Green Cities

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GUEST OBSERVATION
You may mock the national anthem by singing “Our land abounds in nature strips” but what you might not know is how true that is.
In Melbourne, for example, <a href="https://www.sciencedirect.com/science/article/pii/S1618866719300718" target="_blank">more than a third of all public green space is nature strips</a>. (That figure includes roundabouts, medians and other green bits of the street.)
That’s a remarkable amount. The nature strip is everywhere. A million small patches combine into a giant park spanning the city, making it a significant player in our urban ecosystems.
A second remarkable thing is that the nature strip is <a href="https://apo.org.au/sites/default/files/resource-files/2007/11/apo-nid60258-1105966.pdf" target="_blank">public land that private citizens are required by law to maintain</a>. Councils manage the trees, but we residents mow the lawn.
What are the rules on nature strips?
<a href="https://images.theconversation.com/files/296146/original/file-20191009-3872-1i673y4.JPG?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/296146/original/file-20191009-3872-1i673y4.JPG?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=237&amp;fit=clip" alt=""></a>
Succulents, Agapanthus and Gazanias are the most common plantings on nature strips. Adrian Marshall CC BY 4.0, Author provided
Many residents go further and plant a street tree or some garden plants – succulents, Agapanthus and Gazanias are the most common. But the chances are that, whatever the garden on the nature strip, it’s against the rules.
The rules on nature strips vary from council to council. Some councils don’t allow any plantings. Others restrict plantings by height or allow only plants indigenous to the local area. In some areas, nature strips can only be planted to prevent erosion on steep slopes.
Some councils disallow food plants, for fear of historic lead contamination from leaded petrol. Others insist on no plants within a metre of the kerb and two metres of the footpath.
These bylaws are inconsistent and illogical. For instance, councils that insist on indigenous species nevertheless plant exotic street trees. Councils that say plants must be less than 30cm high to ensure they don’t block drivers’ sight lines still allow vehicles to park on the street, blocking sight lines.
Bylaws deny us many benefits
To have council bylaws restrict or disallow gardening in the nature strip flies in the face of common sense. Street greenery, whether it's trees, shrubs or lawn, provides many benefits. The science is in on this.
Urban wildlife uses street greenery for habitat and food and as green corridors for movement.
Even for those who mow, the lawns of nature strips are not just turf grass. They are home to over 150 species of plants, based on my yet-to-be-published survey data for nearly 50 neighbourhoods, confirming <a href="https://link.springer.com/article/10.1007/s11252-009-0098-7" target="_blank">earlier studies</a>. Many of these, like the clovers, provide important resources for pollinators.
One <a href="https://www.propertyobserver.com.au/https://www.nrs.fs.fed.us/pubs/55816" target="_blank">US study</a> showed that changing from a weekly mow to every three weeks increased the number of flowers in a lawn by 250%. Less mowing is good news for bees and butterflies.
An unpublished recent survey by the author and colleagues found gardening in the nature strip adds native plants to the streetscape, increases biodiversity and add structural complexity (more layers of plants, more types of stuff), which is important for many species.
<a href="https://images.theconversation.com/files/296397/original/file-20191010-188823-3m94cd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/296397/original/file-20191010-188823-3m94cd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt=""></a>
The greater the diversity of plantings, the greater the benefits a nature strip can provide. <a href="https://www.flickr.com/photos/tedxmelbourne/9642464172/in/photolist-hj8dyc-skaU1u-dREut-eJsU1F-ffLmZK-indYV3-cLiW2J-vB2sc-7NsaK4-4VkF3d-yGjbRF-beH7sn-6Y5uUZ-rxC4mN-6LgaCq-8uZkP8-fFMrYB-fFMzz6-959BCc-fFMqN6-9XyM3R-8uZkQZ-fG59Eh-fG55kj-MdakbU-zKkV6-9A3mjp-2hgzR2Y-2gLLfma-2gLM1dK-2gjDcaq-fG56q1-V4CxJS-2EepMw-AJYA3h-8PLEFM-2Nnv4q-3HCckP-8LfDb6-F9XHNG-fG5dib-9hzViT-d5L2G-fG57A5-7tQdTT-vh8B5S-2d9eEDd-2gtBYEp-fFMxhv-6tVDoj" target="_blank">TEDxMelbourne/Flickr</a>, <a href="http://creativecommons.org/licenses/by-nc-nd/4.0/" target="_blank">CC BY-NC-ND</a>
<a href="https://www.propertyobserver.com.au/https://pubag.nal.usda.gov/catalog/1135097" target="_blank">Street greenery helps</a> water <a href="https://www.propertyobserver.com.au/https://www.ncbi.nlm.nih.gov/pubmed/27094440" target="_blank">soak into the ground</a>, filtering out pollutants, recharging aquifers and making rivers healthier. It <a href="https://www.propertyobserver.com.au/https://www.ncbi.nlm.nih.gov/pubmed/26828172" target="_blank">cools streets</a> and <a href="https://www.sciencedirect.com/science/article/pii/S0169204614002503" target="_blank">helps counter the urban heat island effect</a>. It also <a href="https://www.sciencedirect.com/science/article/abs/pii/S0277953613003742" target="_blank">promotes a sense of community</a>, <a href="https://www.sciencedirect.com/science/article/pii/S2214140518303281" target="_blank">encourages walking</a> and lowers the incidence of <a href="https://www.sciencedirect.com/science/article/pii/S2214140518303281" target="_blank">heart disease</a>, <a href="https://www.propertyobserver.com.au/https://jamanetwork.com/journals/jama/fullarticle/2524191" target="_blank">diabetes</a>, <a href="https://theconversation.com/children-living-in-green-neighbourhoods-are-less-likely-to-develop-asthma-96190" target="_blank">asthma</a> and <a href="https://www.sciencedirect.com/science/article/pii/S0169204614002941" target="_blank">depression</a>.
