More than half of the world’s population lives in urban areas, and the number is assumed to increase to two thirds by 2050. Cities are centers of commerce, generating more than 80 percent of global GDP, and play an essential role in advancing productivity needed for economic development. Urbanization can make it easier to place the required infrastructure for essential services such as grid-connected energy, water and sanitation. However, urbanization also causes vast challenges.
All over the world, cities are confronting critical levels of air pollution. Many cities in developing countries face rapidly growing numbers leading to slum dwellers and unplanned urban sprawl as infrastructure provision has not kept pace with population growth.