snow

More dust lying atop the CO snowpack may be leading to faster melting, causing woes for water managers.

Snow monitoring sites in the Western U.S. with at least 20 years of data. Additional sites with less data are not displayed.

The amount of aerosols in the air has direct effect on the amount of solar radiation hitting the Earth's surface. Aerosols may have significant local or regional impact on temperature. Water vapour is a greenhouse gas, but at the same time the upper white surface of clouds reflects solar radiation back into space.

Lake Powell was nearly full in the fall of 1999. A mere five years later, that high water mark painted white on the red rocks was about 140 feet lower. For five consecutive years, drought in the Upper Colorado River Basin limited the water flow into Lake Powell to be no more than 62 percent of the historical average. In 2004, the mammoth reservoir was only one-third full.

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 during the spring, summer, and fall, or to enjoy snow sports in the higher elevations.

Mountain snow plays a critical role in the hydrological cycle for most western states, stockpiling water during the winter and releasing it to the streams in the spring and early summer, which helps meet increasing demands for water.

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.