Megacities – cities with more than 5 Mio. inhabitants – are new phenomena of worldwide urbanisation processes. They are results of globalisation and are subject to global ecological, socio-econo¬mical, and political change. Reciprocally, they also dictate these changes due to their strong developmental dynamics. New are not only the up to now unknown dimensions of the quantitative enlargement, the high concentration of population, infrastructure, economic power, capital, and decisions, as well as the exces¬sive and partially self-energising acceleration of all the development processes, but above all also the simultaneousness and overlapping of the different processes with mutual feedback. Increasingly, megacities are subject to an up to now unknown loss of governability and control – with the consequence that more and more processes are unregulated and take place infor¬mally. They are driven and shaped by manifold decisions of numerous urban actors, from administration to non-governmental agencies, from transnational corporations to civil society.

Megacities have developed into new forms of socio-economical and political urban entities, they are “laboratories of the future“, because they reflect glo¬bal development trends compactly. Therefore, it is not the mega-urban development per se, but rather the dynamics, complexity and multi-actor dependency of the fundamental processes as well as their economical, social, and spatial effects, which form one of the greatest challenges of our time.

Too often, megacities are perceived mainly as burdened by numerous disadvantages, origins and motors of multiple problems as well as agents and victims of risks. Such a view does, however, neglect numerous – at least potential – benefits, chances and advantages of mega-urban developments. Consequently, in a more balanced perception megacities possess a so-called double-headed face:

  • On the one hand, megacities are global risk areas - in natural and human dimensions. They are subject to increasing socio-economic vulnerability due to increasing poverty, socio-spatial and political-institutional fragmen¬tation and often extreme forms of segregation, disparities, and conflicts. Megaurban societies are disintegrated and destabilised due to the direct proximity of very different local livelihoods and lifestyles (including ethnic and social groups). Megacities not only face risks in consequence of external events, whether natural or manmade. They likewise contain, produce and reinforce hazards and as such are "victim and culprit" at the same time.
  • On the other hand, megacities, as global junctions, offer a multitude of potentials for global transformation. Due to their wide range of available human resources and globally linked actors, megacities are considered to be potential “innovative milieus“. For example, improved sustainability can be achieved by decreasing the "drain on land resources", by using resources very efficiently (recycling and regeneration), efficient hazard prevention, and sufficient health care.
The general perception of mega-urban regions, the international megacity research as well as the priorities in planning and governance need substantial changes. On different levels the following shifts in prioritisation deem to be important:

  1. Megacities should more being perceived as areas of global importance, affected by and affecting themselves manifold levels of global change over wide distances and long periods of time. Consequently, their performance falls no longer just in the responsibility of local actors, but as they are embedded at least in transnational, if not global development processes the responsibility for their sustainable development lays in the hands of numerous, more or less directly or indirectly responsible, internationally connected actors.


  2. The comprehension of the “double-headed face” of mega-urbanisation demands that the general perception of megacities should shift from a predominantly negative view (“moloch”, “global sink”) to a more positive perception of mega-urban areas as priority areas and drivers of change, with at least often undiscovered potential of improved sustainability and quality of life for many, at least more, if not all inhabitants. Megacities are key areas of sustainable urban development worldwide.


  3. The complex reality of phenomena, processes and actors as well as the high pace of development in mega-urban areas inevitably demand international, inter- and transdisciplinary, intercultural as well as multi-stakeholder-oriented action – including stakeholders from research, administration, the private sector and the general public and civil society. The high dynamics of urban land markets and the increasing relevance of private land developers make them important stake holders in negotiation processes of urban governance. This necessarily implies a more engaged and committed interaction among all responsible levels.


  4. As to the role and direction of research, the generation of not only knowledge based on fundamental descriptions, analyses and explanations but, moreover, the creation of knowledge for prediction, orientation and decision-making is deemed indispensable.


  5. For many megacities, particularly in the developing countries, major shifts from a predominantly globalisation-driven, competitiveness-seeking top-down development to alternative priorities are regarded important. These include the turn to three key components: Beyond current priorities on structure-, pattern-, landuse-, infrastructure- and housing-based planning more problem-, process- and people-oriented approaches are needed.