Defining Urban Geochemistry. Issue 49 (9th December 2014) - Gardner, Christopher B.
Abstract From 1950 to 2014, the proportion of the world's population living in urban centers has increased from 30% to 54%, and the United Nations' World Urbanization Prospects: The 2014 Revision estimates this number will reach 66%, or 6.3 billion, by 2050. Nearly 90% of this growth is projected to occur in Africa and Asia, which today remain mostly rural.