Title: Climate Change in the Southwest - Potential Impacts (U.S. National Park Service)
Headings: Climate Change in the Southwest - Potential Impacts
Series: Climate Change in the Southwest
Climate Change in the Southwest - Potential Impacts
Climate change in the Southwest
Potential climate change impacts
Water
Vegetation
Vegetation shifts
Fire
Impacts by Region

Content: In southern California, this shift is already happening. Between 1977 and 2007, dominant plant species in the Santa Rosa Mountains shifted upwards in elevation by about 65 m (Kelly and Goulden 2008). Warming may also affect the distribution of desert plants because of their sensitivity to freezing. Since the lower boundary of the Sonoran desert may be where freezes never happen and the upper boundary may be where freezes last less than 24 hours, warming temperatures would allow thorny shrubs and scrub trees from further south to establish in the current boundaries of the Sonoran desert, and the Sonoran desert would expand northward, eastward, and upward in elevation (Weiss and Overpeck 2005). From 1960 to 2000, the number of days below freezing has already decreased (Weiss and Overpeck 2005). Modeled future distribution of four plant species in the years 2000, 2030, 2060, and 2090 (left to right). While Gambel oak would increase if unmitigated climate change continues, the area occupied by pinyon pine and Utah juniper would decrease dramatically. Saguaro cactus would shift northwward. (from Rehfeldt et al. 2006)
Over a larger scale, these subtle impacts to plant communities may cause extensive changes, both to the distribution of