In order for CCSP research outputs/findings (including, but not limited to the SAPs) to be both scientifically accurate and useful to decision makers, scientific uncertainties must be acknowledged and clearly defined. Given the importance of providing clear information concerning uncertainties associated with the application of climate science and information in decision making, the CCSP is developing a Synthesis and Assessment Product (5.2) that explicitly focuses on best practices for characterizing, communicating and incorporating scientific uncertainty. This prospectus outlines the plans for the development of SAP 5.2.

Topic and Content

Uncertainty factors into large and small decisions made by individuals every day throughout society. The choice to bring an umbrella to work, take a new job, or to move to a new neighborhood all involve some degree of uncertainty, with various levels of risk and opportunity that must also be considered. In most cases, the uncertainties inherent in personal decisions are not treated as explicitly and systematically as they might be. Unlike personal decision-making, building an understanding of potential climate change impacts requires a synthesis of science, practical resource management strategies and an anticipation of the requirements for the long-term health and welfare of human society and the environment. This complex analysis creates a demand and opportunity for examining the way scientific uncertainty is articulated, communicated, and considered in decision making.

The Strategic Plan for the U.S. Climate Change Science Program defines uncertainty as:

An expression of the degree to which a value (e.g., the future state of the climate system) is unknown.

Uncertainty concerning the nature and impacts of climate change and variability is the inevitable consequence of the necessary synthesis of various types of data of varying degrees of quality with models possessing varying degrees of skill in simulating natural processes and human behavior. Scientists work to minimize uncertainty in their projections by identifying its nature and source and, then by undertaking focused research to reduce the margin between what is known and what is not known. Various factors can complicate the accurate formulation and communication of uncertainty in climate change projections including the definition of concepts, terminology, and scale (Moss and Schneider, 2000).

The level of certainty in the projections of climate change and its effects has emerged as a central issue in the public discourse, reinforcing the need to evaluate current methods and to define best practices for assessing uncertainty. The scientific community – which includes scientists from academia, government, and the private sector, as well as research and operational entities2 - are looked to by policymakers, decision makers, and the media for “answers” (or insights) about trends, rates, impacts, and adaptation options related to climate change. Meeting these societal demands, and providing effective support for decisions in sectors and regions affected by climate change and variability, requires a better understanding and articulation of the nature and


In the context of this discussion, operational entities are those which regularly provide science-based products for utilization by other technical entities and the general public.

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