Digital Earth

The term Digital Earth was coined by then–U.S. Senator Al Gore in his book Earth in the Balance, published in 1992, to describe a future technology that would allow anyone to access digital information about the state of the earth through a single portal. The concept was fleshed out in a speech written for the opening of the California Science Center in early 1998, when Gore was vice president. By then, the Internet and Web had become spectacularly popular, and Gore sketched a vision of a future in which a child would be able to don a head-mounted device and enter a virtual environment that would offer a “magic carpet ride” over the earth's surface, zooming to sufficient resolution to see trees, buildings, and cars, and would be able to visualize past landscapes and predicted futures, all based on access to data distributed over the Internet. The Clinton administration assigned responsibility for coordinating the development of Digital Earth to the National Aeronautics and Space Administration (NASA), and several activities were initiated through collaboration among the government, universities, and the private sector (http://www.digitalearth.gov). International interest in the concept was strong, and a series of international symposia on Digital Earth have been held, beginning in Beijing, China, in 1999.

Political interest in Digital Earth waned with the outcome of the U.S. presidential election of 2000, but activities continue aimed at a similar vision, often under other names such as Virtual Earth and Digital Planet. The technical ability to generate global views, to zoom from resolutions of tens of kilometers to meters, and to simulate magic carpet rides is now available from several sources. Environmental Systems Research Institute (ESRI), the market leader in geographic information systems (GIS) software, now offers ArcGlobe as part of its ArcGIS package together with data sets at 30-m resolution. A Web-based visualization, developed by Keyhole, Inc. (purchased by Google in 2004), is available at http://www.earthviewer.com. NASA offers World Wind, its own public domain analog of Earthviewer (http://learn.arc.nasa.gov/worldwind/).

The vision of Digital Earth proposes that a complete digital replica of the planet—a mirror world—can be created. Such a replica would be of immense value in science because it would enable experiments to investigate the impacts of proposed human activities (e.g., the large-scale burning of hydrocarbons, the destruction of forests). This would require integration of data with models of process, something that is not yet part of any of the Digital Earth prototypes. Much research is needed on the characterization of processes before the full dream of Digital Earth can be realized. Meanwhile, the technology appears to be limited to virtual exploration of the planet's current and past physical appearance. Inevitably, there will be an emphasis on those aspects of the earth that are characterized by widely available data sets and that can be easily rendered in visual form. Thus, Digital Earth seems bound to privilege relatively static physical aspects of geography over dynamic social aspects.