Metrics: moving beyond the adaptation information gap — introduction to the special issue

This introduction to the special issue addresses the need to move beyond the adaptation information gap and the benefits and problems inherent in this move. It provides a background on this project and a brief review of the existing literature and recent advances in developing measurement and assessment instruments — ‘metrics’ — for the important guiding concepts of water security and adaptive capacity in water management. The review summarizes the promise and challenges encountered in the development and application of metrics and demonstrates that significant challenges remain in developing and applying metric instruments in real-world contexts, the most vexing being the lack of agreement on what model(s) to use and how to weight factors; the lack of evaluation of the validity and robustness of the instruments; the lack of consistency in analytical and application scales; deficits in engaging public participation in instrument design and use; and enduring tensions between contextualized and systematized knowledge, descriptive and predictive capabilities, and static and fluid data.