the ocean, which is called the eustatic sea level.)</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mangrove-forests-can-rebound-thanks-to-climate-change-its-an-opportunity-we-must-take-102823">Mangrove forests can rebound thanks to climate change – it's an opportunity we must take</a>
</strong>
</em>
</p>
<hr>
<h2>What does past sea-level rise tell us?</h2>
<p>Global variation in the rate of sea-level rise over the past 6,000 years is largely related to the proximity of coastlines to ice sheets that extended over high northern latitudes during the last glacial period, some <a href="http://science.sciencemag.org/content/325/5941/710?casa_token=G3tt4MrUl_sAAAAA:WiQuy6HmXSyxn62lBNAOJz_C6zn4J4uWiuy7m8bhstVLvncY1rbNR7rOiJeh-ZkG8dB7Hs3tN-Umams">26,000 years ago</a>. </p>
<p>As ice sheets melted, northern continents slowly adjusted elevation in relation to the ocean due to flexure of the Earth’s mantle. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/262345/original/file-20190306-48432-533mrk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/262345/original/file-20190306-48432-533mrk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/262345/original/file-20190306-48432-533mrk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/262345/original/file-20190306-48432-533mrk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/262345/original/file-20190306-48432-533mrk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/262345/original/file-20190306-48432-533mrk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/262345/original/file-20190306-48432-533mrk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/262345/original/file-20190306-48432-533mrk.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">Karaaf Wetlands in Victoria, Australia.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/boobook48/16925355497/">Boobook48/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>For much of North America and Europe, this has resulted in a gradual rise in relative sea level over the past few thousand years. By contrast, the southern continents of Australia, South America and Africa were less affected by glacial ice sheets, and sea-level history on these coastlines more closely reflects ocean surface “eustatic” trends, which stabilised over this period.</p>
<p>Our analysis of carbon stored in more than 300 saltmarshes across six continents showed that coastlines subject to consistent relative sea-level rise over the past 6,000 years had, on average, two to four times more carbon in the upper 20cm of sediment, and five to nine times more carbon in the lower 50-100cm of sediment, compared with saltmarshes on coastlines where sea level was more stable over the same period. </p>
<p>In other words, on coastlines where sea level is rising, organic carbon is more efficiently buried as the wetland grows and carbon is stored safely below the surface.</p>
<h2>Give wetlands more space</h2>
<p>We propose that the difference in saltmarsh carbon storage in wetlands of the southern hemisphere and the North Atlantic is related to “accommodation space”: the space available for a wetland to store mineral and organic sediments. </p>
<p>Coastal wetlands live within the upper portion of the intertidal zone, roughly between mean sea level and the upper limit of high tide. </p>
<p>These tidal boundaries define where coastal wetlands can store mineral and organic material. As mineral and organic material accumulates within this zone it creates layers, raising the ground of the wetlands.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/262352/original/file-20190306-48438-1afjlpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/262352/original/file-20190306-48438-1afjlpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/262352/original/file-20190306-48438-1afjlpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/262352/original/file-20190306-48438-1afjlpu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/262352/original/file-20190306-48438-1afjlpu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/262352/original/file-20190306-48438-1afjlpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/262352/original/file-20190306-48438-1afjlpu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/262352/original/file-20190306-48438-1afjlpu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&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 coastal wetlands of Broome, Western Australia.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/north-west-city-broome-western-australia-616664939">Shutterstock</a></span>
