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The shift from rural to more urban societies is a global trend with significant consequences for greenhouse gas (GHG) emissions and climate change mitigation. Across multiple dimensions, the scale and speed of urbanization is unprecedented: more than half of the world population live in urban areas and each week the global urban population increases by 1.3 million. Today there are nearly 1000 urban agglomerations with populations of 500,000 or greater; by 2050, the global urban population is expected to increase by between 2.5 to 3 billion, corresponding to 64% to 69% of the world population (robust evidence, high agreement). Expansion of urban areas is on average twice as fast as urban population growth, and the expected increase in urban land cover during the first three decades of the 21st century will be greater than the cumulative urban expansion in all of human history (medium evidence, high agreement). Urban areas generate around 80% of global Gross Domestic Product (GDP)(medium evidence, medium agreement). Urbanization is associated with increases in income, and higher urban incomes are correlated with higher consumption of energy use and GHG emissions (medium evidence, high agreement)[Sections 12.1, 12.2, 12.3].