Charles F. Kennel, Pierre Morel, and Gregory J. Williams, in a 1997 article in Consequences magazine entitled "Keeping Watch on the Earth: an Integrated Global Observing Strategy," give an overview of the environmental problems demanding global data. They also describe the scientific challenges in the near term (seasonal-to-interannual climate prediction), the intermediate term (long-term climate changes), and the long term (ecosystem research). They discuss progress toward an integrated observing system and point out the impediments for establishing such a capability.
Current implementation of a global observing system consists of three parts. The Global Climate Observing System (GCOS) focuses on climate observations from satellites and in-situ measurements of the atmosphere, ocean, and land surface. The Global Ocean Observing System (GOOS) provides information on global oceans. The Global Terrestrial Observing System (GTOS) includes programs for monitoring coastal regions, ecosystems, glaciers, hydrology, mountainous environments, and permafrost.