Limber pine (Pinus flexilis) is the dominant conifer of the subalpine zone in mountain ranges of the U.S. Great Basin. Models predict that high-elevation species will progressively migrate upslope with anthropogenically warming climates, and that populations will go extinct as they run out of habitat at mountain summits. Forest Service scientists studied seedling regeneration in limber pine in four mountain ranges of the western Great Basin and found that over the past 130 years, limber pine has regenerated upslope across upper treeline in a very limited number of locations. As importantly, seedlings are also regenerating below lower treeline, as well as across forest borders at middle elevations into former shrublands and meadows. Further, rather than the predicted continuous shifts responding to warming climates of the past century, seedling regeneration between 1883 and 2013 at all locations occurred in only one time interval: 1963-2000. This corresponded to a period of warm winters, cool summers, wet springs, and mild, wet autumns. In that successful tree regeneration requires about 10 years from seed-cone initiation to seedling establishment, migration of limber pine at least responds more complexly to climate than just a simple response to warming temperature. These complex conditions were met in the late 20th century in low, north ravines, mid-elevation meadows and shrublands where cold air pooled, and in a few locations above current upper treeline. The results suggest that limber pine has more resilience to warming temperatures than anticipated. ?