Lewis Dijkstra from the European Commission in this lecture explains why without a global definition of cities, urban indicators are hopelessly distorted and proposes the degree of urbanization as new method to solve this problem.
Issues which the lecture addresses
The boundary of a city will have a big impact on the indicators linked to the urban Sustainable Development Goal. For example, a narrow definition focussed on the city centre will lead to poor scores on air quality and the presence of open or green space, but it will give better scores for access to public transport. Also measuring changes over time will be influenced by where the boundary is drawn as most growth occurs at the fringes of a city. The degree of urbanisation is based on a population grid of 1 sq km that overcomes the problem of the differences in municipal geometry. It identifies three degrees of urbanisation: (1) cities, (2) towns and suburbs and (3) rural areas.
Short analysis of the above issues
To help cities learn from each other, the EU and the OECD wanted to find a harmonised definition of a city. This led to a new definition which has been implemented in all EU countries and most non-EU OECD member countries. Now Eurostat, the statistical offices for the EU, publishes over 100 indicators by degree of urbanisation and a wide range of indicators per city. The big stumbling block to a harmonised definition was the difficulty to identify cities that were part of a much larger municipality (which consequently had a very low population density) or that were spread across multiple municipalities. A new tool, the population grid allowed us to overcome these obstacles.
Propositions for addressing the issue
(1) Why is it important to have a global definition of cities? The lecture shows in a clear, visual manner the problems linked to differences in city definitions. It is presented as a discussion between two mayors (Brad from Broadville and Nell from Narrowtown).
(2) The impact on the indicators linked to the urban SDG are demonstrated both for measurements for a single point in time and changes over time. This demonstrates that all these indicators are highly sensitive to where the boundary is drawn (the so-called modifiable areal unit problem).
(3) How does the degree of urbanisation work? The lecture explains step by step how the degree of urbanisation can be applied.
(4) What were the main lessons from the experience with this new definition in the EU over the past five years? The lecture explains how this new definition has helped to produce better and more data for cities.
(5) How do the results of this new method look when applied to the globe. This builds on the work done for the State of European Cities Report, 2016 where the first chapter analyses and describes the 13,000 cities in the world identified using their degree of urbanisation.
Lewis Dijkstra is the deputy head of unit of the Analysis Unit of the Directorate-General for Regional and Urban Policy, European Commission. He is the editor and main author of the Cohesion Reports. These focus on the regional and urban dimension of economic, social and environmental issues. His latest work and publications included cover topics such as the development of metropolitan regions in the EU, population change in remote rural regions, labour mobility in the EU and the US, regional competitiveness and quality of government.
ADDITIONAL READING MATERIAL
The first chapter of the State of European cities report describes results of using the degree of urbanisation at the global level: http://ec.europa.eu/regional_policy/en/policy/themes/urban-development/cities-report
The Atlas of the Human Planet explains how the degree of urbanisation was applied to the globe: http://ghsl.jrc.ec.europa.eu/atlasOverview.php
This interactive map show the degree of urbanisation anywhere in the world as well the presence of built-up areas and population grids: http://ghsl.jrc.ec.europa.eu/visualisation.php
The global data can be downloaded here: http://ghsl.jrc.ec.europa.eu/data.php
The OECD report on metropolitan area definition: http://www.oecd.org/regional/redefiningurbananewwaytomeasuremetropolitanareas.htm
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The Global Urban Lecture series is an initiative by UNI – UN-Habitat’s partnership with universities worldwide.