Rewilding our cities could reduce the impact of extreme weather

Sustainable Leaders | Europe

By Hannah Corsini, Freelance Writer

Published November 16th, 2022

The Zoological Society of London (ZSL) have released a report outlining the potential benefits of rewilding urban cities, including benefits to the economy and wildlife recovery, along with the potential reduction of pollution and mitigation of harm caused by extreme weather events.

Rewilding proposes one of the solutions to the dual issues of biodiversity loss and climate change. Typically, rewilding aims to mitigate the impact of human intervention on natural areas, and in doing so restore self-managing ecosystems without further input. This creates a kind of hands-off environmental management, in comparison to traditional methods of conservation, which focus on sustained human intervention.

Yellowstone National Park, where wolves have been reintroduced and have had positive effects on the park’s ecosystem. Reintroducing apex predators causes a trophic cascadeーa ripple effect through the food chainーby decreasing the number of herbivores feeding on the native plant species. | Paul F. Lindberg/ Wikimedia commons

Rewilding has generally been associated with rural areas. However, given that 68% of the human population is projected to live in urban areas by 2050, their inclusion in environmental initiatives is becoming increasingly important. Rewilding could, therefore, offer a chance to restore some of their ecological processes and interactions whilst boosting their resilience to climate change. Although it is unlikely that we will ever restore these spaces to the state of their native ecosystems, rewilding could help to ‘future-proof’ cities and towns.

‘Rewilding aims to mitigate the impact of human intervention on natural areas.’

In the report, the ZSL describes rewilding as a call ‘for strong connections with wildlife to be rebuilt,’ and suggests that, concurrent with mitigating extreme climate events and biodiversity loss, rewilding could also reduce the risk of zoonotic disease spread to humans..

What could urban rewilding look like?

One initial way in which cities could practice rewilding, would be the near-elimination of human procedures such as mowing lawns, watering and weeding. These activities suppress vegetation, creating ‘monocultures and manicured green spaces’ーareas of land which have been dominated by humans to the extent that they have become artificial representations of nature. Approximately 24% of the Greater London Area consists of private gardens, but only 57% of this area is occupied by vegetation, a percentage which is currently declining.

Hyde Park, London. Green spaces in London are diminishing in quantity, making the existing parks all the more important. | Igor Wang / Unsplash

This practice could extend to public areas as well as private parks, playgrounds, even cemeteries. Places of faith are often quiet and undisturbedーpresenting an ample opportunity to rewild their outdoor areas.

Disused railway tracks and railside verges are also examples of areas where intensive management could be stopped in order to allow rewilding. Network Rail recently made commitments to enhancing the biodiversity throughout its holdings, rethinking its approach to lineside management by allowing vegetation and fauna to flourish, instead of calling for its removal.

‘ZSL describes rewilding as a call for strong connections with wildlife to be rebuilt.’

Countless more transformations in the way in which landowners manage their properties are required in order to achieve rewilding on a larger scale. In 2005, the ZSL changed its management regime of London Zoo by putting an end to mowing around the car park, choosing solely to remove thistles and docks, cutting around the edges and tracing a pathway through the middle of the park. Coupling this with rotational management such as coppicing has meant that the car park has seen a surge in wildlife such as hedgehogs and butterflies. If a majority of urban landowners implemented similar practices, we could see effects such as these reshape the nature of urban areas across the UK.

Urban wetlands can also serve as target areas for rewilding. In many cities, urban rivers are severely polluted. Large sections of rivers are also often disconnected from their river-banks, meaning that the river-bank gets no access to the river’s nutrients, adversely affecting the biodiversity of this area.

Wetlands are often drained away, and the land converted for developmental purposes, putting the flora and fauna which depend on them at risk. But the damage can be undoneーwaterways can be re-naturalised and habitats created for freshwater species.

Reconnection to floodplains, as carried out by the Active, Beautiful and Clean (ABC) waters programme to Singapore’s rivers, for example, allows water to drain away naturally rather than requiring extensive drainage systems.

Beavers, a keystone species which have been reintroduced to the UK as part of rewilding projects. | Steve / Wikimedia commons

In some urban areas, keystone species such as beavers and water voles could also be reintroduced, as they often perform important ecological processes. Starting from 2015, beaversーhunted to extinction in the UK centuries agoーhave been gradually reintroduced into certain areas of the UK, a move which has bolstered local ecosystems. Their ability to build dams using their remarkably tough teeth means that they facilitate the accumulation of pools of water, in which wildlife such as amphibians, insects and fish can thrive.

Making cities resilient to climate change

In order to limit the average global surface warming below 1.5 ℃, it is no longer sufficient to stop pumping carbon into the atmosphere, we need to remove it too. Urban planning needs to start accounting for the potential of these events in order to minimise their aftermath.

Allowing native vegetation to flourish has the potential to both reduce carbon emissions and boost carbon sequestration capacity. Natural ecosystems like trees, peatlands and salt-marshes are specifically adapted to capturing carbon dioxide and storing it, so rewilding could help to mitigate some of the effects of climate change.

‘Allowing native vegetation to flourish has the potential to both reduce carbon emissions and boost carbon sequestration capacity.’

