City sustainability ranking must be treated with caution, but act as a fillip for reform

Spring means many things for urban geographers, but one is a slew of rankings of the world’s cities, whether for growth, liveability, smartness or even sustainability. As urban environments continuously evolve, it is of course essential to regularly examine whether and how they work, focusing on the effectiveness of public services and how local insights can address emerging urban challenges.

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City performance evaluations have become a global trend, with both public and private organizations developing comprehensive ranking systems. These measurement tools claim to provide guidance for local policymaking, with a particular focus on sustainability initiatives. The rankings reflect an underlying competitive dynamic where cities strive to demonstrate their economic potential and attractiveness.

Each index is supported and funded by an organisation that will have its own agenda and priorities and therefore must be viewed through that lens. The Happy City Index from the Institute of Quality of Life, a new think tank devoted to understanding and enhancing the quality of life in urban areas. It takes its inspiration from Plato’s comment in The Republic that “this City is what it is because our citizens are what they are”. It places Copenhagen first, followed by Zurich and Singapore.

The World’s Best Cities by Ipsos and a consultancy called Resonance, has ranked cities according to which is, err, the best. Using a combination of core statistics and user-generated data from online sources such as Google, Tripadvisor and Instagram to measure liveability, lovability, and prosperity, it puts London first, followed by New York and Paris.

Then there is IESE Business School's 2025 Cities in Motion Index which assesses urban centres globally, examining their sustainability and citizen well-being across nine critical dimensions. For the third consecutive year, London has been crowned the world's most intelligent city, with New York and Paris secured the second and third places, respectively

But as this blog looks at sustainability, what might world cities look like when ranked on that measure? The proliferation of urban ranking systems has been significant in recent years. One of the best known as The Arcadis Sustainable Cities Index that has been running for a decade. Developed in collaboration with the United Nations Human Settlements Programme (UN-HABITAT), it uses the widely accepted three core pillars of sustainability of the environment, society and economy that it calls Planet, People and Profit.

The assessment for this year is not out yet but 2024’s gives the top five places to western Europe. Amsterdam tops the table, followed by Rotterdam, Copenhagen, Frankfurt and Munich. The next one is expected in June.

One academic research team examined 21 different urban sustainability rankings, focusing on their methodological approaches and underlying mechanisms. The study revealed several critical limitations in these evaluation tools. Specifically, the rankings often oversimplified complex urban dynamics, lacked transparency in their data collection and scoring processes, and demonstrated inherent biases.

As the authors state, city rankings, benchmarks and indexes have become a central instrument for assessing and monitoring cities, with the implication that planners, investors and potential residents will take decisions based on the rank placings. The primary issue is that public presentations of results tend to emphasize the final numerical score while largely overlooking the critical methodological foundations. In other words, there is not enough focus on the methodology — or the black box as they call it — that is used to produce the rankings.

They find that the publicly available information is insufficiently detailed to enable a comprehensive assessment of the scientific integrity of these measurement and monitoring tools. Moreover, the complex analytical mechanisms make it extremely challenging — if not entirely impossible— to critically examine how a city's specific score is actually derived.

These methodological shortcomings have notable consequences. The rankings tend to marginalise poorly performing cities and inadvertently reinforce existing urban stereotypes. The findings highlight the need for more nuanced and comprehensive approaches to understanding urban performance and sustainability.

However, ranking can play a role if they act as an incentive for city leaders to raise their game and take steps that will raise their ranking by improving conditions for residents on the ground. Of course, the “black box” concerns apply here, but if the reforms are focused then an uplift in the ranking can be a sign for business, investors and potential residents to come to that city in pursuit of greater sustainability.

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