Digital Earth

The term digital earth was coined by then U.S. Senator Al Gore in his 1992 book, Earth in the Balance, 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 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 the Digital Earth project to the National Aeronautics and Space Administration (NASA), and several activities were initiated through collaboration between government, universities, and the private sector. International interest in the concept was strong, and a series of international symposia on Digital Earth have been held, beginning in Beijing in 1999.

Political interest in Digital Earth waned with outcome of the U.S. election of 2000, but activities continue that are aimed at a similar vision, often under other names such as “Virtual Earth” or “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,” all based on data obtained in real time over the Internet, is now available from several sources, of which the best known is Google Earth. Environmental Systems Research Institute (ESRI) will shortly offer ArcGIS Explorer, while NASA has its own public domain contribution called Worldwind. All of these require the user to download free client software. Google Earth has popularized the concept of a “mashup,” by allowing users to combine data from other sources, including their own, with the service's basic visualizations. Readily accessible mashups include dynamic, three-dimensional, and real-time data.

The vision of Digital Earth proposes that a complete digital replica of the planet can be created—a “mirror world.” Such a replica would be of immense value in science, since it would enable experiments to investigate the impacts of proposed human activities (such as the large-scale burning of hydrocarbons or 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 Gore dream of Digital Earth can be realized. Meanwhile, the technology currently appears limited to virtual exploration of the planet's current and possibly past physical appearance.