As urbanization accelerates, World Heritage properties, critical conservation areas, face a growing threat of urban densification, jeopardizing their Outstanding Universal Value (OUV). States Parties, the countries that have ratified the World Heritage Convention, are responsible for submitting periodic reports on the state-of-conservation of their World Heritage properties. These reports should explicitly address any instances of urban densification that may be occurring. But do they? This research investigates the relationship between urban densification and reporting practices in World Heritage properties over time and space. Through a spatiotemporal analysis, by analyzing changes in the built-up area within the core zones of cultural World Heritage properties from 1985 to 2015. We found that urban development, including housing, infrastructure, and tourism facilities, has significantly impacted World Heritage properties and an increase in built-up area can be observed especially in properties not reporting on urban threats.@en

The quantification of the extent and dynamics of land-use changes is a key metric employed to assess the progress toward several Sustainable Development Goals (SDGs) that form part of the United Nations 2030 Sustainable Development Agenda. In terms of anthropogenic factors threatening the conservation of heritage properties, such a metric aids in the assessment of achievements toward heritage sustainability solving the problem of insufficient data availability. Therefore, in this study, 589 cultural World Heritage List (WHL) properties from 115 countries were analyzed, encompassing globally distributed and statistically significant samples of “monuments and groups of buildings” (73.2%), “sites” (19.3%), and “cultural landscapes” (7.5%). Land-cover changes in the WHL properties between 2015 and 2020 were automatically extracted from big data collections of high-resolution satellite imagery accessed via Google Earth Engine using intelligent remote sensing classification. Sustainability indexes (SIs) were estimated for the protection zones of each property, and the results were employed, for the first time, to assess the progress of each country toward SDG Target 11.4. Despite the apparent advances in SIs (10.4%), most countries either exhibited steady (20.0%) or declining (69.6%) SIs due to limited cultural investigations and enhanced negative anthropogenic disturbances. This study confirms that land-cover changes are among serious threats for heritage conservation, with heritage in some countries wherein the need to address this threat is most crucial, and the proposed spatiotemporal monitoring approach is recommended.

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