Risk ratios for three measures of extreme wildfire risk in the Southern Prairies Homogeneous Fire Regime zone (Boulanger et al., 2014), showing the increase in likelihood due to the anthropogenic contribution. A risk ratio greater than 1 (dashed line) indicates the extreme event is more likely when the human contribution is included. The three measures used to characterize extreme wildfire risk in this region are fire weather (extreme Fire Weather Index), fire behaviour (high number of fire spread days), and fire season (long fire seasons). The error bars represent the 5–95% uncertainty range.
Adapted from Kirchmeier-Young et al., 2017a.