But councils tend to be risk-averse. They worry they will be sued if someone trips on groundcover or stubs their toe on an out-of-place garden gnome.
Fortunately, this risk aversion isn’t universal. For instance, the <a href="https://www.vincent.wa.gov.au/residents/environment/environmental-sustainability/news-events/adopt-a-verge.aspx" target="_blank">City of Vincent</a> in Western Australia is so keen for residents to convert lawn to waterwise plantings that it will remove turf and provide native plants.
But, as climate change looms, stubbed toes are not the main risk we should be worrying about. Rather, we must urgently remake our cities and our culture for sustainability and resilience.
Gardening becomes a neighbourly act
One of the great things about gardening in the nature strip is that people are <a href="https://www.sciencedirect.com/science/article/pii/S1618866719302535" target="_blank">more likely to do it if their neighbours do it</a>. It’s contagious, a positive-feedback loop creating a greener street.
Our recent survey found residents who garden in the nature strip have a greater <a href="http://www.communityscience.com/news-detail.php?news=114" target="_blank">sense of community</a> than those who don’t.
<a href="https://images.theconversation.com/files/296997/original/file-20191015-98653-wopjbq.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/296997/original/file-20191015-98653-wopjbq.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt=""></a>
A well-designed street garden, fully covering the nature strip, allowing pedestrian access to cars and using indigenous plants. Adrian Marshall CC BY 4.0, Author provided
Interestingly, the benefits nature strips provide are <a href="https://www.sciencedirect.com/science/article/pii/S1618866719302535" target="_blank">not equally distributed across the city</a>. For instance, newer neighbourhoods have more nature strip than older neighbourhoods (though their trees are younger). People garden the nature strip more on minor roads than major roads, and in more socially advantaged neighbourhoods.
Almost a <a href="https://www.sciencedirect.com/science/article/pii/S1618866719302535" target="_blank">quarter of residential properties</a> in Melbourne have some sort of nature strip gardening. If councils were to encourage this activity we might achieve more street greening with little cost to our cash-strapped councils. Such encouragement would also free many residents of their sense of frustration at being required to maintain the nature strip but forbidden to do anything more than mow.
Given that more than a third of our public green space is nature strip, the many small actions of residents can add up to substantial positive change.<img src="https://counter.theconversation.com/content/124781/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1">
Adrian Marshall, Lecturer, Landscape Architecture and Urban Ecology, University of Melbourne.
This article is republished from <a href="http://theconversation.com" target="_blank">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/our-land-abounds-in-nature-strips-surely-we-can-do-more-than-mow-a-third-of-urban-green-space-124781" target="_blank">original article</a>.
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j.ballantyne1990-6AQqhLzZaK

Our land abounds in nature strips – surely we can do more than mow a third of urban green space

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GUEST OBSERVATION
Greening our cities has become one of the great <a href="https://newclimateeconomy.report/2018/wp-content/uploads/sites/6/2018/09/NCE_2018_FULL-REPORT.pdf" target="_blank">global imperatives</a> of the 21st century including to tackle climate change. And Australia’s sprawling car-based cities are gradually changing to embrace green or living infrastructure.
Green cities bring together elements of architectural design and urban planning, often combining plants and built infrastructure to meet the needs of humans, such as our <a href="https://en.wikipedia.org/wiki/Biophilia_hypothesis" target="_blank">love of nature</a>.
Trees, plants, waterways and wetlands can deliver climate conditioning, cooling cities by reducing the urban heat island effect. They also absorb carbon dioxide, filter wastewater and create habitats.
