The City Biodiversity Index: Measuring Urban Biodiversity for Sustainable Planning

Cities cover only a small fraction of the planet’s land surface, yet they shape ecological outcomes far beyond their boundaries. As urban populations swell and concrete replaces canopy, a pressing question emerges: how do we measure whether a city is hostile or hospitable to the living world around it? The City Biodiversity Index, better known as the Singapore Index on Cities’ Biodiversity, was created to answer exactly this question. It gives urban planners, ecologists, and local governments a structured way to evaluate how well a city protects nature, and how that performance changes over time.

The origin story of the Singapore Index 🔗

The idea for a dedicated urban biodiversity tool took shape in May 2008, when Singapore’s then Minister for National Development, Mah Bow Tan, proposed the concept at the Ninth Conference of the Parties (COP-9) to the Convention on Biological Diversity in Bonn, Germany. The motivation was straightforward. Existing tools like the Environmental Sustainability Index and the Environmental Performance Index were designed for countries, not cities, leaving a gap for urban-scale assessment.

Singapore’s National Parks Board (NParks) led the technical work, partnering with the CBD Secretariat and a taskforce of international experts. Between 2009 and 2011, three expert workshops shaped the framework, and over thirty cities tested early versions of the index in pilot studies. After several rounds of refinement, the tool was formally adopted at COP-10 in Nagoya, Japan, in October 2010, and named the Singapore Index in recognition of the country’s leadership.

A decade of real-world use revealed where the original framework could be sharpened. In September 2021, after extensive consultation with IUCN members, UN agencies, and local governments, a revised version of the index was launched. The update broadened the scope of ecosystem services covered and used modern tools like satellite imagery and spatial analysis software to make evaluation more accurate and accessible.

How the index is structured 🔗

The Singapore Index has two parts. The first is the Profile of the City, which gathers background information such as physical and geographical features, climate, population, administrative boundaries, and economic context. This profile is essential because biodiversity in a coastal city like Mumbai cannot be compared directly to a high-altitude city like Shimla. The profile situates the score in context.

The second part is the scoring framework itself, built around 23 indicators grouped into three core components: native biodiversity, ecosystem services provided by biodiversity, and governance and management of biodiversity. Each indicator is scored on a scale of zero to four, producing a maximum possible score of 92 points across all indicators. Crucially, cities are not ranked against each other. Each city measures itself against its own baseline, allowing comparison over time rather than competition between very different urban contexts.

Component one: native biodiversity in the city 🔗

Ten of the 23 indicators sit under native biodiversity, making it the largest component. These indicators look at the proportion of natural and semi-natural areas, the diversity of ecosystems, habitat fragmentation, and the presence of five categories of native species. Three species categories are fixed across all cities: plants, birds, and butterflies. The remaining two are chosen by each city based on what is locally relevant, which could be amphibians, reptiles, mammals, freshwater fish, or other groups.

This component also captures the area of natural habitats restored, the existence of invasive species, and the proportion of protected natural areas. Together, these indicators paint a picture of biological wealth and whether the city is gaining or losing it.

Component two: ecosystem services provided by biodiversity 🔗

This component recognises that urban nature is not just decorative. Forests, wetlands, and green corridors actively regulate water, store carbon, cool the air, and provide spaces for recreation and learning. The original index had four indicators here, covering the regulation of water quantity, climate regulation through carbon storage and the cooling effect of vegetation, the area of parks with natural areas, and the number of formal education visits per child to such parks.

The 2021 revision expanded this section to better reflect the wide range of services biodiversity offers, from pollination to flood control to mental health benefits. Cities like Bengaluru, where lake encroachment has reduced groundwater recharge and worsened urban flooding, illustrate exactly why these services need to be measured rather than assumed.

Component three: governance and management of biodiversity 🔗

The remaining indicators evaluate how seriously a city institutionalises biodiversity work. This includes the existence of a local biodiversity strategy and action plan, the budget allocated to conservation, the number of biodiversity projects, the level of inter-agency coordination, the involvement of partnerships with NGOs and academia, and the extent of public outreach and education. Governance often determines whether ecological wins are sustained or quietly lost between political cycles.

Why the self-assessment design matters 🔗

One of the most thoughtful design choices in the Singapore Index is that it is a self-assessment tool for cities to evaluate their progress against their own individual baselines. There is no league table where Singapore competes with Curitiba or Edmonton. This avoids the trap of comparing cities with vastly different climates, sizes, and histories, and instead encourages each city to focus on its own trajectory.

