Home / Blog / Bigger cities bigger emission, not necessarily true

Bigger cities bigger emission, not necessarily true

Distribution of major world cities based on their population density versus carbon footprint. Image credit: Global Gridded Model of Carbon Footprints

An interesting article by the World Economic Forum discusses the carbon footprint of cities, an important topic as we are striving to reduce the human society carbon footprint on the planet with the (ambitious) goal to become carbon neutral by 2050 (this is not as good as it might seem, since we have already increased the carbon level in the atmosphere over the last 200 years, with a sharp acceleration in the last 50 and we will continue to increase this level until 2050, assuming we can meet the neutrality goal!).

Cities, and we are clustering more and more in cities (we have passed the 50-50 level -50% in rural, 50% in cities- in the first decade of this century, in 2018 55% of population lived in urban areas, a figure expected to rise to 68% in 2050), are a major contributor to the global carbon footprint contributing for about 68% of the total even though they are hosting less than 60% of the global population.

The contribution to emission is not uniform: the top 100 urban areas host 11% of the world urban population but contribute for 18% to the global carbon footprint. Hence, it would seem that the “bigger” the city the more incidence of carbon emission (they contribute more than what you would expect if there was a linear relation between population and emission). In this sense the bigger the city the less efficient in terms of eco-friendliness.

However, the study of the WEF, using data on 13,000 cities gathered by the Norwegian University of Science and Technology, shows that this is not necessarily true: a city can become big and remain eco-friendly.

Consider the graphic: Cities like Cairo (2.5 Mt of  CO2 per million people) and Jakarta(2.3 Mt of  CO2 per million people)  have a much lower carbon footprint pro-capita than other cities like Seul (12.6 Mt of CO2 per million people) or Dubai (24 Mt of CO2 per million people).

At first glance it would seem that the reacher a city is (the more pro-capita GDP) the more un-wise its behaviour in eco-terms. This is confirmed by the study. In a way it is sad to notice that those areas that are reacher and thus have average higher eduction and means to curb carbon emissions are the ones that are polluting more.

London may be seen, among rich cities, one that is behaving better with 10Mt of CO2 per million people, still 5 times more than Cairo but way less than Dubai. The best in class among the big metropolis is Tokyo Yokohama, with a 4.1Mt of CO2 per million people, more than Cairo but with a much higher GDP and quality of life (in terms of services).

This will have to change in the coming two decades if we are to reach carbon neutrality by 2050. Technology, unfortunately, has been one of the major driver in CO2 emission, both directly an indirectly. It is time to use technology to take care of the environment and this requires a global cultural change and a very strong political commitment.

About Roberto Saracco

Roberto Saracco fell in love with technology and its implications long time ago. His background is in math and computer science. Until April 2017 he led the EIT Digital Italian Node and then was head of the Industrial Doctoral School of EIT Digital up to September 2018. Previously, up to December 2011 he was the Director of the Telecom Italia Future Centre in Venice, looking at the interplay of technology evolution, economics and society. At the turn of the century he led a World Bank-Infodev project to stimulate entrepreneurship in Latin America. He is a senior member of IEEE where he leads the New Initiative Committee and co-chairs the Digital Reality Initiative. He is a member of the IEEE in 2050 Ad Hoc Committee. He teaches a Master course on Technology Forecasting and Market impact at the University of Trento. He has published over 100 papers in journals and magazines and 14 books.