Living elements can be incorporated with built infrastructure at a range of scales, from individual buildings with green walls and roofs, through to citywide strategies. And there are a <a href="http://www.curf.com.au/files/view/?id=633" target="_blank">suite of strategies</a> to guide more widespread integration of biological elements and ecological processes in cities.
In recent months, we <a href="https://mainstreaminggreeninfrastructure.com/reports/Barbara%20Norman%20mainstreaming%20GI%20in%20Australia.pdf" target="_blank">profiled Australian examples of living infrastructure</a> that show some of Australia’s approaches to developing green infrastructure, from greening Melbourne’s laneways to Canberra’s urban forest. These cities are already redesigning their water systems and implementing urban forest strategies to create green belts and protect and restore waterways.
Melbourne and Canberra provide some useful examples of the green cities movement, but to make it mainstream, these techniques need to be adopted widely through policies supporting more holistic and better integrated urban planning.
Why we need urban forests
Percival Alfred Yeoman was one of the first Australian pioneers of urban forestry. In 1971, <a href="https://www.propertyobserver.com.au/https://trove.nla.gov.au/work/8870297?q&amp;versionId=12235056" target="_blank">he articulated</a> a clear vision for enhancing cities with trees.
Local governments in Adelaide, Brisbane, Melbourne and Sydney, are implementing his ideas, committing to <a href="https://202020vision.com.au/about-the-vision/" target="_blank">ambitious increases in urban canopy cover</a>. Their targets range from 25% to 40%.
This <a href="https://202020vision.com.au/the-network/" target="_blank">revived interest in urban forestry</a> comes from its well documented potential for accelerating the transition to more climate adaptive cities.
The social, environmental and economic benefits of urban trees, or “ecosystem services”, are becoming better recognised, including for their recreational and cultural values.
<h2>Melbourne and Canberra are leading Australia’s green cities movement</h2>
<h3>Melbourne</h3>
Melbourne has a rich legacy of urban parks and green belts thanks to planning decisions made in the city’s early years.
These parks underpin a new wave of urban greening, with projects that aim to deliver action on climate change, biodiversity and the health and well-being of communities.
The Melbourne green infrastructure <a href="https://www.melbourne.vic.gov.au/community/greening-the-city/green-infrastructure/Pages/green-infrastructure.aspx" target="_blank">plan</a> includes: 
<ul>
<li>a “<a href="http://www.growinggreenguide.org/" target="_blank">growing green guide</a>” that provides practical advice to community and business groups on planning, design and maintenance of green infrastructure </li>
<li>the <a href="http://www.melbourne.vic.gov.au/community/%20greening-the-city/green-infrastructure/Pages/greeninglaneways.%20aspx">greening laneways strategy</a>, which builds on the commercial revitalisation of Melbourne’s laneways over three decades. Laneways with greening potential were mapped and demonstration project developed to display techniques for making them more vibrant green spaces for business, tourists and locals to enjoy</li>
<li>an <a href="http://www.melbourne.vic.gov.au/community/parks-openspaces/%20urban-forest/Pages/urban-forest-strategy.aspx" target="_blank">urban forest strategy</a>, with an overall target of 40% canopy cover by 2040. And 5 to 8 million trees will be planted over coming decades for the greater Melbourne metropolis.</li>
</ul>
<iframe src="https://www.youtube.com/embed/RBtAUUzH7Uo?wmode=transparent&amp;start=0" frameborder="0" width="440" height="260"></iframe>
<h3>Canberra</h3>
Canberra is often described as “a city within a landscape” and the “bush capital”. But its higher altitude, hot dry summers and cold winters bring a set of challenges for green infrastructure.
With more than 800,000 planted trees, Canberra is an urban forest. But these trees require special care and attention given they are ageing and suffering from a hotter, drier climate.
Wildfire also represents a significant risk where urban and rural areas connect. This means Canberra needs urban forests that will cool the city in warmer months without also escalating wildfire risks.
The <a href="/news">ACT Government</a> has committed to action on climate change, legislating targets for 100% renewable electricity by 2020 and carbon neutrality (no net carbon emissions) by 2045.
Integrated approach needed to expand green cities
Greening cities requires a holistic approach – for instance, not leaving the health of waterways entirely to water engineers.
Greening cities is more than just a <a href="https://www.academia.edu/38053856/The_city_as_nature_and_the_nature_of_the_city_-_climate_adaptation_using_living_infrastructure_governance_and_integration_challenges" target="_blank">technical challenge</a>. Transforming the form and functions of urban systems, through urban forests and other living infrastructure, <a href="http://www.curf.com.au/files/view/?id=633" target="_blank">requires</a> greater leadership and political commitment, integrated planning and community participation, and long-term thinking.
An integrated approach to greening cities involves mapping diverse opportunities and mobilising support for change in the community. As an example, urban storm water can be a productive resource when used in constructed wetlands or to irrigate urban forests.
