Cultivating biodiversity for resilient urban futures

Shockingly, over 80% of the urban population is exposed to air pollution exceeding World Health Organization standards, with particulate matter pollution ranking as a significant cause of mortality.

Yet, the impact doesn't stop at compromised air quality—urbanisation also amplifies the Urban Heat Island (UHI) effect. This phenomenon, characterised by elevated temperatures in urban areas compared to their rural counterparts, is exacerbated by materials with low albedo, high volumetric heat capacity of concrete and asphalt, urban morphology, and heat generated from anthropogenic sources.

Furthermore, emissions of sulphur dioxide and nitrogen oxides contribute to "acid rain," negatively affecting water bodies, vegetation, and soil. This acidification impairs ecosystems' ability to provide crucial services such as nutrient cycling, carbon sequestration, and water provision. The quality of drinking water is jeopardised, and air pollution negatively impacts vegetation that naturally filters water systems. As vegetation suffers, so does its role in capturing carbon, further exacerbating the climate crisis impacts.

In the face of this daunting scenario, urban biodiversity emerges as a beacon of hope. It encompasses the vast array of life forms within city limits, from micro-organisms in the soil to towering trees in parks. Despite the prevailing perception of cities as grey concrete jungles, they possess the potential to be vibrant hubs for biodiversity if deliberate efforts are made to coexist with nature.

Strategic placements of trees in urban areas can cool the air by 2-8 degree centigrade. Large urban trees function as filters for urban pollutants and fine particulate matter, and reduce noise pollution. Preserving urban biodiversity isn't just an environmental imperative; it yields economic benefits as well. Green spaces enhance property values, making cities more attractive places to live and work. Additionally, urban biodiversity can stimulate tourism and create employment opportunities related to parks maintenance, wildlife conservation, and eco-tourism.

Recognising the critical role of urban biodiversity, the "Kunming-Montreal Global Biodiversity Framework" outlines ambitious goals for 2030. It emphasises the need to increase the area, quality, and connectivity of green and blue spaces in urban areas sustainably.

In the face of unprecedented urban expansion, the imperative to transform our cities into vibrant, green havens has never been more crucial. As we forge ahead into an era of increasing urbanisation, the need to balance growth with environmental preservation becomes paramount. Here are six interconnected strategies to seamlessly integrate urban development with the conservation of biodiversity:

• Urban planning should embrace a paradigm shift, elevating green spaces to the forefront. Parks, green roofs, and community gardens must be integral elements of city design. However, careful consideration is warranted in urban gardening to mitigate potential health hazards. Pollen from plants can trigger asthma and allergies. Striking a balance between male and female plants reduces airborne pollen, creating a healthier urban environment. Additionally, the incorporation of native plants fosters a symbiotic relationship with local animals, promoting biodiversity.
• Preserving and restoring urban wetlands, forests, and waterways is indispensable for maintaining ecological balance. Recognising the multifaceted role of urban wetlands in flood control, water purification, and as vital habitats for migratory birds, steps should be taken to safeguard these critical ecosystems.
• The visual allure of greenery is just one facet of its significance. Plants play a pivotal role in ameliorating the adverse effects of poor air quality. Trees and plants filter contaminants through their leaves, dispersing cleaner air over wide areas. However, a nuanced approach is required, considering that trees also release volatile organic compounds (VOCs) that can exacerbate pollution. Strategic placement of hedges and living walls in densely populated areas can contribute to cleaner air. Moreover, the preservation and enhancement of biodiversity, encompassing plants, insects, and animals, should be central to pollution reduction efforts.
• Communities are the backbone of sustainable urban development. Engaging local residents through awareness generation and in the planning, joint articulation of goals and upkeep of green spaces is essential. Initiatives such as community gardens, tree planting drives, and citizen science projects empower residents to actively contribute to biodiversity conservation. Additionally, integrating nature in education programmes through ‘Forest Kindergarten’ creates an emotional link to nature from a young age where children spend most of their time outdoors and are encouraged to discover, learn and play with what can be found in nature.
• Local governments play a crucial role in reducing citizens' biodiversity footprint by endorsing initiatives that offer alternatives to traditional consumption. This includes supporting urban gardening projects and circular economy practices like repair cafés and second-hand markets. To incentivise sustainable consumption, regulatory powers can be employed. Notable examples include Indian states such as Mexico City's plastic bag ban since January 1, 2020, and 1204 French municipalities pledging to avoid pesticides in managing green areas. These measures collectively contribute to a more sustainable and biodiverse future.
• While every city faces a unique set of challenges and opportunities, it is possible to identify groups of peer cities—those sharing certain commonalities and potential policy solutions that relate to the biological, geological, social, and governance context—by means of a simple typology. This typology can help highlight policy choices related to the allocation of urban green and blue space, or other actions related to promoting urban biodiversity and ecosystem services. Its components reflect information including city age, size, and population density; economic profile; equity in allocation of resources; baseline levels of biodiversity; and amounts of green and blue space. Cities may relate to one another in some or all of these metrics and can possibly leverage the South-South and Triangular Cooperation mechanism for knowledge and technology transfer.

As our cities evolve, the call for nurturing urban biodiversity becomes more urgent than ever. It's not just a matter of aesthetics; it's a necessity for our health, economy, and the very fabric of our existence. Green cities are not a luxury; they are a prerequisite for the well-being of current and future generations. It's time to transition from grey to green and embrace a sustainable, biodiverse urban future—one where the concrete jungle thrives in harmony with the rich tapestry of life that makes our planet extraordinary.

This article is authored by Kaustuv Chakrabarti, independent researcher, value chains, agri-food systems and SSTC.