</figcaption>
</figure>
<p>New accommodation space for storage of carbon is therefore created when the sea is rising, as has happened on many shorelines of the North Atlantic Ocean over the past 6,000 years.</p>
<p>To confirm this theory we analysed changes in carbon storage within a unique wetland that has experienced rapid relative sea-level rise over the past 30 years. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/without-wetlands-what-will-protect-the-great-barrier-reef-13239">Without wetlands, what will protect the Great Barrier Reef?</a>
</strong>
</em>
</p>
<hr>
<p>When underground mine supports were removed from a coal mine under Lake Macquarie in southeastern Australia in the 1980s, the shoreline subsided a metre in a matter of months, causing a relative rise in sea level.</p>
<p>Following this the rate of mineral accumulation doubled, and the rate of organic accumulation increased fourfold, with much of the organic material being carbon. The result suggests that sea-level rise over the coming decades might transform our relatively low-carbon southern hemisphere marshes into carbon sequestration hot-spots.</p>
<h2>How to help coastal wetlands</h2>
<p>The coastlines of Africa, Australia, China and South America, where stable sea levels over the past few millennia have constrained accommodation space, contain about <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5515097/">half of the world’s saltmarshes</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/262360/original/file-20190306-48432-1es4olt.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/262360/original/file-20190306-48432-1es4olt.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/262360/original/file-20190306-48432-1es4olt.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=264&fit=crop&dpr=1 600w, https://images.theconversation.com/files/262360/original/file-20190306-48432-1es4olt.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=264&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/262360/original/file-20190306-48432-1es4olt.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=264&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/262360/original/file-20190306-48432-1es4olt.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=331&fit=crop&dpr=1 754w, https://images.theconversation.com/files/262360/original/file-20190306-48432-1es4olt.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=331&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/262360/original/file-20190306-48432-1es4olt.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=331&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Saltmarsh on the shores of Westernport Bay in Victoria.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>A doubling of carbon sequestration in these wetlands, we’ve estimated, could remove an extra 5 million tonnes of CO₂ from the atmosphere per year. However, this potential benefit is compromised by the ongoing clearance and reclamation of these wetlands.</p>
<p>Preserving coastal wetlands is critical. Some coastal areas around the world have been cut off from tides to lessen floods, but restoring this connection will promote coastal wetlands – which also reduce the effects of floods – and carbon capture, as well as increase biodiversity and fisheries production. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/as-communities-rebuild-after-hurricanes-study-shows-wetlands-can-significantly-reduce-property-damage-83935">As communities rebuild after hurricanes, study shows wetlands can significantly reduce property damage</a>
</strong>
</em>
</p>
<hr>
<p>In some cases, planning for future wetland expansion will mean restricting coastal developments, however these decisions will provide returns in terms of avoided nuisance flooding as the sea rises. </p>
<p>Finally, the increased carbon storage will help mitigate climate change. Wetlands store flood water, buffer the coast from storms, cycle nutrients through the ecosystem and provided vital sea and land habitat. They are precious, and worth protecting. </p>
<hr>
<p><em>The authors would like to acknowledge the contribution of their colleagues, Janine Adams, Lisa Schile-Beers and Colin Woodroffe.</em></p><img src="https://counter.theconversation.com/content/113020/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kerrylee Rogers receives funding from the Australian Research Council, AINSE and the UOW Global Challenges Program.
