Data Sources and Methods for the Global Trends in Protected Areas Indicator
The World Database on Protected Areas (WDPA) is held within a geographic information system (GIS) that stores information about protected areas, including their name, type, date of designation, and documented area, as well as their geographic location as a point and/or boundary.
Quality control criteria are applied to ensure consistency and comparability of the data in the WDPA. New data are validated at the United Nations Environment Programme (UNEP) World Conservation Monitoring Centre (WCMC) in coordination with the World Commission on Protected Areas and the data provider as well as local experts. Discrepancies between the data in the WDPA and new data are resolved in communication with data providers. Processed and validated data are fully integrated into the published WDPA once it has been approved by the data provider and formal permission has been obtained through a data contributor agreement.
Values reported here are based on a Millennium Development Goals Analysis completed by the WDPA; raw values from that analysis have been used to provide totals and percentages for areas as described below.
Methodology is provided by the WDPA; only the sections relevant to this indicator are included here. The area protected includes all areas recorded in the WDPA whose location and extent were known, with the exception of Man and the Biosphere Reserves, areas in the high seas, disputed territory, and areas in the Great Lakes, Caspian Sea and Aral Sea.
A spatial analysis was used to estimate total territorial area protected. If the boundaries of a protected area were not known, but its location and extent were known, it was modelled as a circular buffer around its point location. A global protected area layer was created by combining the boundaries (polygons) of the protected areas recorded in the WDPA. To estimate the area protected in 1990, a layer was created by combining only those polygons with an establishment date of 1990 or earlier (including any with an unknown establishment date). This was repeated for 2000, 2010 and 2012.
The protected area layers were intersected with country boundaries, including coastlines and marine boundaries to obtain the absolute coverage (in square kilometers) of protected areas by country, divided into marine and terrestrial. The total terrestrial protected area of a country or territory was divided by the total area of its land (including inland waters) to obtain the relative coverage (percentage) of protected area. The total marine protected area of a country was calculated by adding all of the protected marine area and then dividing it by the total national marine area to exclusive economic zones (EEZ) limits in order to obtain the relative coverage of marine protected area.
Global terrestrial and marine totals were obtained from the protected areas layers for 1990, 2000, 2010 and 2012. The global terrestrial total was divided by the global terrestrial area (total national area plus the area of Antarctica, disputed territories, Great Lakes, Caspian Sea and Aral Sea) to obtain the relative coverage (percentage) of protected area. Similarly, the global marine total was divided by the marine area, including territorial seas, exclusive economic zones, and the high seas. Increases in area protected were calculated by dividing the difference in area (later year minus earlier year) by the total area protected in the earlier year.
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