Annual precipitation amounts are less than 10 inches at the mid and lower elevations, while areas above 8,000 feet receive over 20 inches of precipitation. The few and highly scattered mountains that reach elevations near or more than 11,000 feet elevation can receive nearly 3 feet of precipitation.
And, like precipitation, temperatures also vary considerably within the Colorado Plateau. In the southern and lower elevations, temperatures range from the low 20’s (degrees Fahrenheit) in the winter to the lower and mid 90’s in the summer. At mid and upper elevations, temperatures range from the low 60’s and 70’s in the summer, to the single digits and low teens in the winter.
Multi-decadal droughts cycles are linked to Pacific Decadal Oscillation (PDO), which is an index of sea surface temperatures in the northern Pacific.
Climate Change and the Colorado Plateau
Much research has been and is being done related to climate change in the Colorado Plateau and there are numerous sources of information on the subject. Recent climate change models applied to the Colorado Plateau predict significant changes in the next 30-100 years. Predictions include temperature increases of 3.0oC (5.4oF) by 2050 during May and June when drought stress is greatest, and by 4.5-5.0oC (8.1-9oF) by 2090. Winter temperatures are estimated to increase on the order of 2.5oC (4.2oF) by 2050 and 3.0oC (5.4oF) by 2090. Winter temperatures are likely to rise by similar amounts by 2050 and 4.0oC (7.2oF) by 2090.
By 2090, precipitation is predicted to decline by as much as 5 percent across the Colorado Plateau. This reduction, while apparently small, is critical when looking at the already low amounts of precipitation most of the region experiences. Any declines in precipitation are likely to increase drought stress in existing native plant communities resulting in a greater susceptibility of existing ecosystems to replacement by noxious and other invasive weedy species.
A Few Available Publications and Web Links on Climate History and Change
Millar, C.I. 2006. Climate Change; Confronting the Global Experiment. In: Proceedings of the Forest Vegetation Management Conference; Redding, CA January 2006. [online] URL: http://www.fs.fed.us/psw/publications/millar/pub_global_experiment.pdf