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significant challenges. Effective environmental management on a global scale raises 
substantial issues of technology, policy, and economics [Raney and Specter, 1989]. This 
paper is concerned with the pivotal role of remote sensing data policy. It is our contention 
that remotely sensed information will have little impact on environmental management at 
the global scale without a change in the current data policy, or in the way that the cost of 
such data is underwritten by appropriate international agreements. 
Passive and Active Environmental Monitoring 
The first step is to recognize two legitimate roles of environmental monitoring: 
observation (passive monitoring); and intervention (active monitoring). Perhaps the largest 
and best known example of the first type is the Earth Observing System (EOS) of NASA 
[NASA, 1984], a $30 billion dollar effort to provide and interpret data from a variety of 
remote Earth sensors intended to start operation after launch in 1997. The objective of 
EOS is to observe, catalogue, analyze, and eventually to understand the environmental 
systems of the Earth. It is a legitimate scientific exercise of observation. 
The second role of environmental monitoring is to inform and assess regional and 
global efforts aimed at intervention on environmentally sensitive issues. One example of 
this type of active environmental monitoring [INPE, 1990] is the use of radar (RADAM- 
Brazil), AVHRR, and Landsat-TM by the Brazilian Institute for Space Research (INPE). 
The remotely sensed data was used to motivate and implement the national initiative "Our 
Nature", a program designed to shape national preservation policies for the country’s natural 
resources. It is intended to provide ongoing observations for the purpose of actively 
monitoring changes in Amazonia, and for guiding intervention and preservation programs. 
Technology and Data Policy 
Although active intervention on global environmental issues is not yet uniformly 
accepted as a necessity, there is a growing consensus in that direction. For effective 
environmental management to become a reality, active environmental monitoring will have 
to be widely adopted [World Commission on Environment and Development, 1987]. This 
requires that supporting systems and infra-structures be in place. There are two classes of 
issues to be satisfied before meaningful global environmental monitoring can be 
implemented: those of technology (data transformation); and those of policy (data 
availability). 
Interpretation of remote sensing data, and the development of techniques suitable 
for handling the large volumes of data required for global monitoring, have progressed 
substantially during the past decade. We argue that such progress will continue, and that 
by the end of the decade there will be no substantial technical barriers against the use of 
remote sensing data for active environmental monitoring. Technology is not seen as the 
pacing development.