Understanding and responding to the impacts of climate variability and change on water and environmental systems requires analysis, modeling methodologies, and tools that accommodate incomplete knowledge and uncertainty that themselves evolve over time. The broad scope of this problem necessitates a multidimensional dialogue among research and policy groups that span disciplinary boundaries. Integration of this knowledge is required to develop adaptive capacity (i.e., necessary knowledge, preparedness, and reliable decision-making capacity to act by all partners in the information chain) and resilience. In this context, resilience can be taken to mean the degree to which the environmental system can absorb both abrupt and gradual changes and build capacity for learning and adaptation.