Earth information-the diagnostics of Earth's climate, water, air, land, and other dynamic processes-is essential for our understanding of humankind's relationship to our natural resources and our environment. Earth information can inform our scientific knowledge, our approach to resource and environmental management and regulation, and our stewardship of the planet for future generations. New data sources, new ancillary and complementary technologies in hardware and software, and ever-increasing modeling and analysis capabilities characterize the current and prospective states of Earth science and are a harbinger of its promise. A host of Earth science data products is enabling a revolution in our ability to understand climate and its anthropogenic and natural variations. Crucial to this relationship, however, is understanding and improving the integration of Earth science information in the activities that support decisions underlying national priorities, ranging from homeland security and public health to air quality and natural resource management. Also crucial is the role of Earth information in improving our understanding of the processes and effects of climate as it influences or is influenced by actions taken in response to national priorities. Global change observations, data, forecasts, and projections are integral to informing climate science. The Synthesis and Assessment Product (SAP), ''Uses and Limitations of Observations, Data, Forecasts, and Other Projections in Decision Support for Selected Sectors and Regions"(SAP 5.1), examines the current and prospective contributions of Earth science information in decision support activities and their relationship to climate change science. The SAP contains a characterization and catalog of observational capabilities in a selective set of decision support activities. It also contains a description of the challenges and promise of these capabilities and discusses the interaction between users and producers of information (including the role, measurement, and communication of uncertainty and confidence levels associated with decision support outcomes and their related climate implications)."