And often urban drainage lines and wastelands can be transformed into green spaces, but it’s worth recognising there is intense competition for space for housing.
But for more widespread adoption of integration, institutional support within local governments and metropolitan water and planning agencies is needed.
So to scale up living infrastructure in our urban landscapes, we must learn from local success stories, conduct more research, and better understand how to deal with climate adaptation and mitigation challenges.
Jason Alexandra, PhD candidate, RMIT University.
Jason Alexandra would like to gratefully acknowledge the contributions of Barbara Norman to this article.<img src="https://counter.theconversation.com/content/119933/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1">
This article is republished from <a href="http://theconversation.com" target="_blank">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/for-green-cities-to-become-mainstream-we-need-to-learn-from-local-success-stories-and-scale-up-119933" target="_blank">original article</a>.
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For green cities to become mainstream, we need to learn from local success stories and scale up

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EXPERT OBSERVER
Urgent and radical change in urban transport policies and practices will benefit the planet and future generations.
The UN Intergovernmental Panel on Climate Change recently warned that <a href="https://www.theguardian.com/environment/2018/oct/08/how-the-un-climate-panel-ipcc-got-to-15c-threshold-timeline" target="_blank">global warming could reach 1.5℃ as early as 2030</a>. The landmark <a href="http://www.ipcc.ch/report/sr15/">report</a> by leading scientists urged nations to do more to avert an impending crisis.
<a href="https://www.vox.com/2018/10/8/17948832/climate-change-global-warming-un-ipcc-report" target="_blank">We have 12 years</a>, the report said, to contain greenhouse gas emissions. This includes serious efforts to reduce transport emissions. 
In Australia, transport is the <a href="https://www.climatecouncil.org.au/resources/transport-fact-sheet/" target="_blank">third-largest source of greenhouse gases</a>, accounting for around <a href="/news">17% of emissions</a>. Passenger cars account for <a href="https://www.climatecouncil.org.au/resources/transport-fact-sheet/" target="_blank">around half of our transport emissions</a>.
The transport sector is also one of the strongest factors in emissions growth in Australia. Emissions from transport have <a href="/news">increased nearly 60% since 1990</a> – <a href="https://www.climatecouncil.org.au/resources/transport-fact-sheet/" target="_blank">more than any other sector</a>. Australia is ranked <a href="https://aceee.org/research-report/i1801" target="_blank">20th out of 25 of the largest energy-using countries for transport energy efficiency</a>.
Cities around the world have many opportunities to reduce emissions. But this requires renewed thinking and real commitment to change.
Our planet can’t survive our old transport habits
Past (and still current) practices in <a href="https://theconversation.com/australian-infrastructure-plan-has-some-way-to-go-to-give-our-cities-what-they-need-54954" target="_blank">urban and transport planning</a> are fundamental causes of the transport problems we face today.
Over the past half-century, cities worldwide have <a href="https://theconversation.com/density-sprawl-growth-how-australian-cities-have-changed-in-the-last-30-years-65870" target="_blank">grown rapidly, leading to urban sprawl</a>. The result was high demand for motorised transport and, in turn, increased emissions.
The traffic gridlock on roads and motorways was the catalyst for most transport policy responses during that period. The solution prescribed for most cities was to <a href="https://theconversation.com/stuck-in-traffic-we-need-a-smarter-approach-to-congestion-than-building-more-roads-84774" target="_blank">build out of congestion by providing more infrastructure for private vehicles</a>. Limited attention was given to <a href="https://theconversation.com/on-the-road-research-can-improve-transport-across-australia-43643" target="_blank">managing travel demand</a> or improving other modes of transport.
Equating mobility with building more roads nurtured a tendency towards increased motorisation, reinforcing an ever-increasing inclination to expand the road network. The result was a range of unintended adverse <a href="http://www.oecd.org/economy/rethinking-urban-sprawl-9789264189881-en.htm" target="_blank">environmental, social and economic consequences</a>. Most of these are rooted in the high priority given to private vehicles.
What are the opportunities to change?
The various strategies to move our cities in the right direction can be grouped into four broad categories: avoid, shift, share, and improve. Major policy, behaviour and technology changes are required to make these strategies work.
Avoid strategies aim to slow the growth of travel. They include initiatives to reduce trip lengths, such as <a href="https://theconversation.com/higher-density-and-diversity-apartments-are-australia-at-its-most-multicultural-97176" target="_blank">high-density</a> and <a href="https://theconversation.com/a-place-to-live-work-and-play-why-mixed-use-developments-are-making-a-comeback-73142" target="_blank">mixed land use developments</a>. Other options decrease private vehicle travel – for example, through car/ride sharing and <a href="https://www.gizmodo.com.au/2015/12/how-to-fix-traffic-congestion-in-australia/" target="_blank">congestion pricing</a>. And <a href="https://theconversation.com/go-forth-and-telework-but-will-it-work-for-you-10682" target="_blank">teleworking</a> and e-commerce help people avoid private car trips altogether.
