Scientists have estimated that dust in our atmosphere has doubled in the last century. Some airborne dust comes from naturally occurring geological events, such as drought or volcanoes.
But in some cases, humans have helped geology along, as when the Owens River became a water supply for Los Angeles early in the twentieth century. After this diversion, Owens Lake remained dry for years, and it was a major source of atmospheric dust in the U.S.
Other lakes throughout the world are becoming seasonally dry because of climate-induced droughts or because they have been tapped for irrigation water.
Why should we care about this? First, dust is a human health hazard. Even when it is composed of inert elements, dust can cause respiratory problems.
There is also evidence that atmospheric dust affects our climate. We know that the earth can be cooler in years following major volcanic eruptions, so we might think of dust as mitigating global warming. But dust can also interfere with natural cycles of clouds and precipitation, creating a feedback loop in which droughts occur more frequently and generate even more dust through desertification.
The U.S. EPA mandates dust control on construction sites and in facilities that generate dust. The easiest way to control dust is with water.
In fact that’s what’s happening now in California’s Owens Dry Lake: the agency controlling the Los Angeles water supply has restored a small amount of water to the lake, making the atmosphere less dusty and more breathable for nearby residents.
Web Links
Dust Levels in Earth’s Atmosphere Contribute to Climate Change
http://www.enn.com/sci-tech/article/42210
Photo, taken on April 19, 2012, courtesy of the U.S. Navy via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY, with partial support from the Field Day Foundation.