The contours of a new urban world? Megacity population growth and density since 1975

The problems posed by rapid and large-scale urbanisation are manifold, and are recognised in the UN’s New Urban Agenda; a declaration of intent that aims to meet such challenges head-on facilitated by the systematic tracking and analysis of global urban growth and change. In this context, the release in 2016 of new small area Global Human Settlement Layer (GHSL) data was said to represent a unique opportunity to facilitate comparative global analyses of urban change dynamics and, perhaps somewhat idealistically, move forward progressive planning agendas. We therefore focus on population growth and density in 30 major urban agglomerations using the GHSL in order to shed light on the scale and extent of global urbanisation over the past four decades and to interrogate the potential role of the GHSL in tracking urban change.