Desert dust deposition reduces snow cover in Colorado Mountains



Dust deposition on the mountains of southwest Colorado may have reduced springtime snow cover by 1–2 months per year compared to low-dust conditions, a new study finds. When dust is deposited on snow surface, it increases absorption of solar radiation, accelerating snowmelt. Increasing land disturbances, beginning since the early settlers arrived in the western United States during the mid-1800s, have kicked large quantities of dust into the atmosphere; this dust gets deposited on the snow-covered mountains of Colorado. Skiles et al. used 6 years of observations, between 2005 and 2010, to understand how soil dust loading has affected snow cover on the San Juan Mountains of southwest Colorado during the springtime snow-melting season. The authors found that dust loading, which varied by an order of magnitude over the study period, was not necessarily related to the number of seasonal dust events. The increased dust load reduced snow cover by 25–51 days during spring, with the magnitude of impact being directly related to the amount of dust loading. The authors further suggest that the thinning of snow cover due to dust is greater than that expected from the projected 2°C–4°C increase in regional temperature.