Shanghai’s Hongqiao transport hub is a unique example of an <a href="https://uic.org/cdrom/2013/nextstation/doc/proceedings/3Ajianping.pdf" target="_blank">integrated air, rail and mixed land use development</a>. It combines Hongqiao’s airport, metro subway lines, and regional high-speed rail. A low-carbon residential and commercial <a href="https://www.usgbc.org/articles/building-shanghai-tomorrow-hongqiao-cbds-low-carbon-transportation-hub">precinct</a> surrounds the hub.
<a href="https://images.theconversation.com/files/246775/original/file-20181122-161609-x8oxhj.png?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/246775/original/file-20181122-161609-x8oxhj.png?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt=""></a>
Layout of Shanghai Hongqiao integrated transport hub.<a href="https://www.researchgate.net/figure/Layout-of-Shanghai-hongqiao-integrated-transport-hub-SHITH_fig1_309453749"> </a>
Shift strategies encourage travellers to switch from private vehicles to public transport, walking and cycling. This includes improving bus routes and service frequency.
<a href="https://theconversation.com/stuck-in-traffic-we-need-a-smarter-approach-to-congestion-than-building-more-roads-84774" target="_blank">Pricing strategies</a> that discourage private vehicles and encourage other modes of transport <a href="https://www.ted.com/talks/jonas_eliasson_how_to_solve_traffic_jams" target="_blank">can also be effective</a>. Policies that include <a href="https://www.theguardian.com/money/2018/jul/02/norway-electric-cars-subsidies-fossil-fuel" target="_blank">incentives</a> that make electric vehicles more affordable have been shown to encourage the shift.
Norway is an undisputed world leader in electric vehicle uptake. <a href="https://www.theguardian.com/environment/2017/dec/25/norway-leads-way-electric-cars-green-taxation-shift" target="_blank">Nearly a third of all new cars sold in 2017 were a plug-in model</a>. The electric vehicle market share was expected to be as much as 40% within a year.
An electric vehicle charging station in the Norwegian capital Oslo. <a href="https://www.shutterstock.com/image-photo/electric-car-charging-station-oslo-eco-670494520?irgwc=1&amp;utm_medium=Affiliate&amp;utm_campaign=TinEye&amp;utm_source=77643&amp;utm_term="> </a>
Share strategies affect car ownership. New sharing economy businesses are already moving people, goods and services. Shared mobility, rather than car ownership, is providing city dwellers with a real alternative.
This trend is likely to continue and will pose significant challenges to car ownership models.
Uber claims that its <a href="https://www.uber.com/en-IN/blog/mumbai/onestepforward-with-uberpool/" target="_blank">carpooling service in Mumbai</a> saved 936,000 litres of fuel and reduced greenhouse gas emissions by 2,662 metric tonnes within one year. It also reports that <a href="http://www.cityam.com/242760/uber-reveals-london-ride-sharing-figures-for-uberpool" target="_blank">UberPool in London</a> achieved a reduction of more than 1.1 million driving kilometres in just six months.
<img src="https://images.theconversation.com/files/244778/original/file-20181109-35554-ym7dj5.png?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="">
UberPool is available in inner Melbourne suburbs. Trip must begin and end in this area.
Improve strategies promote the use of technologies to optimise performance of transport modes and <a href="https://theconversation.com/intelligent-infrastructure-when-roads-and-vehicles-talk-to-each-other-7865" target="_blank">intelligent infrastructure</a>. These include <a href="https://www.weforum.org/agenda/2015/03/why-our-cities-need-smart-transport/" target="_blank">intelligent transport systems</a>, urban information technologies and emerging solutions such as <a href="https://www.itf-oecd.org/files/urban-mobility-system-upgrade" target="_blank">autonomous mobility</a>.
Our <a href="https://www.tandfonline.com/doi/abs/10.1080/23249935.2018.1528485?journalCode=ttra21" target="_blank">research</a> shows that sharing 80% of autonomous vehicles will reduce net emissions by up to 20%. The benefits increase with wider adoption of autonomous shared electric vehicles.
Autonomous vehicles can offer first- and last-kilometre solutions, especially in outer suburbs with limited public transport services. <a href="https://www.shutterstock.com/image-photo/iot-smart-automotive-driverless-car-artificial-794528215?irgwc=1&amp;utm_medium=Affiliate&amp;utm_campaign=TinEye&amp;utm_source=77643&amp;utm_term="> </a>
The urgency and benefits of steering our cities towards a path of low-carbon mobility are unmistakable. This was recognised in the past but progress has been slow. Today, the changing context for how we build future cities – smart, healthy and low-carbon – presents new opportunities.