Increased vegetation cover, coupled with the ‘greening’ of infrastructure such as roofs and gardens, can help cool cities during heat-waves. With people already dying from heat-related illnesses in urban ‘heat islands,’ there is a demand for cooling technologyーwhich tends to demand extensive energy consumption, resulting in the burning of yet more fossil fuels. Rewilding is a simpler, less environmentally-costly solution where greenery provides shade to buildings and takes up heat energy through the process of evapotranspiration.

Rewilding cities has the potential to reduce floods. | Dibakar Roy / Unsplash

On the opposite end of the spectrum, rewilding also has the potential to reduce risk of flooding. In areas of land with trees and scrubs, water is more easily able to penetrate the soil, allowing it to be soaked up like a sponge.

It is estimated that reforesting just 5% of uplandーareas where the land is high-up or hillyーcould reduce flood peaks by 29%. Restoring wetlands is yet another way to reduce flood risk by enabling a slower, more natural water flow that protects downstream settlements from flooding.

Increasing wildlife biodiversity and connectivity

Urban rewilding could have the ability to increase habitat connectivityーan increasingly important focus in wildlife restoration. Human degradation has resulted in ‘patches’ of habitats: small areas in which certain species can thrive, but which are isolated from other habitats. Increasing connection between habitat patches has been theorised to improve gene flow and make small populations less vulnerable to localised extinction events.

This is important given the number of species which rely on urban areas to support them. Take, for example, the West European hedgehog, which has reduced in numbers in the UK from 1.5 million in 1995 to under 1 million in 2015, but continues to persist in cities and towns. As urban land increasingly encroaches on rural land, it is important to maintain the diversity of habitats which support our world’s wildlife.

‘Increasing connection between habitat patches has been theorised to improve gene flow and make small populations less vulnerable.’

Increased ecological diversity in urban areas also has the potential to restore natural pathogens and predators, which are able to eliminate pests and therefore reduce the need for chemical interventions, which are often costly to the planet. Allowing ecosystems to self-regulate could remove a lot of the time and money humans typically spend on managing ecosystems in these ways.

The West European hedgehog, a species highly dependent on urban areas for its continued survival. | Alexas_Fotos / Unsplash

The human well-being connection

As well as the potential to reduce air pollution, urban rewilding has the capacity to reduce the impacts of heat-waves on human health through the cooling effect provided by increased vegetation cover.

Availability of green spaces has also been associated with lowered mortality rates, along with improved mental health and emotional connection to nature. Disorders like depression, diabetes and weakened immunity have all previously been linked to deficits in nature, reflecting the increasing disconnect between humans and our environment.

‘Urban rewilding has the capacity to reduce the impacts of heat-waves on human health through the cooling effect.’

The coronavirus pandemic highlighted both the need for green spaces and the inequality of access to them. For example, a 2020 report by the National Trust found that in Britain, black and Asian people are able to visit green spaces 60% less often than white people, and that there are additional socioeconomic barriers to engaging with nature, such as owning a car. Rewilding urban areas could help to alleviate the gap between such groups.

Rewilding is also important when we think about communicable diseasesーparticularly those of a zoonotic nature, i.e. transmitted from animals to humans. Human developments often encroach on wildlife habitats, juxtaposing our immune systems with theirs.

Animals that remain in their natural habitats have been shown to have stronger immune systems, and the integration of human, animal and environmental health has been referred to as a ‘One Health’ conceptーthe idea that deteriorating animal and environmental health has severe influences on human health, perhaps best exemplified by the ongoing COVID-19 pandemic.

A grey squirrel sits on the fence of a London park. Grey squirrels are considered to be an invasive species. | Alexandru Vicol / Unsplash

The risks of urban rewilding

It would be untrue to state that there are no risks posed by urban rewilding. Criticisms of rewilding tend to revolve around its uncertainties as it is hard to predict everything that could result from a rewilding project.

One such unpredictability is the potential emergence of invasive species; species which spread across an area, dominating over the native species and causing harm to environmental health and sometimes to human health and the economy. An example of an invasive species is Japanese knotweed, which was initially introduced to the UK in the 1850s and has since proliferated across the British Isles.

In areas colonised by Japanese knotweed, nutrient cycles are altered and plant diversity is lowered. By leaving areas alone with little human management, it is possible that exactly the right conditions could be fostered for invasive species like Japanese knotweed to take over.

‘One such unpredictability is the potential emergence of invasive species.’

Another factor to consider is the fear that animals will take priority over particular classes of humans. ‘Green gentrification’ refers to a process of exclusion and displacement of disenfranchised humans as a consequence of environmental projects, often due to poorer residents being priced out as areas become more inhabitable and pleasant to live in.

A historical example of this is the establishment of Yellowstone National Park, where indigenous communities were forced out of the land, and a military post established in 1879 to violently prevent them from re-entering. Along with modern green gentrification, this shows how marginalised voices have been silenced in the name of protecting nature.

If urban rewilding projects want to garner public support, it is important that they consider the voices of urban residents, and consider that ‘nature’ as a term does not necessarily exclude humansーin fact, the very point of rewilding is often asserted to re-found a connection between the two.

David Johns writes in the collection of essays Rewilding that the distinction between wild and tame arose in societies determined to create a binary around what was ‘domestic, safe, predictable, human.’ Perhaps, in allowing rewilding to occur in such urban areas, we will discover that the binary between what is human and what is wild is not so rigid after all.

Featured image: Ben Garratt | Unsplash

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