A Synthesis of Global Urbanization Projections

This chapter reviews recent literature on global projections of future urbanization, covering the population, economic and physical extent perspectives. We report on several recent findings based on studies and reports on global patterns of urbanization. Specifically, we review new literature that makes projections about the spatial pattern, rate, and magnitude of urbanization change in the next 30–50 years. While projections should be viewed and utilized with caution, the chapter synthesis reports on several major findings that will have significant socioeconomic and environmental impacts including the following: By 2030, world urban population is expected to increase from the current 3.4 billion to almost 5 billion; Urban areas dominate the global economy – urban economies currently generate more than 90 % of global Gross Value Added; From 2000 to 2030, the percent increase in global urban land cover will be over 200 % whereas the global urban population will only grow by a little over 70 %. Our synthesis of recent projections suggest that between 50%–60% of the total urban land in existence in 2030 will be built in the first three decades of the 21st century. Challenges and limitations of urban dynamic projections are discussed, as well as possible innovative applications and potential pathways towards sustainable urban futures

Trade-offs and synergies in urban climate policies

International audienceCities are at the forefront of climate policies(1-6). However, urban climate policies are not implemented in a vacuum; they interact with other policy goals, such as economic competitiveness or social issues. These interactions can lead to trade-offs and implementation obstacles, or to synergies(7,8). Little analysis investigating these interactions exists, in part because it requires a broad interdisciplinary approach. Using a new integrated city model, we provide a first quantification of these trade-offs and synergies, going beyond the qualitative statements that have been published so far. We undertake a multicriteria analysis of three urban policies: a greenbelt policy, a zoning policy to reduce flood risk and a transportation subsidy. Separately, each of these policies seems to be undesirable because each one negatively affects at least one of the different policy goals; however, in a policy mix, the consequences of each policy are not simply additive. This nonlinearity permits building policy combinations that are win-win strategies. In particular, flood zoning and greenbelt policies can only be accepted if combined with transportation policies. Our results show that stand-alone adaptation and mitigation policies are unlikely to be politically acceptable and emphasize the need to mainstream climate policy within urban planning

Urban Biodiversity and Climate Change

Urban biodiversity refers to the variety and variability among living organisms found in a city and the ecological systems in which they occur. Overall, urban biodiversity responds to a combination of biogeographic and anthropogenic factors, with a strong influence of the latter. In a rapidly urbanizing world under the pressing threat of climate change, there is a growing interest in understanding how cities benefit from local biodiversity and how these benefits can be under threat due to climate change. This chapter addresses how the combined effects of climate change and urban factors affect urban biodiversity and the practical steps cities are taking to incorporate biodiversity issues in their development agendas