lead to the development of information that is capable of supporting high-quality decisions.

This chapter focuses on information needs for decision support, seen from the perspectives of decision makers. It emphasizes the need for research for decision support—that is, research that provides various types of decision-relevant information not currently provided by U.S. climate science programs—and basic and applied research on decision support. It highlights challenges associated with providing use-relevant data across spatial and temporal scales and across sectors, along with ways of overcoming those challenges. Short case studies are used throughout to illustrate information needs and approaches that are successfully engaging decision makers at local and regional scales.

Individuals and organizations facing climate-sensitive decisions are not often concerned with climate change per se, but rather with how it may affect their responsibilities, commitments, and priorities. Thus, information for climate-related decision support must be salient to their priorities, or it is unlikely to be helpful.

It follows that decision support strategies should be built on an understanding of decision makers’ values and priorities, as well as the constraints under which they operate. As highlighted in Chapter 2, this type of understanding is best developed through interaction between the decision makers and those who would inform them. Users’ needs are diverse and their data and information requirements are similarly diverse. In particular, they need information matched to the spatial and temporal scales of their agencies or organizations and concerning climate parameters that are meaningful to them; for an example, see Box 4-1.

The types of information required for climate responses are many and varied, ranging from climate data to data on affected populations and ecosystems. Agencies and organizations that are responsible for responding to extreme climate events need to know what types of events to prepare for and the likely occurrence of such events as well as the potential effects on human populations, economic activity, and built and natural systems. Understanding these effects in turn requires knowledge about population characteristics, current and future settlement patterns, social vulnerability, trends within national, regional, and local economies, and ecological variables.

Information is required for a wide range of potential mitigation and adaptation strategies. Mitigation decisions may center on ways of reducing greenhouse gas emissions, decreasing atmospheric greenhouse gas concentrations, and changing land cover. On the adaptation side, decisions focus