Name: Seth Westra

Title: Implications of Bottom-Up Framing for Climate Impact Assessments

Abstract: There has been considerable recent interest in ‘bottom-up’ (or ‘scenario neutral’) framings of the climate impact assessment process, which places primacy on system values (and/or performance metrics and thresholds), stress testing and identification of alternative options. Applications of this framing have shown that: (1) there is rarely a single clearly defined and agreed upon ‘system’, with different stakeholders emphasising different values and in turn providing alternate system delineations, and moreover (2) system delineations invariably span multiple spatial and temporal scales and consider multiple atmospheric variables, meaning that (3) almost all climate stressors are ‘compound’, and that (4) most systems are vulnerable to combinations of extreme and non-extreme climatic (and indeed also non-climatic forcings). Implications for extreme value statistical methods are then discussed, arguing that a flexible and accessible ‘library’ of methods urgently needed to minimise transaction costs for integrating extreme value theory into bottom-up assessments.