An anatomy of adaptation to climate change and variability

Adaptation to climate variability and change is important both for impact a ssessment (to estimate adaptations which are likely to occur) and for polic y development (to advise on or prescribe adaptations). This paper proposes an "anatomy of adaptation" to systematically specify and differentiate adap tations, based upon three questions: (i) adapt to what? (ii) who or what ad apts? and (iii) how does adaptation occur? Climatic stimuli include changes in long-term mean conditions and variability about means, both current and future, and including extremes. Adaptation depends fundamentally on the ch aracteristics of the system of interest, including its sensitivities and vu lnerabilities. The nature of adaptation processes and forms can be distingu ished by numerous attributes including timing, purposefulness, and effect. The paper notes the contribution of conceptual and numerical models and emp irical studies to the understanding of adaptation, and outlines approaches to the normative evaluation of adaptation measures and strategies.