Global Climate action and sustainable development

Cities must play an important role in halting biodiversity loss


The planet’s life support system is in danger. Biodiversity is declining across the world and with the UN Biodiversity Conference of the Parties (otherwise known as COP15) beginning this week, world leaders are under pressure to tackle this urgent issue. In this blog, Alice Creasy & Ben O’Hickey from WSP’s Net Zero Cities and Natural Capital teams reflect on the role that cities must play in tackling the biodiversity crisis.

The word ‘biodiversity’ is probably more likely to conjure up images of lush rainforests and rich wetlands than a busy city, but the planet’s urban centres are important habitats for a huge diversity of fungi, flora and fauna. Whether it’s through official conservation projects or out of pure necessity, plants and animals have always found ways to co-exist with us in cities.

With biodiversity in crisis across the planet, it is increasingly important to understand our relationship with the natural world and explore the ways in which cities can support the development of diverse local ecosystems.

Drawing on case studies this article will explore the importance of urban biodiversity and the role cities can play in halting its decline.

Biodiversity is the term for the variety of ecosystems, species, and genes in one habitat and across the natural world. From the air we breathe and the water we drink to medicines and food systems this complex network of local and global ecosystems underpins life on earth.

In addition to the planetary life-support systems provided by biodiversity, ecosystems support vital economic and social services. More than half of global GDP – $42tn (£32tn) – depends on high-functioning biodiversity. In cities, diverse ecosystems help to build resilience to climate change, sequester carbon and improve health and wellbeing.

Despite the vital role that biodiversity plays in supporting life on this planet, the world is failing to meet its biodiversity targets. Global wildlife populations have declined by 69% since 1970 and without drastic action, roughly one in four species are at risk of becoming extinct.

With a fifth of countries facing ecosystem collapse the expansion of cities across the world is likely to lead to the loss of 290,000 km2 of natural habitat between 2000 and 2030. By 2100 it is projected that urban expansion will lead to between 11 and 33 million hectares of natural habitat loss, with 16% of planned urban expansion impacting Key Biodiversity Areas.

Not only will the physical expansion of cities have an impact on local ecosystems, but the footprint of urban production and consumption will have a global impact. From pollution and raw materials for construction, to pressure on global food and water systems, growing cities are having a serious impact on local and global biodiversity.

As cities expand, research has found that access to neighbourhood greenspace is declining, leading to a drop in local biodiversity and vital ecosystem services. In England and Wales for example housing developments built between 2009-2021 have up to 40% less local green space compared to areas where homes are mainly late 19th- and early 20th-century. Furthermore, after a decade of budget cuts, many existing greenspaces have fallen into disrepair or been sold off by local authorities. Funding for local green spaces in England has fallen by £330m a year since 2010.

This loss of green space is leading to what is called ‘shifting baseline syndrome’ which refers to a pattern whereby people of each generation perceive the state of the ecosystems they encountered in their childhood as normal and natural. So, when wildlife is depleted, while we might notice the loss, the baseline by which we judge the decline does not take into account its full scale.

As the 15th COP meets to discuss the global biodiversity crisis in Montreal, a city whose mayor has announced plans to make it the “greenest city in North America”, what can be done to save our urban biodiversity?

There is an abundance of success stories from around the world that can be used to inspire actions that will support urban biodiversity. These range from incorporating valuable habitats within multi-purpose infrastructures (such as sustainable urban drainage systems) to retrofitting new habitats with green walls or designing complete “Nature-based solutions” (e.g. the Copenhagen Courtyard for the Future). Where green space already exists, techniques are becoming commonplace to create high-value habitats, such as Miyawaki forests or diverse urban wildflower meadows.

These examples all represent actions trying to provide more valuable habitats for biodiversity by making the most of the available space, unfortunately, this approach is unlikely to create more than small, fragmented areas of habitat isolated within the much larger urban matrix. To truly encourage biodiversity, return and recovery in our urban spaces space needs to be given back to biodiversity.

The development of the Natural Capital economy and green finance provides one opportunity to meet this challenge. The development of new financial models such as the Greater Manchester Environment Fund provides a way to channel more funding and investment into the natural environment. This focus on green recovery has resulted in success for Manchester with the recent opening of the first city centre park in over 100 years, on previously brownfield land this year.

Within England, new legislative drivers such as the Environment Act 2021 and the proposed requirement for Biodiversity Net Gain within it is likely to result in further funding and opportunity for greenspace creation. The difficulty in providing on-site biodiversity net gain in combination with the requirements for delivering offsets within the same local authority will likely cause a demand in habitat offsetting within metropolitan districts. If managed correctly within Nature Recovery strategies this could be the support that urban biodiversity needs.

As the climate and biodiversity crisis deepens with every passing year, going forward the planet’s urban centres must play an important role in halting biodiversity decline both within and out with municipal boundaries. A traditional imagining of the urban-rural binary has left us with an image of cities as environments that are devoid of nature, but this is simply not true. The cities highlighted in this article provide an example of what could be achieved if urban biodiversity recovery is put at the heart of planning over the coming years.


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