About Michael Batty

I chair CASA at UCL which I set up in 1995. I am Bartlett Professor In UCL.

The Prevalence, Scaling and Variance of Urban Phenomena

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This coming month (January 2017) sees the launch of another of Nature’s flagship journals Nature Human Behaviour. In it, Andres Gomez-Lievano, Oscar Patterson-Lomba, and Ricardo Hausmann explore an integrated model which explains the prevalence, scaling and variance of urban phenomena in which they suggest a new theory of city size that embodies ideas from economic complexity and cultural evolution. This provides a rich basis for speculating on the economic structure of cities suggesting hints as to how old cities might regenerate their past prosperity and new ones generate more success. They do not dwell on applications for they are most careful to ground their argument in caveats – largely due to the fact that they make many plausible but non-testable assumptions to generate their model. In fact, this is little different from most work in the urban systems (and indeed in economic science) where bold assumptions are always necessary to cut through the richness and noise that plagues our understanding and descriptions of human behaviour.

I have written and News and Views comment on this and you can find it here. In fact, the article that this is a response too, is also available for gratis – Nature’s first issue is essentially downloadable for free –  you can get their article by clicking here. What they essentially do in the paper is demonstrate how scaling arises due to the economic complexity of any city. They ground their work in the key result that as cities get bigger, they get more than proportionately more wealthy, implying a scaling law that is consistent with old ideas about urban agglomeration but which was demonstrated nearly 10 years ago for US cities by Bettencourt; but a law with much more ambiguity when it comes to measuring the wealth of older and more polycentric city systems such as those in the UK. To this end, and I quote from my review: “ … they introduce a simple but enticing model which extends these scaling laws to embrace the prevalence of how different activities scale with city size. First, activities will become less prevalent across all cities as they get bigger. Second, they will become relatively more concentrated in bigger cities, on the average. And third, the deviations from this average will widen. Their theory and the model that comes from this suggests that as an activity requires more and more inputs of both a general and specialized nature, it will become less prevalent as a city gets bigger. But as cities get bigger, only then can they access more inputs; so the theory predicts that the prevalence of more complex and specialized activities will also become more concentrated. To an extent, this increase in the numbers of factors or inputs with city size is consistent with their related ideas on economic complexity. A consequence of the way they structure the model is that the variation in the degree of prevalence for a city will increase as the activities get more complex while the total prevalence of the activity gets less.”

There is a lot more than they say in their article and you should read it as it takes a different view of economic systems, technological progress and cultural affinities than anything that has come before. But it is consistent with a good deal of more general thinking about the nature of cities such as that contained in the writings of Jane Jacobs for example. Exciting times for cities and city planners.

Confronting Vulnerability and Violence in the Urban Century

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Did you know that there were more murders in the US-Mexico border town Ciudad Juarez in 2010 than civilian deaths in the whole of Afghanistan – 3111 compared to 2421. Mike Batty gave a talk at this meeting which was organised by the the University of Pittsburgh’s Ridgway Center for International Security Studies in the Graduate School of Public & International Affairs from November 13-15, 2016. He talked about how complexity might be used to help articulate questions of fragility and resilience associated with violence in the cities of the global south. This was a free ranging seminar with a strong strategic dimension and it introduced ideas about feral cities and fragile cities as well as descriptions and analysis of many different. Phil Williams, an expert in international security talked about different types of cities, introducing the idea of feral cities – a term first used by Richard Norton from the Naval War College – to describe cities that were on the edge of lawlessness but still connected to the global economy in diverse ways – Mogadishu comes to mind – and then John de Boer presented ideas about fragile cities – again cities on the edge whose core functions were under threat. There was much talk about resilience, vulnerability and fragility with Desmond Arias introducing the notion that cities might be resilient but pernicious – caught in the trap of being sustainable but undesirable places to live. A great seminar. You can read my own contribution here but like all good seminars, it needs to be rewritten in the light of what I learned here.

In the Shadow of Darwin

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Michael Batty is working on a project with colleagues from the University of Melbourne, UNC at Chapel Hill, and the Santa Fe Institute at the Galapagos Science Centre with the Universidad San Francisco de Quito. They are exploring the way human populations are interacting with the natural ecosystem. The Islands are facing enormous population pressures from ecotourism and the group are modelling these interactions between the coupled human-natural systems using the science of complex adaptive systems (CAS).  Eventually they will produce a book about these pressures and their impact on the fragility of the ecosystems making suggestions for future change. The notion that the human and natural ecosystems remain in equilibrium is a convenient fiction and the idea that the Galapagos would have remained the same since Darwin’s historic landing in 1835 (described in his The Voyage of the Beagle) if no human populations had resided on the islands, is fanciful. Natural ecosystems evolve perhaps at a slower rate than human populations at least in terms of their migration, growth and change but these coupled systems pose special problems which have wide implications for cities and nature. The challenges for us all are enormous. They lie at the cutting edge of science and human affairs.

The pictures above show Darwin’s first landing site on the Galapagos Islands in 1835.