</span></em></p><p class="fine-print"><em><span>Jeffrey Kelleway and Neil Saintilan do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>One surprising potential benefit of sea-level rise is it helps coastal wetlands store more carbon.Kerrylee Rogers, Associate Professor, University of WollongongJeffrey Kelleway, Postdoctoral Research Fellow in Environmental Sciences, Macquarie UniversityNeil Saintilan, Head, Department of Environmental Science, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1108492019-01-31T11:43:09Z2019-01-31T11:43:09ZWhat good are wetlands? 5 essential reads<figure><img src="https://images.theconversation.com/files/311643/original/file-20200123-162199-d4go5u.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5997%2C3998&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Wetlands are feeding, nesting and breeding sites for migratory birds, such as these sandhill cranes in Minnesota.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/21rAgqU">USFWS/Kris Spaeth</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p><em>World Wetlands Day on Feb. 2 marks the date when 18 nations signed the <a href="https://www.ramsar.org/">Convention on Wetlands</a> in 1971, in the Iranian city of Ramsar on the shores of the Caspian Sea. Since that time, scientists have shown that wetlands provide many valuable services, from buffering coasts against floods to filtering water and storing carbon. As the Trump administration moves to <a href="https://www.nytimes.com/2020/01/22/climate/trump-environment-water.html">strip legal protection</a> from many U.S. streams and wetlands, we offer five articles from our archives describing the many benefits these water bodies provide.</em></p>
<h2>1. Soaking up floodwaters</h2>
<p>Wetlands line coasts in many parts of the world. They act as natural sponges that soak up floodwaters and absorb force from storm surges, protecting communities farther inland. </p>
<p>Working with Lloyds of London, researchers <a href="https://scholar.google.com/citations?user=GVgDNHUAAAAJ&hl=en">Siddharth Narayan</a> and <a href="https://scholar.google.com/citations?user=fLXCUREAAAAJ&hl=en">Michael Beck</a> sought to quantify the value of these functions. Using insurance industry storm-surge models, they calculated that during Hurricane Sandy in 2012, wetlands along the U.S. Atlantic coast prevented <a href="https://theconversation.com/protecting-wetlands-helps-communities-reduce-damage-from-hurricanes-and-storms-104670">more than US$625 million in direct property damage</a> by reducing storm surge. They also estimated that marshes in Barnegat Bay, New Jersey reduced annual losses from flooding during smaller storms by an average of 16%, and up to 70% in some locations.</p>
<p>Narayan and Beck see restoring wetlands as an effective way to make coastal communities more resilient against storms and flooding:</p>
<blockquote>
<p>“Across the United States, the Caribbean and Southeast Asia, coastal communities face a crucial question: Can they rebuild 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>
</blockquote>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/256460/original/file-20190130-110834-g5zogz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/256460/original/file-20190130-110834-g5zogz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/256460/original/file-20190130-110834-g5zogz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=588&fit=crop&dpr=1 600w, https://images.theconversation.com/files/256460/original/file-20190130-110834-g5zogz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=588&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/256460/original/file-20190130-110834-g5zogz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=588&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/256460/original/file-20190130-110834-g5zogz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=739&fit=crop&dpr=1 754w, https://images.theconversation.com/files/256460/original/file-20190130-110834-g5zogz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=739&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/256460/original/file-20190130-110834-g5zogz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=739&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Coastal wetlands can extend well inland, transitioning from saltwater to brackish and freshwater.</span>
<span class="attribution"><a class="source" href="https://www.epa.gov/sites/production/files/2015-04/watershed_illustration-large.jpg">EPA</a></span>
</figcaption>
</figure>
<h2>2. Carbon-rich mud</h2>
<p>Wetlands store large quantities of carbon in plant tissue and soils. But as climate expert <a href="https://fletcher.tufts.edu/people/william-moomaw">William Moomaw</a> and wetland scientists <a href="https://www.linkedin.com/in/gillian-davies-5b68083/">Gillian Davies</a> and <a href="https://www.csu.edu.au/research/ilws/team/profiles/members/max-finlayson">Max Finlayson</a> point out, no global climate change agreement calls for <a href="https://theconversation.com/what-the-world-needs-now-to-fight-climate-change-more-swamps-99198">protecting wetlands as a way to slow climate change</a>. And around the globe, wetlands are constantly being drained, diked and paved over. </p>
