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The following HTML text is provided to enhance online readability. Many aspects of typography translate only awkwardly to HTML. Please use the page image as the authoritative form to ensure accuracy. Page 2 to provide a brief review of the strategy, scope, and quality of existing polar geophysical data sets and help NASA find ways to make these products and future polar data sets more useful to researchers, especially those working on the global change questions that lie at the heart of NASA's Earth Science Enterprise. THE POLAR REGIONS AND NASA'S EARTH SCIENCE ENTERPRISENASA's Earth Science Enterprise (ESE) is one of four strategic enterprises being used to guide the agency's overall research direction. The ESE is dedicated to understanding the total Earth system and the effects of humans on the global environment. Within this enterprise, NASA works with inter-agency and international partners to understand patterns in climate that, ultimately, should allow the nation to predict and respond more quickly to environmental events such as floods and severe winters (NASA, 2000). ESE priorities are driven by five key science questions: 1. How is the global Earth system changing? 2. What are the primary forcings of the Earth system? 3. How does the Earth respond to natural and human-induced changes? 4. What are the consequences of change in the Earth system for human civilization? 5. How well can we predict the changes in the Earth system that will occur in the future? These science questions drive current NASA research initiatives and thus help define the focus and scope of future data set needs. In this report, the committee looks at these key science-driving questions from a cryospheric perspective and describes the most important research issues and the measurements required to address those issues. Thus, the first ESE question, “How is the global Earth system changing?,” which addresses variability and trends in the climate and biosphere system, becomes “Are changes occurring in the polar atmosphere, ice sheets, oceans, and terrestrial regime?” and various sub-questions of relevance. The second question about primary forcing agents of the climate system becomes “What are the major fluxes of CO2 and other trace gases from the polar land surfaces and oceans?” and “What are the spatial and temporal distributions and variability of aerosols in the polar atmosphere?” The third question, focused on responses to change, breaks down into a number of important questions, such as “How will the atmospheric contribution to the mass balance of ice sheets change with the effects of
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