If well planned and implemented, these four interventions will collectively achieve transport emission reduction targets. They will also improve access to the jobs and opportunities that are preconditions for sound economic development in cities around the world.<img src="https://counter.theconversation.com/content/106076/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1">
<a href="https://theconversation.com/profiles/hussein-dia-110689" target="_blank">Hussein Dia</a>, Chair, Department of Civil and Construction Engineering, <a href="http://theconversation.com/institutions/swinburne-university-of-technology-767" target="_blank">Swinburne University of Technology</a>
This article is republished from <a href="http://theconversation.com" target="_blank">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/four-ways-our-cities-can-cut-transport-emissions-in-a-hurry-avoid-shift-share-and-improve-106076" target="_blank">original article</a>.
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Four ways our cities can cut transport emissions in a hurry

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Population growth has seen skylines creep ever higher and entire cities rise from ocean depths. The latest “ocean city” is the Chinese-developed <a href="https://cgpvforestcity.wordpress.com/category/press-release/" target="_blank">Forest City project</a>. By 2045, four artificial islands in Malaysia will cover 14km² of ocean (an area larger than 10,000 Olympic swimming pools), and support 700,000 residents.
Often overlooked, however, is the damage that artificial islands can cause to vital seafloor ecosystems. But it doesn’t have to be this way. If proper planning and science are integrated, we can develop the design strategies that will help build the “blue-green” ocean cities of tomorrow.
Colonising the ocean frontier
Ever growing numbers of human-made structures are <a href="https://theconversation.com/concrete-coastlines-its-time-to-tackle-our-marine-urban-sprawl-38175" target="_blank">occupying our oceans</a>. Cities built on artificial islands in the ocean are providing a solution for urban planners trying to manage the population squeeze.
And yet, so-called “<a href="https://www.propertyobserver.com.au/https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/110246?af=R" target="_blank">ocean sprawl</a>” dates as far back as <a href="http://www1.frm.utn.edu.ar/laboratorio_hidraulica/Biblioteca_Virtual/Coastal%20Engineering%20Manual%20-%20Part%20I/Part_I-Chap_3entire.pdf" target="_blank">Ancient Egypt</a>. Over the past few centuries, artificial islands have been built through land reclamation. Land reclamation is the process of creating new land from existing water bodies.
<img src="https://images.theconversation.com/files/211671/original/file-20180323-54878-1a6j7pa.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="">
Atlantis, The Palm Hotel in Dubai, United Arab Emirates is built on an entirely artificial island. Shutterstock
The Netherlands, for instance, has been draining lakes and expanding its coastline to <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/ird.340" target="_blank">fight the advance of the sea</a> since the 1500s. The Dutch actually built one of the first and largest artificial islands, which is <a href="https://www.tourism-review.com/travel-tourism-magazine-flevoland-worlds-largest-artificial-island--article2372" target="_blank">now home to some 400,000 people</a>. Japan’s third-busiest airport, the <a href="https://www.kansai-airport.or.jp/en/" target="_blank">Kansai International Airport</a>, was built on an artificial island in 1994. China has also been building into the oceans, reclaiming <a href="https://www.sciencedirect.com/science/article/pii/S0964569114000696" target="_blank">more than 13,000km² of seafloor</a> and an estimated <a href="https://www.propertyobserver.com.au/https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1890/130260" target="_blank">65% of tidal habitat</a> since the 1950s.
<img src="https://images.theconversation.com/files/211672/original/file-20180323-54881-j4i3c.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=237&amp;fit=clip" alt="">
The artificial Eden Island in Mahe, Seychelles. Shutterstock
Using Google maps, we were able to identify more than 450 artificial islands around the world, including the famous Palm Islands of Dubai. These are often celebrated as <a href="https://www.iveyengineering.com/modern-engineering-marvels/" target="_blank">engineering marvels</a>, but at what cost to the marine environment?
<h2>We can’t ignore what lies beneath</h2>
Marine habitats have always been essential for human life in coastal regions. They provide food, building and crafting materials, and less-known services such as <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/10-1510.1" target="_blank">coastal protection, nutrient cycling and pollution filtration</a>.
<img src="https://images.theconversation.com/files/211673/original/file-20180323-54884-1t8t6ao.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=237&amp;fit=clip" alt="">
One of the World Map islands in Dubai, United Arab Emirates. Shutterstock
The creation of artificial islands causes <a href="https://www.sciencedirect.com/science/article/pii/S0022098117300606" target="_blank">large changes to the seabed</a> by permanently smothering local habitats. In many parts of the world, existing habitats provide the foundation for artificial island construction. For instance, artificial islands in the tropics are often built directly on top of coral reefs. This leads to considerable destruction of already threatened ecosystems.
