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Welcome to today’s What is The Future For Cities podcast and its Research episode; my name is Fanni, and today I will introduce a research paper by summarising it. The episode really is just a short summary of the original paper, and, in case it is interesting enough, I would encourage everyone to check out the whole paper.

Our summary today works with the article titled Review of sustainability indices and indicators: Towards a new City Sustainability Index from 2012 by Koichiro Mori and Aris Christodoulou published in the Environmental Impact Assessment Review journal. Since we are investigating the future of cities, I thought it would be interesting to see how the different sustainability indices work and whether a new is needed to better assess urban sustainability. This article investigates whether a new sustainability index is needed, enabling to assess and compare cites’ sustainability performance in order to understand the global impact of cities on the environment and human life as compared with their economic contribution.

Cities and urban developed areas with large population are important worldwide because human social and economic activities have been concentrating there. And despite their economic and social roles, they perform poorly in terms of environmental conservation. Therefore, it is significant to evaluate sustainability in cities in order to appropriately manage human activities there. In general, the sustainability assessments try to evaluate individual projects, policies, plans and programs regarding sustainability as an explanatory or planning tool, while the proposed new city sustainability index tries to evaluate city sustainability as a performance evaluation tool.

Sustainability has already been a popular term in environmental economics, but its definition is still ambiguous, while urban sustainability even has special characteristics. The starting point is the Brudtland Report from 1987: sustainable development is one that meets the needs of the present without compromising the ability of future generations to meet their own needs. How this understanding is translated to different fields, however, is not agreed, not even in the fields. There are approaches of weak or strong sustainability, intergenerational responsibility, non-declining consumption and non-declining utility over long term, connecting economy, quality of life, ecosystems and natural resources.

Based on the many understandings, Mori and Christodoulou found shared notions for sustainability, although they acknowledged the difficulty to define sustainability precisely and convincingly. Sustainability consists of two main elements: the triple bottom line as an abstract notion of environmental, social and economic processes and intergenerational equity. Therefore, the sustainability index needs to

• Consider the triple bottom line – environmental, economic, and social dimensions,
• Maintain the equity between current and future generations, among current people and between humans and nature
• Maintain healthy conditions related to the first two on the long run.

The process of sustainability assessment itself can help to identify the issues that can be improved, especially when it is conducted in a comparative way and when the elements of sustainability, such as indicators, can be distinguished and compared to thresholds, because what is measured, gets managed.

However, the problems start with defining the city. There are many different approaches to the city itself, based on population, land use, density, political boundaries. This last one, the political boundaries though may be arbitrary and without any consideration to geography or natural limits, is the most useable in terms of data gathering. Data is gathered in these bureaucratic and administrative boundaries, and it tends to be better managed in these fields than outside of them.

Combining these two wage definitions of sustainability and cities into urban sustainability also creates a vague concept, and its assessment is still ambiguous. Therefore, the authors chose their own two core conditions for urban sustainability assessment: to judge whether cities are sustainable in terms of environmental, economic and social dimensions respectively, and to evaluate both direct and indirect external impacts and dependencies of a city on other areas beyond the city boundaries. This latter one, the external impacts are important because a city concentrates on economic development within it and depends on other areas for supply of resources and food, disposition of wastes, emission of pollutants, indirect use of ecosystem services, and so on. Finally, the difference between developed and developing countries also need to be taken into account as the resources, approaches, needs and focuses can be very different in those regions.

To see whether a new city sustainability assessment tool was required, the authors reviewed the major sustainability indices and indicators. They evaluated the indices whether they satisfy the two conceptual requirements of working with the external impacts and the triple bottom line, then categorised their methodology into single or multi-indicators based, and they investigated whether they assess sustainability in regards to developing and developed countries.

The reviewed indices were:

• Ecological Footprint
• Environmental Sustainability Index
• Dashboard of Sustainability
• Welfare Index
• Genuine Progress Indicator
• Index of Sustainable Economic Welfare
• City Development index
• Emergy/exergy
• Human development Index
• Environmental Vulnerability Index
• Environmental Policy Index
• Living Planet Index
• Environmentally-adjusted Domestic Product
• Genuine Saving,
• And some applications of composite indices and multivariate indicators to local or regional context as case studies.

The investigation showed that there is no sustainability assessment which satisfies both the external impacts and the triple bottom line requirements. There were indices covering them separately, and even not covering them at all. Only a few indices compared sustainability among world cities in both developed and developing countries. Based on these findings, Mori and Christodoulou concluded that a new city sustainability assessment tool is required.

The authors continued with a few key points for the new tool:

• Since the biophysical limits to sustaining life on Earth are absolute, sustainability should not be relativistic, but measured on absolute biophysical and ecological standards and thresholds, even if considering these on different levels such as general, global, and local on the country level.
• It is important to distinguish between the total environmental impact and eco-efficiency, depending on environmental indicators, because total environmental impact is still largely due to large population.
• It is avoidable to ranking cities by a synthesized index, a composite index or a single indicator.
• Finally, although agent-based modelling can be very beneficial, it is also time-consuming and requires huge amount of data which may not be available.

Based on the findings here, the new City Sustainability Index is required, assessing the triple bottom line and the external factors, must have the original purpose to assess city sustainability, and acknowledge the differences between developed and developing countries. With the key points, these are the reasons to create a new assessment tool in order to assess and compare cities’ sustainability performance and to provide local authorities with guidance towards sustainable paths.

As the most important things, I would like to highlight 3 aspects:

1. Sustainability started from the definition of the development that meets the needs of the present without compromising the ability of future generations to meet their own needs, and thrived into many different understandings.
2. Sustainability needs to be based upon its triple bottom line: social, environmental and economic sustainability, while also considering the external factors and intergenerational effects.
3. City and urban sustainability assessment tools are created for helping decision making – and not to create a competition among cities around the globe.

Additionally, it would be great to talk about the following questions:

1. Why do these assessment tools turn into competitions? The victors usually praise the results, while losers deny, contest and question the results, and they rarely result in change.
2. Do we need to assess sustainability absolutely or relatively? Why?
3. How does the original definition of sustainability change your approach to it?

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