Coastal ecosystems, found along the margins of the world's large water bodies, are regions of remarkable biological productivity, high accessibility and great importance to society. They have been centres of human activity for millennia, and in the last century are becoming increasingly populated. Recent assessments estimate that roughly 3.2 billion people, or more than half the current global population, are believed to live on or within 200 km of a coastline. By 2025 that number is expected to increase to 6.3 billion or 75 percent of the then global population (UNESCO, 2003b).

Why focus on coastal areas?
The integrated, cross-boundary coastal zone is comprised of terrestrial and aquatic ecosystems including: coral reefs, mangroves, tidal and non-tidal wetlands, sea grass beds, barrier islands, estuaries, peat swamps, lagoons, river reaches, deltas, coastally restricted forests, and sea and land ice. Each of these ecosystems, and their associated habitats and biota, provides its own distinct bundle of goods and services, and faces somewhat different pressures from human activity. These systems host the world's prime locations of human habitation, commerce and recreation; they provide agricultural products, fish, shellfish, and seaweed for both human and animal consumption, and they are a considerable source of fertilizer, pharmaceuticals, consumer products, and construction materials (Costanza et al., 1997; Cohen, et al., 1997; Jackson, Kurtz and Fisher, 2000; Scialabba, 1998).

Increasing urbanisation and alteration of coastal habitats contribute to changes in biodiversity, biogeochemical cycles, hydrological cycles, and ecology of the systems (Jackson, Kurtz and Fisher, 2000; Seitzinger and Kroeze, 1998; Vitousek et al., 1997). These pressures at local, regional and global levels, in combination with impacts from bordering marine and inland ecosystems (e.g. climate induced sea level rise and terrestrial pollutants), have profound environmental and socio-economic implications for the sustainability of coastal areas.

Early recognition of the importance of coastal ecosystems and monitoring was shown by the global community through the outcomes of two conferences: the Convention on Wetlands held in Ramsar, Iran, in 1971, and the UN Conference on the Human Environment in Stockholm, Sweden, in 1972. In 1992, the UN Conference on Environment and Development in Rio de Janeiro, Brazil, provided an international forum for the concept of sustainable development. Agenda 21 was one of the major resulting products. Chapter 17 of Agenda 21 contained provisions for the protection of oceans, seas, coastal areas, and related resources, providing the political instrument for the inclusion of the sustainable development concept into the management of coastal areas. Commitments to sustainable use of coastal areas have been made since the Rio convention through such global instruments as: the UN Convention on the Law of the Sea (UNCED), the Convention on Biological Diversity (CBD); the Barbados Action Plan; the Global Programme of Action (GPA) for the Protection of the Marine Environment from Land-Based Activities, and the FAO Code of Conduct for Responsible Fishery practices and associated action plans (Duda and Sherman, 2002). International organizations and nations alike responded to the new coastal resource management needs, including: the development and endorsement of guidelines for Integrated Coastal Area Management (ICAM) by UN agencies (Scialabba, 1998; UNESCO 2003c; UNEP, 2004); multi-national cooperation through such programmes as the Regional Seas Program (RSP) and the Large Marine Ecosystems projects (Sherman and Duda, 1999), together with scientific programmes researching social and environmental causal links for the degradation of coastal resources (GESAMP, 2001).
All of these political instruments, management, and research activities require global and regional resource assessments, as well as associated data collection infrastructure. Furthermore, recent environmental targets set by the Millennium Development Goals and the World Summit on Sustainability (WWSD) in 2002 emphasize the need for ongoing mechanisms for coastal monitoring and strengthening of Agenda 21 coastal initiatives.

Acquiring data on coastal zones
The coast presents a particular challenge to assessing global change. The discontinuity between the land and ocean provides complexities that challenge the efforts of global observing systems. A number of activities have commenced within the United Nations and other international organisations to address observation needs in coastal areas including new coastal programmes within the Integrated Global Observing System (C-IGOS), the Global Oceans Observing System (C-GOOS) and the Global Terrestrial Observing System (C-GTOS). The pages presented here within the TEMS Coastal module are part of the Coastal GTOS effort, and include coastal information on Variables, Data, Links, Glossary of terms, and Questions and Answers.

The Coastal module of TEMS and C-GTOS
The primary goal of C-GTOS is to detect, assess and predict global and large-scale regional change associated with land-based, wetland and freshwater ecosystems along coasts. GTOS will establish a regime for observing, assessing and predicting global and large-scale regional change for select ecological and associated socio-economic issues critical to coastal areas:

• population dimensions, land cover/land use and critical habitat alteration;
• sediment loss and delivery;
• water cycle/water quality;
• effects of sea level change, storms and flooding.