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Biodiversity: why architecture must get to the roots of the nature crisis

In this scan for RIBA Horizons 2034, Harriet Bulkeley highlights how the protection of life on Earth is crucial for mitigating the impact of global warming on ecosystems. Biodiversity is most often tackled in the context of natural landscapes. As rural species decline in the coming decade, the significance of urban habitats for nature must be realised.
  • today 19 July 2024
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Biodiversity is one of four scans that forms part of Environmental Challenge theme for RIBA Horizons 2034.

Graffiti of a tree on a building in La Rochelle, France, framed by real leaves (Photo: © Steprphotos |

As the crisis of the loss of biodiversity intensifies globally, cities are increasingly seen as important havens for nature.

This might seem counterintuitive. After all, the global urban population is set to reach four billion by 2030. Temperatures in cities are predicted to rise faster than anywhere else and urban expansion will potentially lead directly to the destruction of 290,000 km2 of natural habitat. [1]

Yet, as the dual crisis of nature and climate change unfolds, so too has the long-standing divide between town and country, nature and civility that permeated modernist thinking been replaced by a recognition of the increasingly hybrid and entangled forms that nature and urbanisation take. [2]

Cities are now at the forefront of concerns about what it means to live with and respond to the biodiversity crisis. The prominence of cities is in reports signposting the significance of urban habitats for nature as rural species decline. [3] It is in the second series of David Attenborough’s much-loved Planet Earth documentary that featured an episode on urban wildlife.

More importantly, cities’ prominence is in the Kunming–Montreal Global Biodiversity Framework. [4] This new plan agreed upon by national governments at the 'Nature COP' in December 2022 aims to conserve and restore nature while enabling society to benefit. The framework aims to “significantly increase the area and quality and connectivity of, access to and benefits from green and blue space” in urban areas.

By recognising cities’ critical role in responding to the biodiversity crisis, the framework opens up new opportunities, responsibilities and challenges for the profession over the next 10 years.

Cities – part of the problem or part of the solution?

The increasing prominence given to cities in the global response to the biodiversity crisis has primarily been driven by concerns over the threat that urban expansion poses to nature. [5]

The 2019 Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) Global Assessment Report demonstrated that we are losing nature at an unprecedented rate, with potentially up to a million species at risk of extinction. It identified the expansion of urban land use as one of the most significant drivers of biodiversity loss alongside land conservation for agriculture, climate change, invasive species and pollution. [6]

Less commonly recognised are the significant ways cities indirectly contribute to biodiversity loss. [7] For example, as key centres of consumption and production, urban areas –including suburbs – contribute significantly to the greenhouse gas emissions that lead to climate change. They are also important sources of plastic and nutrient pollution.

Additionally, built development in cities is driving the extraction of resources such as sand and aggregate used for concrete, destroying ecosystems worldwide. [8] The concentration of institutions, organisations and individuals that inhabit cities means that they are also vital in shaping societal values and fostering a growing disconnection with nature. The IPBES Global Assessment considers this one of the key root causes of the biodiversity crisis.

Yet this is far from a one-way relationship. There is growing evidence that nature matters for cities. Urban areas benefit from a range of what are termed ecosystem services. [9] These are how nature contributes to society by, for example, protecting coasts, cooling hot streets with shade, and slowing the flow of water to reduce flood damage – as well as providing opportunities for awe, wonder, spirituality, health and well-being.

The loss of nature and the benefits it provides for society is likely to undermine the resilience of urban communities, infrastructure and the built environment. Faced with these growing pressures, cities are now seeking solutions that allow them to work with and for nature.

Of course, the history of the modernist city is replete with examples of efforts to control nature towards urban ends. From large parks to waterways, urban planning and infrastructure development have served as a means through which nature has been brought into the city for particular ends. [10]

However, there has been a shift in thinking over the past few decades. The new perspective is that the urban arena is a means to address wider global sustainability challenges. While this approach to urban sustainability can be traced back at least to the Brundtland Report of the early 1980s, the focus on nature as playing a vital role in such solutions is more recent. [11]

An early iteration of the importance of harnessing nature towards urban sustainability can be found in the concept of ecosystem-based adaptation, introduced by the United Nations Framework Convention on Climate Change (UNFCCC) in 2008.

