AND INFRASTRUCTURE TRANSITION
Summary of the Transition
Deploying ‘green infrastructure’ 1 and making space for nature within built landscapes to improve the health and quality of life for citizens and to reduce the environmental footprint of cities and infrastructure. This transition recognizes the dependency of urban communities on well-functioning ecosystems to sustain the human population, the majority of which is living in cities, the teleconnections between cities and nearby and distant ecosystems, and the importance of spatial planning to reduce the negative impacts on biodiversity of urban expansion, roads and other infrastructure.
Rationale and benefits
While the rate of population growth is slower than at any time since 1950, world population is expected to grow to around 8.5 billion by 2030 and 9.7 billion by 2050,2 with the proportion residing in urban areas increasing from 55% in 2018 to 68%
by 2050.3 While almost half of the people living in urban environments live in towns or cities with fewer than 500,000 people, there are currently 33 cities with more than 10 million inhabitants (megacities). By 2030 the number of megacities is expected to reach 43, with most of these being in developing regions.4 Growing urban populations and the associated need for infrastructure will place increasing demands on resources, and constitute an important driver of land-use change. The status of biodiversity, and the prospects for reaching the 2030 Agenda for Sustainable Development more generally, will depend in large part on how these demands are managed.5 Moreover, the increasing trend towards urbanization risks separating people further from nature, with potential negative effects on human health and reduced understanding of biodiversity, the ecosystem services it provides and their importance.
Sustainable management of cities and urban-ization can help to reduce the impacts of growing population on biodiversity, while also helping to contribute to other societal challenges including human health (see One Health transition). Green
spaces in urban areas can help to improve mental health.6 Access to green spaces also increases oppor-tunities for physical activity which may reduce the risk of several noncommunicable diseases, as well as improved immune function.7 The critical impor-tance of urban nature in providing resilience in time of crisis has been demonstrated by the COVID-19 pandemic, during which access to green spaces has been an important factor in supporting health and well-being while people observe social distancing requirements.8
‘Nature-based solutions’ to climate change mitigation and adaptation are especially valuable in cities where they can address multiple urban challenges simultaneously, including flooding, heat stress, drought and pollution of air and water, as well as reconnecting people with nature (see Sustainable Climate Action transition).9 Maintaining and encouraging food production within urban and peri-urban areas can both improve the resilience of urban populations, and benefit biodiversity by reducing the pressure for further conversion of distant ecosystems to cropland to feed growing urban populations (see Food and Land and Forests transitions).10
The rapid development of infrastructure beyond cities, especially roads, represents a substantial impediment to meeting goals for biodiversity in the coming decades. The number and extent of roads is forecast to expand dramatically with 25 million kilometres of new roads anticipated by
The sustainable Cities and Infrastructure transition
The sustainable Cities and Infrastructure transition 169 2050, a 60% increase in the total length of roads
since 2010. Around 90% of all road construction is expected to occur in developing countries, including in many of the last wilderness areas such as those in the Amazon, New Guinea, Siberia and the Congo Basin.11 New roads create multiple threats in high biodiversity areas, including fragmen-tation of habitat, opportunity for land colonization, and the conditions for increased hunting and other forms of over-exploitation, as well as intro-duction of invasive alien species. Among many other impacts, the world’s remaining populations of apes in equatorial Africa and Asia are especially vulnerable to the expansion in roads and other infrastructure including railways, hydroelectric dams, power lines, gas lines and mining.12 A major global driver of infrastructure development across Asia, Europe and Africa, China’s $6 trillion Belt and Road Initiative, presents many risks for biodiversity and new cooperative modes of governance will be needed to mitigate these. However, currently there are few safeguards for biodiversity in the lending requirements applied by the institutions providing finance for the initiative.13 Widespread application of additional measures to minimize the impacts
to biodiversity from infrastructure development will therefore be among the transitions required to achieve the 2050 Vision for Biodiversity.
Key components of the transition
promote locAl-level urbAn governAnce And trAnsdisciplinAry plAnning, accounting for biodiversity among other societal needs when decisions are made on urban development, preventing urban expansion from compromising ecosystems both within and outside cities on which people and biodiversity depend, including forests, watersheds and flood plains.
mAke greAter use of green infrAstructure, such as preservation and creation of green spaces and wetlands, to support multiple needs of urban populations as well as to promote urban biodiversity.
tAke Account of the footprint of cities on ecosystems in distAnt locAtions through encouraging healthier diets, more sustainable use of materials in construction and minimizing energy use.
Haugenzhays Zhang / Unsplash
reflect biodiversity considerAtions in the plAnning And development of infrA-structure investments, such as the design and management of transportation systems, and other linear infrastructure, through processes such as biodiversity-inclusive environmental assess-ments and large-scale zoning to avoid the most vulnerable areas for biodiversity, and application of measures to preserve ecological connectivity, for example through overpasses, underpasses and green infrastructure.
Progress towards the transition
Numerous networks and initiatives have emerged in recent years to promote a transition towards more sustainable models of urbanization. At a global level, the United Nations Conference on Housing and Sustainable Urban Development adopted the New Urban Agenda in 2016, subsequently endorsed by the UN General Assembly. The agenda envisions, among other things, cities and human settlements that ‘protect, conserve, restore and promote their ecosystems, water, natural habitats and biodi-versity, minimize their environmental impact and change to sustainable consumption and production patterns’.14 While overall application of this agenda in urban planning has been limited, examples of initiatives supporting its principles include: a programme in Australia aiming to plant 20 million trees to establish green corridors and urban forests to re-establish native vegetation, provide native habitat for threatened species, sequester carbon and improve the liveability of cities and towns;15 efforts in the Republic of Korea to build a green network through developing urban forests including
‘meditation forests’, school forests and tree-lined streets;16 inclusion of urban biodiversity as a new thematic focus in the Philippines national biodi-versity strategy, recognizing that 65% of the country’s population is expected to live in cities by
2050;17 and the designation of special green conser-vation areas under Japan’s Urban Green Space Conservation Act, promoting the conservation, restoration, creation and management of green spaces.18
Some linkages with other transitions
lAnd And forests: depends on services from protected or restored ecosystems, essential to urban populations; contributes to reducing land pressure on ecosystems through improved planning of urban expansion and infra-structure development
food: contributes to more sustainable food supply chains and reduced food waste, through a new urbanization agenda that also includes innovations such as urban gardens and city farms
freshwAter: depends on sustainable management of freshwater ecosystems for urban water supply and quality;
contributes to the conservation and restoration of freshwater ecosystems through reduced water consumption, controlled urban expansion and use of green infrastructure
climAte Action: contributes to climate mitigation through use of green infra-structure, and to climate adaptation by increasing resilience among urban populations.
one heAlth: contributes to mental and physical health through greater access to urban green spaces, and by reducing pollution
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