Although cities occupy only 2 per cent of the world’s crust, 53 per cent of the global population resides in them. Cities also account for 80 per cent of global GDP, and 600 of these cities are home to 20 per cent of the world’s population, generating 60 per cent of global GDP (Dobbs et al., 2011). At the same time, 33 per cent of all city dwellers live in slums and cities are also a vast consumer of resources, producing 75 per cent of world CO2 emissions. So, cities rule yes, but some cities are more equal than others and which ones rule is set to change. By 2025, according to Dobbs et al., the membership of the group of the top

600 cities will change as the momentum for migration moves from the developed nations to the south and east and overwhelmingly from China (e.g. Guiyang) as well as India (e.g. Surat) and Latin America (e.g. Cancún). This change is also anticipated to result in a further concentration of growth with a new top 100 cities contributing to approximately 33 per cent of GDP growth. More than this, though, the trend for ‘midsized’ cities (150,000 to 10 million inhabitants), as opposed to ‘mega’ cities (more than 10 million inhabitants), to deliver most growth will continue and increase to the point they will deliver 40 per cent of global growth by 2025 (Dobbs et al., 2011). To put the power of cities in context, it is interesting to compare their economic

might to that of nations and big business, as detailed in Table 7.1, an extract from the world’s top 100 economies of 2008.