Climate change will inﬂuence ecological systems across the planet, including expected range shifts in forest biomes. As the climate continues to warm, trailing edge forests have the potential to experience abrupt conversions to non-forest. Such conversions are of particular concern in the semi-arid and ﬁre-prone intermountain region of the western U.S. where many communities rely on forests for clean water, timber, and recreation. Yet, broad-scale conversions to non-forest are likely to be gradual in the absence of stand-replacing disturbances such as severe ﬁre. A USDA Forest Service study explicitly evaluated the spatial correspondence between trailing edge forest and stand-replacing ﬁre. It characterized areas that are primed for change and have the potential for ﬁre-facilitated conversion from forest to non-forest. The scientists found that 6.6 percent of current forest in the intermountain U.S. is at risk of such conversions, though this varied among ecoregions. Although this value (6.6 percent of forest) may not outwardly seem alarming, the scientists note that this is a conservative estimate. When they incorporated ﬁre severity predictions under extreme ﬁre weather in the southwestern United States, they found that 30 percent of forest is at risk of ﬁre-facilitated conversion to non-forest. Recent studies in the southwestern U.S. and elsewhere have documented such conversions. Given their estimate that nearly 36 percent of forest area in the intermountain U.S. will be trailing edge forest by mid-century, other non-ﬁre disturbances such as drought, insect outbreaks, and their interactions may put trailing edge forests at further risk.