Coastal Populations and Topology

This map shows the level of human modification of the coastal zone, by examining the population within 100 kilometres from the coast. As human population increases in coastal areas, so does pressure on coastal ecosystems through habitat conversion, increased pollution, and demand for coastal resources. The degree of direct human modification of coastal ecosystems can be inferred by looking at the population density within the coastal zone. Globally, the number of people living within 100 km of the coast increased from roughly 2 billion in 1990 to 2.2 billion in 1995-39 percent of the world's population.

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Analytical Overview

This analysis was conducted using a new spatially explicit database reflecting global human population developed for PAGE. The database was developed based on population censuses from various countries and the estimates were standardized for the year 1995. If the map showing Natural versus Altered Landcover within 100 km of a Coastline is compared with this one, one can observe that high population density correlates with urban areas which is classified in the former as 'altered' lands. The most uninhabited areas, as is expected, are in northern latitudes, where much of the 'natural' land cover remains.

Sources:

1. Center for International Earth Science Information Network (CIESIN); Columbia University; International Food Policy and Research Institute; and World Resources Institute. 2000, Gridded Population of the World, Version
2. Palisades, NY: CIESIN, Columbia University.

Here, the general distribution of natural characteristics in tidal and near-shore areas is illustrated. The characterization of the world's shoreline is based upon the occurrence of habitat types, such as coral reefs, mangroves, other tidal wetlands, barrier islands, estuaries, and sea ice. It also integrates information on continental shelf width and the slope of nearby terrestrial areas. As shown in Map 1, the world's coastlines are quite diverse in terms of physiographical characteristics. A mountainous, narrow shelf and some estuarine systems dominate the Mediterranean coastline, coral reefs and mangroves are predominant in the Middle East and Insular Southeast Asia, while East Africa has a varied coastline with coral reefs, mangroves, and coastal plains along a narrow shelf.

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Analytical Overview

The analysis was implemented at 1-kilometer resolution using multiple data layers showing distribution of various coastal habitat types. A hierarchical classification scheme was used to simplify the classification of complex ecosystems and overlapping habitat types. The generalized categories include sea ice, wetlands/estuaries/deltas, barrier islands and BI systems (where some habitat types may overlap), mangroves/coral reefs, hilly narrow shelf, narrow and wide shelf plains, hilly wide shelf, and mountainous narrow shelf. The hierarchy was determined based on both the quality of the data sets and the importance of these habitats for the ecosystem goods and services. This characterization is admittedly a gross simplification of the highly varied coastal environments of the world and it does not directly address climate, currents, or substrate. More complex or detailed characterizations are possible and should be explored at national or regional scales.

Sources:

1. UNEP-WCMC (United Nations Environment Programme - World Conservation Monitoring Centre). 1998, Global Wetland Distribution. Cambridge, UK: UNEP-WCMC.
2. UNEP-WCMC (United Nations Environment Programme - World Conservation Monitoring Centre). 1999, Global Mangrove Distribution. Cambridge, UK: UNEP-WCMC.
3. Environmental Systems Research Institute. 1992, ArcWorld 1:3M. Continental Coverage. Redlands, CA: ESRI.
4. Environmental Systems Research Institute. 1993, Digital Chart of the World CD-ROM.
5. IOC (Intergovernmental Oceanographic Commission), IHO (International Hydrographic Organization), and BODC (British Oceanographic Data Centre). 1997, General Bathymetric Chart of the Oceans (GEBCO) 97: The 1997 Edition of the GEBCO Digital Atlas. Birkenhead, UK: British Oceanographic Data Centre.
6. NSIDC (National Snow and Ice Data Center). 1999, DMSP SSM/I Brightness Temperatures and Sea Ice Concentration Grids for the Polar Regions, 1987-1998. Boulder, CO: NSIDC Distributed Active Archive Center, University of Colorado at Boulder.
7. LOICZ (Land-Ocean Interactions in the Coastal Zone). 1998, Coastal Typology Dataset. Texel, The Netherlands: International Project Office, International Geosphere-Biosphere Programme.
8. Stutz, M.L.. 1999, Distribution of Barrier Islands.
9. UNEP-WCMC (United Nations Environment Programme - World Conservation Monitoring Centre). 1999, Global Coral Reef Distribution. Cambridge, UK: UNEP-WCMC.
10. Stutz, M.L., A.C. Trembanis, and O.H. Pilkey. 1999. 'Barrier Island Morphology on the U.S., Canadian, and Russian Arctic Coasts'. EOS Transactions AGU 80(46):