Land reclamation also impacts nearby habitats that are particularly sensitive to murky waters, such as coral reefs and seagrass beds. In Singapore, land reclamation is associated with <a href="https://www.researchgate.net/profile/L_Chou/publication/285088156_Response_of_Singapore_reefs_to_land_reclamation/links/569c63b008aea1476954792e.pdf" target="_blank">coral reef decline due to sedimentation and resulting light reductions</a>. Singapore has lost <a href="https://www.sciencedirect.com/science/article/pii/S096456911400355X" target="_blank">nearly 45% of the country’s intertidal reef flats and almost 40% of intertidal mudflats</a>.
When the ecological, economic, and social value of marine habitats are considered, artificial islands and ocean sprawl seem to be indulgences that we cannot afford. The effects would be akin to the suburban sprawl of the 20th century. To avoid this cost, we need to address the complexities of the underwater world in urban planning and development.
<h2>“Blue urbanism”</h2>
In his book <a href="http://blueurbanism.org/blue-urbanism-cities-and-oceans-together/" target="_blank">Blue Urbanism</a>, Timothy Beatley calls for urban planners to consider and value ocean ecosystems. He argues that we need to recognise the <a href="http://bigthink.com/articles/need-a-nature-break-why-blue-is-the-new-green-for-stress-relief">psychological value of human connections to blue space</a>, and extend green practices on land into marine environments. While some artificial island developments such as the Forest City project are touted as “eco-cities”, more could be done both to minimise impacts below the waterline and integrate underwater environments into city life.
Why not combine a “Forest City” with the principles of a “<a href="https://theconversation.com/chinas-sponge-cities-aim-to-re-use-70-of-rainwater-heres-how-83327">Sponge City</a>”? While native plantings in a forest city could help to reduce air pollution, sponge cities seek to “absorb” and reuse rainwater, thus reducing pollution entering the oceans through <a href="https://theconversation.com/massive-storms-are-pumping-pollution-into-our-oceans-time-to-clean-up-our-cities-60551">stormwater runoff</a>. Around artificial islands, developers could also embrace the <a href="https://www.scapestudio.com/projects/oyster-tecture/" target="_blank">water filtration powerhouse</a> of the oceans: active oyster reefs.
The location of future constructions should also be carefully evaluated to ensure the preservation of important marine habitats. Artificial islands have the potential to create <a href="https://theconversation.com/our-oceans-are-out-of-balance-can-we-learn-some-tips-from-feng-shui-64975" target="_blank">fragmented seascapes</a>, but with careful spatial planning and smart designs, they could create corridors for some <a href="https://mashable.com/2015/06/01/global-warming-huge-oceans-shift/#66PBDFJxyuq4" target="_blank">climate migrants</a> or those threatened species most at risk from habitat loss.
<img src="https://counter.theconversation.com/content/93843/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1">Designs based on ecological principles can reduce the impacts of artificial islands on natural habitats. However, applications of “blue-green” infrastructure remain largely untested at large scales. New designs, building strategies and spatial planning that integrate seascapes and landscapes are an opportunity for both “smarter” cities and experimentation for the development of successful blue-green technologies.
<a href="https://theconversation.com/profiles/katherine-dafforn-155892" target="_blank">Katherine Dafforn</a>, Senior Research Associate in Marine Ecology, <a href="http://theconversation.com/institutions/unsw-1414" target="_blank">UNSW</a>; <a href="https://theconversation.com/profiles/ana-bugnot-159810" target="_blank">Ana Bugnot</a>, Research Associate, <a href="http://theconversation.com/institutions/unsw-1414" target="_blank">UNSW</a>; <a href="https://theconversation.com/profiles/eliza-heery-455058" target="_blank">Eliza Heery</a>, Research Fellow in Marine Ecology, <a href="http://theconversation.com/institutions/national-university-of-singapore-998" target="_blank">National University of Singapore</a>, and <a href="https://theconversation.com/profiles/mariana-mayer-pinto-155512" target="_blank">Mariana Mayer-Pinto</a>, Senior Research Associate in marine ecology, <a href="http://theconversation.com/institutions/unsw-1414">UNSW</a>
This article was originally published on <a href="http://theconversation.com" target="_blank">The Conversation</a>. Read the <a href="https://theconversation.com/future-ocean-cities-need-green-engineering-above-and-below-the-waterline-93843" target="_blank">original article</a>.
