Cities, with their distinctive processes and problems, are major features of the modern world. Comparative approaches in the global context permit to focus on their properties, the social, economic and environmental issues they pose, and to evaluate the utility of political and societal solutions to their problems. In this respect, ten specific urban challenges can be identified:

1- Complex Urban Systems
Urban systems have seen radical changes in recent decades and will continue to do so. How are various national, continental and global urban systems changing – particularly in relation to such features as city size, economy, migration, interaction, linkage, communication, transport and control functions? What processes and differential development paths are involved and how have different government policies affected these changes? This work must be extended to incorporate updated national and international comparisons and recognize the accelerated growth of a limited number of global command centers in the highly connected world of electronic communications, finance, trade, and rapid travel. In addition, we must seek solutions for those cities that are left behind by these changes.

2- Technological innovations, creative activities in cities, innovative and smart building and transportation in cities
Urban economies are evolving quickly, with the growth of the “service” sectors and new activities in science, technology, commerce, communication, media, art and design. Why do these activities concentrate in some cities and how do these new “clusters” integrate within existing economic, social and environmental contexts? Can we quantify “smart cities” or identify “creative activities”? Can one identify cycles in these economic trends? As a result of new technologies are all cities become “smart”? Does this “smart” growth benefit the entire city or does it increase polarization and fragmentation? Does it alter the morphology and structure of urban areas and can it lead to new forms of urban society?

3- Polycentrism, small and medium size cities
At national or regional scales, small and medium size cities have very different issues depending on their proximity to large cities. In remote areas, small and medium size cities often lack higher education, and advanced services, that lead many young people to leave never to return. These places find it difficult to attract investment and are often by-passed in favor of larger more accessible locations. How can these places find new dynamism? Can they counter increasing concentration in metropolises? Can they provide an alternative approach or insight for sustainable urban systems? On the other hand if one focuses on a more city-region scale, small and medium size cities around the metropolises constitute new urban spaces such as “edge” or “edgeless cities” that remain under the influence of the central metropolis. What is the future of such places? To what extent are new polycentric patterns emerging and what is the likely impact on sustainability and spatial equity?

4- From Sustainability to resilience
Can sustainability be tackled at the urban scale? Sustainability needs to think more about the capacity of cities to adapt their structure in order to accompany social and economic changes. What progress is being made by cities around the world in the development of new programs and policies to create more environmentally and socially sustainable areas? How can these solutions be evaluated at various spatial scales? What are the emerging best practices in cities, from smart growth to green solutions etc., and what are the governance problems that restrict progress in implementing more effective policies promoting resilience at intra and inter-urban scales?

5- Dilemmas of Aging Cities
A serious new problem has emerged in some cities of the developed world. The declining birth rate of industrialized countries is creating many settlements with increasingly aging and declining populations. What are the effects of this trend upon the functions and character of these cities, especially their infrastructures and levels of social provision? What policies are emerging in cities around the world affected by this problem to cope with these changes? How can so-called “shrinking cities” manage their future?

6- Urban Governance, planning and participative democracy
It is an unfortunate, but undeniable, fact that most large urban agglomerations are not permitted to govern themselves. Control over revenues and investments is shared with other levels of government and/or fragmented among dozens of small municipal units within the metropolitan area. Inevitably these political arrangements affect the spatial structure of infrastructure and public services, including planning. We must explore the spatial issues that detract from good urban governance, and investigate the utility of emerging administrative solutions seen in many countries, such as the ‘new regionalism? that seeks to provide a new spatial solution to the provision of services. In parallel, citizens are becoming more organized and becoming more active and involved in decision making at the neighborhood level. This activism affects the way urban planning functions and is bound to have impacts on cities in the future. This will also affect urban areas beyond the traditional city.

7- Contested Social Spaces
The increasingly multi-layered social and ethnic character of cities has led to more intricate life spaces within cities, and increased the potential for conflicts among various groups. Since many communities, made up of either Diasporas or cosmopolitans, exhibit strong intra-community cohesion, this may threaten other communities. How can we measure these new patterns and changes and make effective international comparisons? Where and when do conflicts emerge? How can differences between the various actors in these spaces be reconciled, ensuring that local communities are themselves empowered, rather than simply passive recipients of change from forces beyond their control? Is it possible for all groups to live in tolerance with one another?

8- Increasing Insecurity
In the past, cities survived because of their ability to create secure environments for their citizens. In many contemporary cities crime rates, anti-social behavior and ethnic conflict threaten to make them less liveable, despite higher levels of surveillance, and apparent solutions such as gated communities, which create more private spaces and segregation. Part of the explanation for these trends may be unequal income distributions in which the lower income groups struggle to survive or maintain their position and the wealthy create exclusive areas. Several key problems emerge from these changes. How we can best conceptualize and measure these new forms of insecurity and more compartmentalized spaces? How do we make international and national comparisons of the increasing inequalities within cities and the levels of insecurities? Can we apply the best practices from cities that have successfully overcome these problems to other cities and societies, as well as linking these problems to our understanding of the new forms of urban social space?

9- Urban Heritage and Conservation
The distinctive identity of many cities and societies depends upon their historical heritage, as expressed in their built fabric. How can these identities be understood and interpreted? What are the policies that support the preservation of these heritages, yet still provide livable and affordable spaces in these areas, instead of allowing historic areas and city centers to be overwhelmed by homogenized tourism?

10- New concepts and methods in urban studies
As the world changes there seems to be more and more data and more and more things to measure. There are new forms of economic activity, increasing levels of personal and corporate communication, increasing mobility of capital and people, increasing levels of internet usage, increasing levels of e-commerce, and increasing levels of electronic participation in democracy. All of these have the potential to transform the inter and intra-urban realms in which we live. Big data may help our understanding of many urban problems, but there is also a need for increasing conceptual and methodological sophistication to deal with these changes. New theories, approaches, methods and techniques are needed if we are to fully understand the urban world of the twenty-first century.

Authors

Céline Rozenblat Chair of the Urban Geography Commission of the International Geographical Union (IGU) http://www.unil.ch/igu-urban

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