Future global debris flow susceptibility considering climate change, wildfire probability, and glacier retreat

University of Torino, Earth Sciences Department, 10123 Torino, Italy

^* Corresponding author: Laurie.Kurilla@edu.unito.it

Abstract

The present-day impact of climate changes on debris flow magnitude, frequency, and susceptibility has been demonstrated in North and South America, Europe, Asia, and New Zealand. Such impacts are expected to increase under future emission scenarios. Future global debris flow susceptibility models provide an international perspective on areas worthy of further, more detailed analyses with regard to geographic changes in global debris flow susceptibility. In this study, future global debris flow susceptibility models are developed under RCP 2.6 and 8.5 IPCC Climate Change Scenarios. These models were further augmented with wildfire probability, and areas of potential glacier retreat, both of which can act as amplifiers to debris flow susceptibility. The results are projected against future urban centers, for a spatial view on potential human vulnerability. Key findings are (1) wildfire acts as a significant amplifier in area and magnitude of debris flow susceptibility in all modeling scenarios, (2) greater than 50% of the studied glaciers reside within higher susceptibility zones when wildfire is not considered, and greater than 75% when wildfire probability is considered, (3) 76 of the studied glaciers are within 5 km of eleven urban centers, (4) 11% of these “urban” glaciers are in higher susceptibility zones when wildfire probability is not considered, and 51% are in higher susceptibility zones when wildfire is considered, (5) about 12% of future urban centers will reside within higher susceptibility zones under both future climate change scenarios. Consideration of these factors, together with traditional environmental factors and triggers, and findings by local and regional glacier-related debris flow researchers, suggests a new paradigm in modeling debris flow susceptibility, at any scale.