<p>In contrast, forest protection gets a special section in the <a href="https://theconversation.com/forests-gain-long-awaited-recognition-in-paris-climate-summit-52238">Paris climate agreement</a>, which offers developing countries incentives to protect and expand tropical forests as carbon sinks. Moomaw, Davies and Finlayson believe wetlands deserve equal attention:</p>
<blockquote>
<p>“In our view, instead of draining swamps and weakening protections, governments at all levels should take action immediately to conserve and restore wetlands as a climate strategy. Protecting the climate and avoiding climate-associated damage from storms, flooding and drought is a much higher use for wetlands than altering them for short-term economic gains.” </p>
</blockquote>
<h2>3. ‘Blue carbon’ banks</h2>
<p>Mangrove forests, which grow in saltwater in tropical regions, are especially effective at locking up “blue carbon” – so called to distinguish it from “green” carbon storage on land. Louisiana State University scientists <a href="https://scholar.google.com/citations?user=zxWjMn8AAAAJ&hl=en">Robert Twilley</a> and <a href="https://scholar.google.com/citations?user=tNMGbw0AAAAJ&hl=en">Andre Rovai</a> estimate that “the wood and soil of mangrove forests along the world’s coastlines <a href="https://theconversation.com/mapping-the-worlds-blue-carbon-hot-spots-in-coastal-mangrove-forests-105793">hold 3 billion metric tons of carbon</a> – more than tropical forests.”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/256461/original/file-20190130-108338-1pab6mx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/256461/original/file-20190130-108338-1pab6mx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/256461/original/file-20190130-108338-1pab6mx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/256461/original/file-20190130-108338-1pab6mx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/256461/original/file-20190130-108338-1pab6mx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/256461/original/file-20190130-108338-1pab6mx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/256461/original/file-20190130-108338-1pab6mx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/256461/original/file-20190130-108338-1pab6mx.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">Mangrove forest in wetlands of Lebak, Sultan Kudarat, Philippines.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Lebak_Mangrove_01.JPG">Bonvallite/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Coastal development is an enormous threat to mangroves, whether for vacation homes in Florida or aquaculture farms in Asia. Twilley and Rovai wanted to pinpoint what type of mangroves were the most effective at storing carbon. By comparing conditions in different settings where mangroves flourish, they determined that river deltas and estuaries offer the best conditions for mangrove growth and carbon uptake:</p>
<blockquote>
<p>“Overall, mangroves in deltaic coasts such as the Mississippi River delta, the Amazon in Brazil and the Sundarbans in India and Bangladesh can sequester more carbon yearly than any other aquatic or terrestrial ecosystem on the globe. These are the world’s blue carbon hot spots.”</p>
</blockquote>
<h2>4. Mangroves versus marshes</h2>
<p>Mangroves are actually benefiting from climate change in some regions, such as Florida and the Gulf of Mexico. Villanova University biologist <a href="https://scholar.google.com/citations?user=91UF79cAAAAJ&hl=en">Samantha Chapman</a> has found that mangroves are <a href="https://theconversation.com/mangroves-protect-coastlines-store-carbon-and-are-expanding-with-climate-change-81445">becoming more abundant</a> in these areas, moving into zones formerly dominated by salt marshes, which typically are found in cooler zones. </p>
<p>Mangroves protect coasts more effectively against large waves, so this change isn’t necessarily harmful. However, as Chapman says, </p>
<blockquote>
<p>“It is important to note that marsh plants provide important habitats for numerous species of birds and fish. We don’t yet know how these animals will fare as mangroves replace marshes, nor do we yet understand other downsides of plant range shifts due to climate change.”</p>
</blockquote>
<p>Moreover, she notes, mangroves are not building new shoreline quickly enough to keep up with sea level rise in all locations. As her findings show, there is still much to learn about how climate change will affect different types of wetlands in various locations. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/SBbzz3TyFm8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The Trump administration’s changes will limit protection to large bodies of water, rivers that drain into them and some nearby wetlands, leaving many other waters unprotected from pollution or development.</span></figcaption>
