Increasing daily wildfire risk in the Acadian Forest Region of Nova Scotia, Canada, under future climate change

Abstract

A conceptual system dynamic model of the impact of future climate change on fire risk in the Nova Scotian Acadian Forest Region (NS AFR) was developed, clarifying the influence of positive and negative drivers of future fire risk. Weights of relative importance for seven wildfire risk drivers identified in the conceptual model were elicited through an analytical hierarchy process. Expert participants identified precipitation, temperature, and local tree species composition as the most important determinants of future fire risk. Fire weather variables collectively received a weight of relative importance of ~0.7/1. Downscaled projected climate normals of the IPCC 2.6, 4.5, and 8.5 relative concentration pathways (RCPs) were used to model daily fire weather indices of the Canadian Forest Fire Weather Index System during the fire season in the NS AFR. Daily temperature during the modelled fire season increased significantly over time, as represented by climate normals periods. No significant increase or decrease in precipitation levels was identified. Indices of fuel moisture, fire behaviour, and potential fire intensity showed significant positive trends of drying and escalation of potential severity and intensity over time under all three RCPs (p < 0.05). Though significant, increases in potential fire weather intensity were moderate overall. Given the relative importance of fire weather as a driver of fire risk, and projected increasing potential for ignition and intensity of fire, we identify a moderate potential increase in fire risk in the NS AFR under climate change.