On the Nexus of the Spatial Dynamics of Global Urbanization and the Age of the City

Abstract

A number of concepts exist regarding how urbanization can be described as a process. Understanding this process that affects billions of people and its future development in a spatial manner is imperative to address related issues such as human quality of life. In the focus of spatially explicit studies on urbanization is typically a city, a particular urban region, an agglomeration. However, gaps remain in spatially explicit global models. This paper addresses that issue by examining the spatial dynamics of urban areas over time, for a full coverage of the world. The presented model identifies past, present and potential future hotspots of urbanization as a function of an urban area's spatial variation and age, whose relation could be depicted both as a proxy and as a path of urban development.

Unravelling the Frontiers of Urban Growth: Spatio-Temporal Dynamics of Land-Use Change and Urban Expansion in Greater Accra Metropolitan Area, Ghana

“…For the purposes of quantifying rate, intensity, and patterns of urban expansion, the images for the two years were further re-classified into two discrete land-use classes: "urban built-up land" and "non-built-up land". Urban built-up land consists of areas of intensive use covered by settlements, including cities, towns, villages 4 , etc., as well as physical structures such as roads/highways, buildings (for residential, commercial, institutional and industrial purposes), and other built-up plots of lands. The non-built-up land comprises agricultural/farmlands, grasslands, open-space/bare-land, forests, and wetland/waterbodies.…”

“…These included: Average Annual Urban Expansion Rate (AUER) [36], Urban Growth Coefficient (UGC), Expansion Intensity Index (UEII) [47], and Urban Expansion Differentiation Index (UEDI) [48]. 4 In the context of GAMA and Ghana as a whole, urban centers are officially defined as settlements with populations of 5000 or more. Below the urban centers are settlements considered "rural" or "village" with populations less than 5000.…”

“…Urbanization 1 -driven land-use change has emerged as a pervasive megatrend and component of environmental change, courting rigorous scientific enquiry both on local and global scales [1]. Current processes and spatial patterns of urban expansion strongly induce the conversion of natural landscape to urban/built-up area, thereby causing rapid changes in land use [2][3][4]. As urban populations continue to grow as projected to exceed 60% by 2030 [5], urban areas will remain in a dynamic state of expansion and, as such, relentless changes in land use will intensify in ways that require constant investigation [6].…”

Grand Challenges: Forests and Global Change

“…Globally, economic development is bringing continued and even accelerating urbanization, accompanied by declining rural populations (Figure 2; United Nations, 2014). Unarguably, the Anthropocene is also "the age of the city" (sensu Scheuer et al, 2016), with 4 billion people living in metropolitan areas in 2014, and as many as 6.5 billion will do so by 2050. The extraordinary change in "where people live, " has followed rapid improvements in efficiency of primary production, such that far fewer people are now required per unit production in well-developed countries.…”

“…So profound is the urbanization effect that the "concept, vision, values and utility of forests and the countryside today are largely defined by people living and working in cities" (Westin et al, 2017). It is not surprising that regions with greatest rates of net loss of forest are those that also have the fastest rates of urbanization (Scheuer et al, 2016).…”