Dusty House? Blame Your Ancestors

Droughts are one cause of dustiness. But humans may also play a part in the development of increased dusty conditions. According to a new study from the University of Colorado at Boulder, dust in the western United States is up by 500% in the last 2 centuries. The reason? Human expansion into the west.

The study looked at sediments from dust blown into alpine lakes in southwest Colorado's San Juan Mountains. The sediments indicate a sharp rise in dust deposits coinciding with increased railroad traffic along with increased ranching and livestock activity, said geological sciences Assistant Professor Jason Neff, lead author on the study. Neff also indicated that while droughts can trigger erosion and increased dust deposition, western U.S. droughts during the past two centuries have been relatively mild compared to droughts over the past 2,000 years. This dustiness coincides with intensive land use and grazing.

An estimated 40 million head of livestock at the turn of the century caused massive changes in the ecosystems. The 1934 Taylor Grazing Act that imposed restrictions on western grazing lands coincided with a decrease in accumulation rates of the San Juan lake sediments in the study -- a decrease that continues to today.

While this study does not indicate drought conditions, the dustiness is similar to what happens during intensive drought-like conditions. A story I did in April of 2007 also pointed a finger to Arizona as a possible location for another Dust Bowl type of drought. The reason? Climate change was fingered as the culprit in a report from Nature magazine.

And finally, in case the causes of the Dust Bowl in the 1930s are unfamiliar to you, there is more information available now that technology has advanced. The reason? Ocean temperature changes and the jet stream may have been partly responsible.

Credits: EurekAlert!, a service of AAAS and the University of Colorado at Boulder.