</figure>
<h2>5. Small streams, big roles</h2>
<p>Wetlands aren’t just found along the coasts. Many major rivers, such as the Colorado and the Mississippi, start as networks of small streams, some of which may flow only during certain seasons or when it rains. But as Colorado State University geoscientist <a href="https://scholar.google.com/citations?user=MAHbIAIAAAAJ&hl=en">Ellen Wohl</a> explains, <a href="https://theconversation.com/small-streams-and-wetlands-are-key-parts-of-river-networks-heres-why-they-need-protection-110342">a lot happens in these small tributaries and isolated wetlands</a> that affects the larger rivers downstream:</p>
<blockquote>
<p>“Marvelously adapted organisms in dry streams wait for periods when life-giving water flows in. When the water comes, these creatures burst into action. … Amphibians move down from forests to temporarily flooded vernal wetlands to breed. Tiny fish, such as brassy minnows … speed through breeding and laying eggs that then grow into mature fish in a short period of time.”</p>
</blockquote>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/256463/original/file-20190130-75085-zq6jxi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/256463/original/file-20190130-75085-zq6jxi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/256463/original/file-20190130-75085-zq6jxi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/256463/original/file-20190130-75085-zq6jxi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/256463/original/file-20190130-75085-zq6jxi.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/256463/original/file-20190130-75085-zq6jxi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/256463/original/file-20190130-75085-zq6jxi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/256463/original/file-20190130-75085-zq6jxi.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"></a>
<figcaption>
<span class="caption">Brassy minnows, found throughout the northern U.S. and Canada, live in cool, slow-moving streams, creeks, overflow ponds near rivers, boggy lakes and ditches.</span>
<span class="attribution"><span class="source">Ellen Wohl</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Small channels in river networks also harbor microbes that are very good at removing contaminants from the water. And these channels slow down heavy rainfalls, allowing water to soak into the ground and reducing the risk of flooding downstream.</p>
<p>Eliminating federal protection for many of these small streams and wetlands, Wohl contends, “will strip rivers of their ability to provide water clean enough to support life, and will enhance the spiral of increasingly damaging floods that is already occurring nationwide.” </p>
<p><em>Editor’s note: This story is a roundup of articles from The Conversation’s archives.</em></p><img src="https://counter.theconversation.com/content/110849/count.gif" alt="The Conversation" width="1" height="1" />
The Trump administration is sharply reducing environmental protection for wetlands and streams across the US. This roundup of stories spotlights the many benefits that such water bodies provide.Jennifer Weeks, Senior Environment + Cities Editor, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1057932019-01-11T11:46:45Z2019-01-11T11:46:45ZMapping the world’s ‘blue carbon’ hot spots in coastal mangrove forests<figure><img src="https://images.theconversation.com/files/253317/original/file-20190110-43541-l4uqns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mangrove forest in Pichavaram, Tamil Nadu, India.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Pichavaram_Mangrove.jpg">VasuVR/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Human actions have boosted carbon dioxide concentrations in the atmosphere to levels <a href="https://nca2014.globalchange.gov/">higher than any measured over the last 160,000 years</a>. Rising concern over the risk of severe impacts from climate change is spurring research into ways in which ecosystems may mitigate global warming by storing excess carbon in plants and soil. </p>
<p><a href="http://www.oceanography.lsu.edu/twilleylab/TResearch.html">Our research group</a> has studied the ecology of mangroves for <a href="https://www.springer.com/us/book/9783319622040">over 40 years</a>. Mangroves are tropical forests that thrive in salt water, forming a canopy with the atmosphere and extensive roots in the sediment of the intertidal zone – the area that is above water at low tide and underwater at high tide. Scientists refer to them as “blue” carbon ecosystems, in contrast to “green” carbon ecosystems on land, such as forests and grasslands.</p>