This approach includes conservation, restoration and the management of ecosystems intended to reduce climate impacts and increase societal resilience. Significantly, it was adopted by the World Bank as an alternative to mainstream adaptation measures based on technical solutions and grey infrastructure. [12]

Most recently, the more expansive concept of nature-based solutions (NBS) has been used as an umbrella term to capture a range of interventions that work with and for nature towards sustainability goals. Here, the emphasis is on the potential for such interventions to address multiple sustainability challenges simultaneously.

The European Commission, an early advocate and key stakeholder in this approach, suggests that NBS can “result in multiple co-benefits for health, the economy, society and the environment, and thus they can represent more efficient and cost-effective solutions than more traditional approaches” for sustainability. [13]

Towards nature-based solutions

As the importance of finding solutions to both the climate crisis and the loss of biodiversity has grown, NBS offer a glimmer of hope that it is possible to address the loss by working with nature, for nature. [14]

Globally, investment in nature-based carbon offsetting in the land and forestry sectors increased twenty-fold between 2016 and 2021 to reach a value of over 1.3 billion USD. [15] At the same time, the international climate and biodiversity COPs have been dominated by multiple examples of the possibilities that NBS present.

Even so, the financial investment and political capital being directed towards urban NBS remains relatively small, with estimates suggesting that just 0.3% of overall spending on urban infrastructure globally is being directed towards NBS. [16]

Within this arena, architects and built environment professionals have played a crucial role in showcasing the possibilities that cities hold. There have been several iconic projects, such as the Bosco Verticale in Milan [17], the Khoo Teck Puat Hospital in Yishun, Singapore, [18] the Rolls-Royce plant in the UK, [19] and One Sydney Park in Sydney, Australia. [20]

These are all examples where architects and designers have worked with NBS to enhance the quality of the built environment, using strategies that include green roofs, walls and structures, sustainable drainage and therapeutic gardens.

As well as producing attractive assets, these strategies also generate benefits such as improved thermal efficiency, flood protection, enhanced biodiversity and supporting the health and well-being of occupants.

Making just urban nature futures

Despite these important advances in how the sector is engaging with the challenges of urban sustainability and the opportunities that NBS provide, three critical challenges remain.

1. Rethinking models of risk and value

The first and most obvious challenge is that, across the built environment, NBS remain the exception rather than the rule. The iconic examples provided above – and often repeated in the popular industry press – are well known because of their rarity.

Structural conditions and institutional norms across the urban development sector create significant barriers to the uptake and mainstreaming of NBS. [21] For example, the rate of return on investment required, how risk is calculated, tacit knowledge and professional training have all been built upon concrete foundations – literally.

Bringing nature in – with its cyclical temporalities, uncertain futures, often unruly aesthetics and complexities that require alternative expertise – disrupts these stable ways of working. It requires new forms of calculating risk, value and futures.

As such, NBS are currently most often used only when they conform closely to existing models (for example, the use of simple green roofs as a form of insulation) or where existing approaches have reached their limit point – for example, where predictions of flooding frequency and magnitude mean that concrete solutions can neither fit nor be afforded within a particular scheme.

In this context, experimentation has become the norm and is a crucial means through which current ways of thinking and doing urban development are established. [22]

But making progress will require architects not only to adopt the new but also to question the old. In the context of the twin crises of climate and nature, architects need to confront current standard ways of assessing risk, investment and value if the kinds of experimentation seen currently with NBS are to gain more traction. [23]

2. Designing for system integration

The second challenge is that, as things stand, there is a danger that how the architecture and built environment professions are engaging with NBS amounts to little more than a green gloss that conceals the significant ways that urbanisation contributes to the biodiversity crises.

The practice of incorporating NBS one building or one masterplanned development at a time, albeit set within its immediate context, tends to isolate fragments of urban development from their wider potential impact. As the IPBES Global Assessment has shown, land use conversion through urbanisation is a significant threat to biodiversity.

