Understanding the science of climate change: Talking Points - Impacts to arid lands

Abstract

Arid ecosystems are particularly sensitive to climate change and climate variability because organisms in these regions live near their physiological limits for water and temperature stress. Slight changes in temperature or precipitation regimes, or in magnitude and frequency of extreme climatic events, can significantly alter the composition, abundance, and distribution of species. Observed climate changes in the southwestern U.S. include increased seasonal and annual average temperatures, increased minimum temperatures, and decreases in the length of the frost-free period and number of frost days. In general the region has become more arid over the past few decades, with a significant decrease in regional snowpack and a broad-scale shift in the timing of snowmelt runoff to earlier in the season. Projected climate changes include continued increases in temperature, potentially at rates faster than observed rates of change, and a large reduction in the volume and persistence of mountain snowpacks. Precipitation and flooding events are projected to become more extreme, even as drought conditions intensify. Observed and projected climate changes will likely alter plant species ranges; shift the geographic and elevational boundaries of the Great Basin, Mojave, Sonoran, and Chihuahuan deserts; cause major changes in vegetation composition and cover, increase rates of erosion and sediment transport to streams; result in increased tree mortality from synergistic associations between drought stress and insect outbreaks; increase the frequency, size, and duration of wildfires; and increase the probability of extinctions in plant and animal species.

Citation

Loehman, Rachel. 2010. Understanding the science of climate change: Talking Points - Impacts to arid lands. Natural Resource Report NPS/NRPC/NRR-2010/209. Fort Collins, CO: U.S. Department of the Interior, National Park Service, Natural Resource Program Center. 35 p.