Multi-Scale Estimation of Land Use Efficiency (SDG 11.3.1) across 25 Years Using Global Open and Free Data

Abstract

Sustainable Development Goal (SDG) 11 aspires to “Make cities and human settlements inclusive, safe, resilient and sustainable”, and the introduction of an explicit urban goal testifies to the importance of urbanisation. The understanding of the process of urbanisation and the capacity to monitor the SDGs require a wealth of open, reliable, locally yet globally comparable data, and a fully-fledged data revolution. In this framework, the European Commission–Joint Research Centre has developed a suite of (open and free) data and tools named Global Human Settlement Layer (GHSL) which maps the human presence on Earth (built-up areas, population distribution and settlement typologies) between 1975 and 2015. The GHSL supplies information on the progressive expansion of built-up areas on Earth and population dynamics in human settlements, with both sources of information serving as baseline data to quantify land use efficiency (LUE), listed as a Tier II indicator for SDG 11 (11.3.1). In this paper, we present the profile of the LUE across several territorial scales between 1990 and 2015, highlighting diverse development trajectories and the land take efficiency of different human settlements. Our results show that (i) the GHSL framework allows us to estimate LUE for the entire planet at several territorial scales, opening the opportunity of lifting the LUE indicator from its Tier II classification; (ii) the current formulation of the LUE is substantially subject to path dependency; and (iii) it requires additional spatially-explicit metrics for its interpretation. We propose the Achieved Population Density in Expansion Areas and the Marginal Land Consumption per New Inhabitant metrics for this purpose. The study is planetary and multi-temporal in coverage, demonstrating the value of well-designed, open and free, fine-scale geospatial information on human settlements in supporting policy and monitoring progress made towards meeting the SDGs.

Land Consumption and Land Take: Enhancing Conceptual Clarity for Evaluating Spatial Governance in the EU Context

“…Over the past decade, a growing number of studies have addressed the operationalization of the concepts of land consumption and land take and related analytical questions [16,19,20,22,39]. This increased interest has been spurred by the fact that both concepts are components of internationally agreed sustainability indicators and are thus of high political relevance.…”

“…As mentioned in the introduction, the SDG indicator 11.3.1 is composed of the quotient of the land consumption rate (LCR) and the population growth rate (also referred to as the land use efficiency [16,46]). LCR is defined as "the percentage of current total urban land that was newly developed" [11] and calculated as (ibid.…”

“…The methodology for computing the land consumption rate for the SDG indicator 11.3.1 is subject to a scientific debate [22]. Promising advances have been made in using new global datasets, tools, and maps, specifically those subsumed under the header "Global Human Settlement Layer, GHSL" [2,16,29,46]. However, there is no consensus yet on how to define the exact geographic boundaries of urban land and this poses a major challenge for assessing LCR [22,47].…”

“…Respective indicators and monitoring tools need to be available and they are expected to deliver reliable and comparable data. As mentioned above, both concepts, land consumption and land take, are used in international reporting systems, but several methodological issues are still under debate [16,19,22,29]. In this context, it is critical to acknowledge that there is a great variety in land cover classification systems worldwide [62], and to specify which system has been applied in the case at hand.…”

“…Built-up areas have expanded predominantly at the expense of agricultural land with mostly high-quality soils [1,14] and, during the past decades, expansion has not corresponded with urban population dynamics [15] (p. 11). In fact, between 1990-2015, Europe was the world region with the least efficient use of urban land: while the population increased in these years by 2.4%, the built-up areas expanded by more than 30% [16]. Acknowledging that this trend is unsustainable and that it risks fostering inexpedient urban sprawl with all its negative side-effects, the EU introduced the soil sealing guidelines [13] and declared the goal of "no net land take" within the EU by 2050 [17,18].…”