The recommended implementation cycle is roughly three years. A city scores itself, identifies weak indicators, builds policies and projects to improve them, and then re-scores to see what changed. This iterative loop is what turns the index from an academic exercise into a working planning tool.

How the index shapes urban planning 🔗

Beyond producing a score, the index influences how cities plan and budget. A multinational analysis of biodiversity plans by 39 cities found that actions linked to natural areas, public outreach, and partnerships were the most commonly mentioned, suggesting that the index helps cities prioritise visible, actionable interventions. The same study also found that while most cities included actions on many indicators, far fewer actually measured outcomes, pointing to a gap the index is designed to close.

The Singapore Index also creates a shared vocabulary. When a city in Latin America and a city in Southeast Asia both talk about indicator 1 (natural areas) or indicator 23 (outreach), they can exchange strategies meaningfully. This network effect has helped build a global community of urban biodiversity practitioners, with NGOs, universities, and consultancy firms increasingly collaborating with city governments on data collection and policy design.

The Hyderabad example 🔗

India’s most documented engagement with the index is Hyderabad’s. The city first applied the Singapore Index in 2012, around the time it hosted the eleventh Conference of the Parties to the Convention on Biological Diversity. It scored 36 out of 92 in that first round. Eleven years later, in April 2023, Hyderabad released its second assessment and secured 57 out of 92 marks, a jump of 21 points, making it the first city in the world to administer the index a second time.

The improvement was credited to large-scale interventions like the Telangana Ku Haritha Haram afforestation programme, the conservation and rejuvenation of lakes, and the expansion of urban lung spaces. Hyderabad now has more than 1,350 water bodies and significant rock formations as part of its natural heritage. Kolkata also applied the index in 2017, making it the second Indian city to do so. These examples show how the index can convert abstract environmental ambition into specific, trackable targets.

Global examples worth noting 🔗

Outside India, cities have used the index in distinct ways. Edmonton and Montreal in Canada have scored strongly on biodiversity monitoring, and the CBD’s handbook on the index credits this partly to their use of the Singapore framework. Singapore itself has used the index to guide its long-running transformation from a “Garden City” into a “City in a Garden”, weaving nature into roads, rooftops, and skyrise greenery.

Limitations and the road ahead 🔗

The index is powerful but not perfect. Data availability is uneven, especially in rapidly growing cities where biodiversity inventories may be incomplete or outdated. Some indicators rely on local interpretation, which can introduce variation in how they are scored. The original version also did not fully capture the connections between biodiversity loss and climate change, a gap the 2021 revision was specifically designed to address.

For Indian cities, scaling up the use of the index will require investment in local biodiversity surveys, GIS capacity, and inter-departmental coordination. State biodiversity boards, municipal corporations, and academic institutions all have a role to play. Linking the index to existing programmes like the National Biodiversity Strategy and Action Plan, the AMRUT urban mission, and Smart Cities Mission projects could anchor it firmly within mainstream urban governance.

As cities continue to grow, tools like the Singapore Index move biodiversity from a soft concern to a measurable, manageable dimension of urban development. The score is not the goal. The conversation, the planning, and the long-term ecological improvement it enables are what really matter.

What do you think? If your home city were to apply the City Biodiversity Index today, which of the three components – native biodiversity, ecosystem services, or governance – would score the lowest, and what one local change would do the most to improve it?

References

1. https://www.cbd.int/doc/publications/cbd-ts-98-en.pdf
2. https://eresources.nlb.gov.sg/infopedia/articles/SIP_1765_2011-02-11.html
3. https://iucnurbanalliance.org/launch-of-the-new-look-singapore-index-on-cities-biodiversity/
4. https://southasia.iclei.org/news/hyderabads-city-biodiversity-index-illustrated-natural-asset-map-released/
5. https://www.nlb.gov.sg/main/article-detail?cmsuuid=88701e9d-a9e3-4839-9c16-e142de9fcbd8
6. https://iucnurbanalliance.org/tools_and_resources/singapore-index-on-cities-biodiversity/
7. https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0235773
8. https://telanganatoday.com/hyderabad-performs-well-in-city-biodiversity-index-2022
9. https://thesouthfirst.com/telangana/hyderabad-becomes-the-first-city-to-create-biodiversity-index-for-a-second-time/