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jrobinson-rf4aSBido9

Green engineering needed above and below water in future 'ocean cities'

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<img src="https://counter.theconversation.edu.au/content/57114/count.gif" alt="The Conversation" width="1" height="1">
GUEST OBSERVER
In the 1953 short story The Man Who Planted Trees, a lone shepherd plants thousands of trees, transforming a desolate valley into a vibrant forest with pleasant villages and unspoiled wilderness. The moral of this story is a simple one: that perseverance and planting trees can make places more desirable to live.
Across the United States, the US Forest Service is proving this, neighbourhood by neighbourhood.
Within some neighbourhoods, scientists are documenting a connection between trees and a specific social improvement: a reduction in crime. These studies combine modern mapping technology with spatial and economic statistics to compare crime levels between similar urban neighbourhoods in the same city.
This research is becoming increasingly widespread and sophisticated. According to Kathleen Wolf, a research social scientist with the University of Washington and the US Forest Service, this is “part of a movement to understand the role of nature in public health”. Wolf observes:
"Now that we’re in the era of Big Data, we’re seeing an acceleration of crime-related research in a wide variety of disciplines and fields. We’re also incorporating data on things like disparities of green in urban communities."
Not only do healthy, well-maintained trees provide shade and benefit the ecosystem, they can have a social meaning: that people in that neighbourhood look out for each other.
<h2>Progress in Baltimore</h2>
One of the places we are conducting this type of research is Baltimore. One of the oldest cities in US, Baltimore has more than 600,000 residents. It is known for its rich historical heritage, a picturesque inner harbour, crab cakes … and for having some of the worst crime and poverty levels in the nation.
According to recent estimates, 25 percent of Baltimore residents and 37 percent of Baltimore children live in poverty.
Faced with one of the highest homicide rates in the country, the city implemented a youth curfew law in 2014 to keep unaccompanied children off the streets at night.
Baltimore also has an extensive team of urban research scientists, affiliated with both the US Forest Service Baltimore Field Station and the Baltimore Ecosystem Study, and a proactive non-profit organisation, The Parks &amp; People Foundation. These entities are working together to demonstrate a connection between adding trees and reducing crime in under-served neighbourhoods.
We worked in a research collaboration to look at the relationship between urban tree cover and rates of robbery, burglary, theft and shooting in under-served neighbourhoods in Baltimore. After controlling for income, population density, block-scale tree canopy and housing type, we found that a 10% increase in tree canopy corresponded to a roughly 12 percent decrease in crime.
According to Valerie Rupp, director of community greening for The Parks &amp; People Foundation in Baltimore, people are taking back their neighbourhoods. “While crime still exists, there’s been a shift to more minor, less violent crimes,” she says.
<h2>Pride and goodwill in Philadelphia</h2>
Less than 150 kilometres northwest of Baltimore is the city of Philadelphia, another historic metropolis. With a population of more than 1.5 million, Philadelphia also has its share of big-city problems.
Although Philadelphia’s homicide rate is lower than Baltimore’s, the city has one of the highest homicide rates of the country’s ten most populous cities.
The US Forest Service Philadelphia Field Station is working with city groups such as the Parks and Recreation Department and the Philadelphia Water Department to establish the “triple bottom line”, meaning improvements in three broad areas of impact – environmental, social and economic.
In terms of crime reduction, our studies have found that “green” stormwater infrastructure improvements resulted in significant reductions in narcotics possession and theft. According to Philadelphia police detective Hugh Davis, one can feel neighbourhoods changing and becoming safer over time. Davis says:
"It often starts out as a grant program to make landscape improvements, and then residents start to take ownership. It improves neighbourhood pride and goodwill toward the city."
<h2>Developing ‘green courage’ in the inner city</h2>
The theory behind urban greening and reduced crime levels is that when under-served neighbourhoods are made more pleasant, it can result in a healthier sense of community. In turn, it makes those neighbourhoods less hospitable to criminal activity.
In places like Baltimore and Philadelphia, city departments are working with communities to give people what some urban sociologists call “green courage”. This occurs when residents become more willing to work together after seeing improvements in their neighbourhood.
At the end of the day, urban greening is not simply about planting trees. It’s about people working together to make neighbourhoods better places to live.
We are working alongside these efforts, helping to document and provide a scientific basis for the work to spread and continue. For those of us who are working toward these goals, we sometimes wonder: are we planting trees to organise people or are we organising people to plant trees?
The best answer is probably “yes” to both.
J. Morgan Grove is research forester, United States Forest Service, and can be contacted <a href="https://theconversation.com/profiles/j-morgan-grove-281187" target="_blank">here</a>.
Michelle Kondo is research Social Scientist, United States Forest Service and can be contacted <a href="https://theconversation.com/profiles/michelle-kondo-281190" target="_blank">here</a>.
Both are authors for The Conversation.
The authors wish to acknowledge the contribution of Brian Cooke, an editor and writer for the US Forest Service Northern Research Station, to the writing of this article.
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