The American Geophysical Union recommends that the U.S. take the initiative amongst nations to establish an international observing system which, in conjunction with an active research program, will allow scientists to understand natural and anthropogenic changes in the Earth's environment and the global-scale forces that control them. Results from such a program will improve the assessment and prediction of natural disasters and climatic changes, may permit the prevention of some anthropogenic climatic changes, and will enhance the wise use of natural resources. Participation by all nations in both the space and ground-based activities of this Planet Earth Initiative (PEI) should be encouraged. Special attention should be given to eliciting the cooperation of the U.S.S.R. in the initiation of this program.