In pursuit of sustainability – Spatio-temporal pathways of urban growth patterns in the world's largest megacities

Governing the future growth of the world's megacities towards higher land use efficiency is important for achieving global sustainability. We have computed statistics of the urban growth modes of 33 megacities (with ten-million-plus population) worldwide for two periods (1985-2000 and 2000-2015) and performed a hierar-chical cluster analysis to examine their urban growth patterns. Results reveal that urban growth has mostly occurred through edge expansion but also that its relative dominance has decreased due to the rising shares of the infilling and outlying growth modes. Based on the co-occurrence and changing dominance of these three urban growth modes over time, four pathways of urban growth patterns are identified- oscillating/ping pong, transition-to-densification, transition-to-sprawl, and extensive sprawl. The majority of megacities followed the oscillating/ping pong pathway, which is dominated by edge expansion and altered phases of infilling and outlying growth. However, by indicating a clear shift from edge expansion towards infilling as the dominant pathway of urban growth, the transition-to-densification pathway appears to be the most sustainable in terms of land-use efficiency, with ten megacities following this pathway. Overall, our results highlight the diverse mega -urban growth pathways across the world, particularly for megacities in the Global South which generally have higher growth rates.