<p>In a recent study, we estimated that the wood and soil of mangrove forests along the world’s coastlines hold <a href="https://doi.org/10.1002/fee.193">3 billion metric tons of carbon</a> – more than tropical forests. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/253318/original/file-20190110-43525-xovdsr.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253318/original/file-20190110-43525-xovdsr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253318/original/file-20190110-43525-xovdsr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253318/original/file-20190110-43525-xovdsr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253318/original/file-20190110-43525-xovdsr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253318/original/file-20190110-43525-xovdsr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253318/original/file-20190110-43525-xovdsr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253318/original/file-20190110-43525-xovdsr.png?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"></a>
<figcaption>
<span class="caption">Mangroves are common along tropical and subtropical coastlines around the world, and among the most biologically important systems on the planet.</span>
<span class="attribution"><a class="source" href="https://earthobservatory.nasa.gov/images/47427/mapping-mangroves-by-satellite">NASA Earth Observatory</a></span>
</figcaption>
</figure>
<p>We have also shown that previous studies have <a href="https://doi.org/10.1038/s41558-018-0162-5">overestimated blue carbon storage</a> in some river delta areas, such as the Amazon in Brazil; the Sundarbans region in India, where the Ganges, Brahmaputra and Meghna rivers converge; the Zambezi delta in Mozambique; and the Indus river delta in Pakistan. Others have grossly underestimated blue carbon storage in carbonate (peat-dominated) coastlines, such as Belize, the Florida Keys, Puerto Rico, Mexico’s Yucatan, Cuba, the Dominican Republic and several Caribbean islands. </p>
<p>The key to improving these estimates, we found, is to factor in how rivers, tides, waves and climate shape coastal landforms to create different environmental settings. Using this approach, we have produced a more accurate estimate of global blue carbon “hot spots” – an important first step toward protecting them.</p>
<h2>Adapted to many settings</h2>
<p>Mangroves can extend along tropical shorelines to <a href="https://theconversation.com/mangroves-protect-coastlines-store-carbon-and-are-expanding-with-climate-change-81445">the very edge of warm temperate climate zones</a>, controlled by changing frequency of frosts. They grow where tides and salt from oceans meet rivers carrying sediments from continents, mixing to form different types of intertidal zones. </p>
<p>Deltas exist where large rivers with very turbid waters and very little salt deliver sediment to the coast, forming extensive mud banks. In contrast, lagoons and coasts formed mainly of carbonate rock, such as chalk or limestone, have beautiful blue salty waters and firm sandy or coraline sediment along shorelines. In a middle category, estuaries form where rivers meet the sea and tides mix fresh and salt waters, forming brackish water that changes seasonally as river levels rise and fall. </p>
<p>Mangroves grow very differently in these various settings. In deltas, some of the largest mangrove trees in the world reach the heights of rain forests, with extensive roots penetrating into soft silty mud. In contrast, mangrove trees growing in the sediments of a carbonate shoreline are so much smaller that they look stunted, like ornamental trees in public parks. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/253328/original/file-20190110-43517-ah901x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253328/original/file-20190110-43517-ah901x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253328/original/file-20190110-43517-ah901x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253328/original/file-20190110-43517-ah901x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253328/original/file-20190110-43517-ah901x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253328/original/file-20190110-43517-ah901x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253328/original/file-20190110-43517-ah901x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253328/original/file-20190110-43517-ah901x.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"></a>
<figcaption>
<span class="caption">Grunts and other fish shelter among mangrove roots, U.S. Virgin islands.</span>
<span class="attribution"><a class="source" href="https://www.usgs.gov/media/images/grunts-and-other-fish-species-mangroves">USGS/Caroline Rogers</a></span>
</figcaption>
</figure>
<h2>Carbon stocks in coastal environmental settings</h2>
<p>Why do mangrove trees grow so differently in different environments? In our view, the explanation lies in how climate, rivers, tides and waves form conditions for mangrove tree growth. </p>
<p>The mud in deltas and estuaries with large tides contains high concentrations of essential nutrients. This creates benign environments where trees grow to their full potential. In contrast, coastlines where sediments are made of carbonate and tides are small tend to be nutrient-poor. This stunts tree growth and produces scrub forests along the shore. </p>