And while this may be obvious at the urban fringe, within cities it is much less so. Areas that appear as scraps of unwanted space, brownfields or wastelands can be important areas for biodiversity not only in themselves but as part of the patchwork of loosely interconnected spaces across cities that provide for nature. [24]

Creating meaningful NBS will involve moving built environment professionals’ – including architects’ – perspective beyond the direct envelope of singular developments to consider how different sites and interventions can contribute to a multiplicity of urban sustainability goals because of how they interweave with existing spaces, flows and connections. [25]

At the same time, efforts to generate NBS must not be undertaken in isolation from the contribution that urban development might make to the root causes of biodiversity decline globally. [26]

While the material footprint of the built environment is increasingly under scrutiny for its contribution to climate change, its biodiversity impact also needs to be considered. The profession must scrutinise the biodiversity impact of supply chains for critical materials such as sand, concrete, steel and wood much more closely.

Likewise, there are significant opportunities to build more circular economies around the development of NBS by attending to how, where and by whom the very stuff of nature being incorporated is itself created.

For example, in Hyderabad, India, [27] the city’s programme to radically increase the extent of the tree canopy has been supported by the development of urban plant nurseries. In the Netherlands, UK and Ireland, More Trees Now [28] works with local volunteers to find unwanted tree saplings and make them available for planting.

To progress NBS that are truly sustainable, architects and built environment professionals will need to enter into new system-wide partnerships to sustain ambitions to bring nature into urban development.

3. Planning for fairness and justice

The third, and perhaps most critical, challenge concerns the (unintended) consequences that urban NBS can have for social and environmental justice.

Access to urban nature and its benefits is already highly uneven within and between cities. [29] There is now also growing evidence that interventions designed to address urban sustainability challenges, such as climate change and biodiversity – including those that work specifically with NBS – can sustain and exacerbate these inequalities by contributing to green gentrification. [30]

Introducing nature into an urban area inflates its land values and property prices, with the result that its pre-existing communities may be displaced and those on low incomes are effectively excluded.

Similarly, when NBS are designed with dominant Western tropes of what ‘good’ nature entails, the benefits and values that diverse groups hold for nature, including those of indigenous peoples and local communities or black and minority ethnic groups, can be excluded.

The provision of urban NBS is not just about realising multiple benefits but also ensuring that the process is inclusive and just. [26] This requires careful consideration of who is involved and at which stage in the design process.

Too often, nature is an afterthought to the main business of urban development. Giving it due consideration requires that decisions about how and why to incorporate NBS, and for whom, must be made much earlier in building and urban design practice.

Likewise, processes of gentrification and exclusion are exacerbated when the goal of incorporating nature is to increase profit through land sales and to create privatised benefits for owners and residents.

No matter how high the walls that enclose it, nature is always at least in part a public good – cooling the city, retaining water, harbouring biodiversity and so forth.

The critical challenge for architects and built environment professionals here is how to work with more fluid boundaries between the public and private realms. Doing so will make it more likely that developments benefit the investor and, at the same time, help to fully realise the contributions that nature can make to urban communities.

Urban nature, transformed?

As the world approaches the second anniversary of the 2022 Montreal-Kunming Global Biodiversity Agreement – with a new round of talks to be held in Cali, Colombia in November 2024 – all eyes are turning to whether it is now possible to move from agreement to action on and for nature.

Yet it is clear that simply more of the same kind of action will not be good enough.

For architects, taking the crisis of nature seriously requires a fundamental rethinking of how we live alongside and with nature every day. From our back gardens and balconies to the scraps of wasteland and the edges of urban sprawl, the first and crucial step is to let nature in.

Moving towards transformative change for cities and nature will also require built environment professionals to reconceive what constitutes value, where the boundaries of their responsibilities lie, and what it means to create a flourishing city for all.

As humankind faces the environmental challenges ahead, transforming cities with and for nature might just be one of its last and best hopes.

Author biography

Harriet Bulkeley FBA is a Professor in the Department of Geography, at Durham University and the Copernicus Institute of Sustainable Development, at Utrecht University.

Her research focuses on environmental governance and the politics of climate change, energy, nature and sustainable cities. She currently convenes the Horizon Europe NATURESCAPES project (2023 to 2027). She has undertaken commissioned research for the UK government, European Commission, NGOs, UN-Habitat, the OECD and the World Bank.

In 2023, Harriet was appointed to the Scientific Council of the European Research Council and as an international honorary fellow of the American Academy of Arts and Sciences.

Portrait, courtesy Harriet Bulkeley

RIBA Horizons 2034 sponsored by Autodesk

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