Recently, a colleague (Brad Udall, University of Colorado) and I wrote a short overview of climate change in the West—based on peer-reviewed literature—that appeared in the journal Science (Overpeck and Udall, 2010). The big story is really in the Southwest. What follows here is a summary of our findings. (read more)
In the West, as much as 70 percent of the region’s precipitation falls during winter. Arizona and New Mexico are critically dependant on this winter precipitation. The region’s two main water lifelines, the Colorado River and the Rio Grande, tap the winter snows in the Rocky Mountains for approximately 70 percent of their annual water flow. (Read more)
In the Southwest, the most widespread example of species redistribution is the movement of woody plants like creosote bushes and mesquite trees into native grasslands. The spread of invasive species is also considered a form of species redistribution. These changes occur due to long-term environmental changes like climate change, short-term environmental disturbances like drought or fire, or human-induced land use changes like ranching. Research indicates species ranges are shifting on global and regional levels, towards the poles and upwards in elevation. (Learn more)
For five consecutive years, drought in the Upper Colorado River Basin limited the water flow into Lake Powell to no more than 62 percent of the historical average. In 2004, the mammoth reservoir was only one-third full. This precipitous decline in water storage highlighted the vulnerability of the resource to the confluence of climate and societal demand.
Current observations suggest that climate change is altering streamflows in ways that negatively impact water supply for southwestern populations. Many climate models suggest that these changes will worsen as the climate warms, accentuating the natural variability inherent in river flows.
Since water is one of the most vital resources in the arid Southwest, the consequences of reduced streamflows and changes in the timing of peak river flows will impact water consumption, agriculture production, economic growth, recreation opportunities, and electricity generation, among other vital services. (Find out more)
In the Southwest, climate is an important natural resource and a draw for tourists. Many people come to the region to take advantage of its warm, mild winters, to boat or kayak in the lakes and rivers, or to enjoy snow sports in the higher elevations.
Drought deeply affects the land, water, and people of the Southwest. It occurs when precipitation averages fall below the norm. A drought can persist for many years, punctuated by particularly severe dry stretches and sometimes a relatively rainy year. The cloudless skies associated with drought not only imply below-average rainfall, but also an increase in the amount of direct sunlight hitting the ground, which leads to higher evaporation rates.