Analyzing impact cascades: an integrative approach for assessing the interconnected effects of extreme events across sectors and systems

In today’s interconnected world, assessing the risks of extreme events has become increasingly complex. These events often trigger far-reaching consequences that spread throughout various sectors and systems due to complex interactions, resulting in compound and cascading impacts. While qualitative and quantitative approaches are commonly used separately in systemic impact research, we argue that methodological pluralism is necessary to address the complexity of these social-ecological systems. In this talk, we propose an integrative methodological approach for studying impact cascades and exemplify it via two case-study applications. The first focuses on using dimensionality reduction and pattern-mining techniques to assess spatiotemporal patterns in the occurrence of drought impacts in Germany. We explore how these patterns differ during multi-year drought events in contrast to short-lived droughts. Second, we leverage qualitative cognitive maps derived from 25 stakeholder interviews to investigate how drought impacts propagate in a case study in Thuringia, Germany. By using graph theory, we identify influential variables and show how pooling the knowledge of diverse stakeholder crowds can create new, emergent knowledge. We find that combining different methods helps revealing various facets of impact cascades and helps compensating for the limitations of individual methods. This can strengthen the research confidence as results that agree across different methods are less likely to be artefacts.