<p>As mangrove trees grow, they store carbon from the atmosphere in their wood. More carbon builds up in mangrove soils with the accumulation of organic matter, such as dead leaves and branches. We wanted to know whether the ecological conditions that control mangrove growth in different settings could also indicate how much blue carbon these ecosystems accumulate over their lifetime, or how much carbon they sequester each year. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Odz_2ZzYVLI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">On average, mangroves can store three to five times more carbon than upland tropical forests, mostly in soil.</span></figcaption>
</figure>
<h2>Annual carbon sequestration by mangroves</h2>
<p>There is no question that mangrove wood and soils around the world have accumulated significant quantities of carbon since they started to grow. Mean values range from 50 metric tons of carbon per acre (125 metric tons per hectare) in delta settings to as much as 220 metric tons per acre (550 metric tons per hectare) in carbonate coastlines. </p>
<p>For the purpose of curbing climate change, the most important question is how much carbon an ecosystem sequesters each year, mitigating carbon emissions produced from human activities such as burning fossil fuels. Carbon sequestration by mangrove forests is the amount of carbon that accumulates in wood or soils each year and remains stockpiled there, isolated from the atmosphere. In total, the world’s mangroves sequester approximately 24 million metric tons of carbon in soil per year. A mangrove forest on the Pacific island of Kosrae, in Micronesia, can store as much carbon annually as a tropical rain forest in Panama. </p>
<p>Our review found very significant differences in the rate of carbon uptake by different types of mangrove forests. Mangrove soils in the intertidal zone gain elevation as sediments are deposited each year. Coastal zones with major rivers have some of the highest rates of soil formation, so they also have high annual carbon sequestration rates. Since mangrove trees grow taller in these more benign delta environments, they also sequester more carbon in their wood each year. </p>
<p>Overall, mangroves in deltaic coasts such as the Mississippi River delta, the Amazon in Brazil and the Sundarbans in India and Bangladesh can sequester more carbon yearly than any other aquatic or terrestrial ecosystem on the globe. These are the world’s blue carbon hot spots.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/kkudKF4KR8g?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">In the town of Pajaritos in western Mexico, the government is paying fishermen to help restore mangroves destroyed by logging, tourism and bad fishing practices.</span></figcaption>
</figure>
<p>However it is important to distinguish between carbon density in mangrove soils – the amount of carbon stored per unit area – and carbon sequestration, which is the amount of carbon that accumulates in that same area per year. Carbon sequestration is enhanced in deltaic environments because rivers continuously deposit sediment in mangrove soils. This leads to higher burial rates of carbon, both from the trees themselves and from carbon carried by the rivers. </p>
<p>Delta soils also contain a lot of mineral sediment (rock), so they have a relatively low carbon content by volume. In contrast, in carbonate settings such as Caribbean islands, most of the soil volume is made up of plant roots, so it has a higher carbon content. But soil builds up in deltas more quickly, since rivers are always depositing new sediment. </p>
<p>This distinction is important for conservation strategies. Destroying mangrove forests to build roads, shrimp ponds or other commercial projects can release significant quantities of carbon to the atmosphere – even in carbonate settings, since so much of the soil there consists of plant material. This makes it important to conserve mangroves in all types of settings. </p>
<p>It also is very important to restore mangroves, particularly in deltaic regions, where they can increase those ecosystems’ capacity to clean the atmosphere of existing carbon dioxide. By improving our understanding of how mangroves function under different conditions, we can safeguard and increase these valuable blue carbon stores.</p><img src="https://counter.theconversation.com/content/105793/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Twilley receives funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Andre Rovai receives funding from Louisiana Sea Grant. </span></em></p>Mangrove forests along the world’s tropical and subtropical coasts store enormous quantities of ‘blue’ carbon – especially in river delta zones, where soil builds up quickly.Robert Twilley, Professor of Oceanography and Coastal Science and Executive Director, Louisiana Sea Grant, Louisiana State University Andre Rovai, Postdoctoral Fellow, Louisiana State University Licensed as Creative Commons – attribution, no derivatives.