Dust Storms Accelerate Snowmelt and Alter Ecology of Colorado Alpine Meadows
June 29, 2009

In a recently released study of snow samples and alpine ecology, researchers sought to determine how dust deposition affects snowmelt and how the timing of snowmelt affects mountain plants.  The study is reported in the Proceedings of the National Academy of Sciences, available online.  Heidi Steltzer of Colorado State University, Tom Painter of the University of Utah, and Chris Landry of the Center for Snow and Avalanche Studies are among the researchers who have concluded that dust storms arriving in the Colorado mountains from the Colorado Plateau, Arizona, Utah, the Mojave desert, the Sahara, and Mongolia are accelerating snowmelt and leading to the synchronized growth of alpine plants.  The study has two important implications for the water resource:

Water Quantity.  According to the study, dust levels increase as mining, livestock grazing, and other human activities disrupt the natural barriers that keep soil in place.  Current mountain dust levels are roughly five times greater than they were prior to the mid-19th century, due to increased soil disruption.  Increased soil disruption causes greater amounts of dust to disperse and deposit elsewhere.  Dust deposition in Colorado contributes to accelerated snowmelt, since dust absorbs heat that pristine snow would otherwise reflect.  In turn, accelerated snowmelt may alter the timing of water flows, causing overflow in the early summer season and lower water levels in late summer.  The delivery of water to urban and agricultural areas will, thus, be impacted by dust deposition in the Colorado mountain areas.  This year, twelve dust storms resulted in a quicker retreat of snow cover by more than a month.  Researchers note that greater use of semi-arid lands brings about more dust, which leads to more dust on the snow, more absorbed sunlight, and more enhanced snowmelt. 

Water Quality.  The timing of snowmelt indicates to mountain plants when to begin growing and flowering.  Typically, snow melts when the average temperature rises above freezing.  However, dust deposition causes snowmelt to occur at lower average temperatures.  When accelerated snowmelt occurs, plants wait until air temperatures have warmed consistently above freezing.  Once temperatures warm, these delayed plants burst forth all at once.  Researchers do not fully understand the consequences of this synchronization but predict that synchronized plant growth will lead to competition for water and nutrient resources and loss of less competitive species.  Additionally, delayed plant growth may increase nutrient losses which, in turn, decrease water quality. 

The study is available at the Natural Resource Ecology Laboratory, Colorado State University website. Click hereto read more.