Dust to dust


That early spring afternoon looked like the opening shot for a bad doomsday flick. The sky west of Paonia, Colorado, brooded yellow at first, fading to sepia around its edges. Then, as the wind rose, it gusted to a hard orange-red. The mountain skyline to the southeast — just that morning, a white and blue sweep of snowy conifers and rocky cliffs — became a flat sawblade of silhouette.

It wasn’t the end of the world, as ominous as it appeared, this unexpected blizzard of billowing dust. It’s the kind of thing that happens sometimes on the edges of vast deserts, not a harbinger of global catastrophe — more Lawrence of Arabia than The Day After Tomorrow. Right?

Well, yes and no. That dust storm was one of several that blew into the Rockies in the spring of 2009, coating the mountain snowpack with pink grime. Over the last decade, scientists have recorded a marked uptick in these “dust-on-snow” events, as human incursions like cattle grazing and development break up vast swaths of soil crust on the Colorado Plateau, leaving little to anchor its powdery earth against the howling winds.

The dirt those winds heave into the Rockies makes the snowpack melt faster, spelling trouble for both ecosystems and human communities who rely on the mountains as a time-release reservoir. Meanwhile, on the eastern side of the Continental Divide, the wind has sent giant walls of earth rolling across the High Plains from drought-fallowed farm fields, evoking the infamous “dusters” of the Great Depression. Haboobs, as these great dust storms are sometimes called, are on the rise in the desert Southwest as well, closing airports, swallowing freeways and spitting out lethal multicar collisions around cities like Phoenix.

Events like these highlight how easily local impacts can build up to dramatic regional effects. But as writer Douglas Fox explores in this issue’s cover story, scientists are just beginning to understand that dust kicked into the atmosphere by manmade and natural forces has global impacts, too. In particular, this “vast network of airborne dust commerce,” as Fox describes it, has a profound influence on whether clouds form rain and snow, and where and when they release their bounty of moisture.

As climate change begins to shift wind patterns, and pollution adds new particulates and chemicals to the sinuous air currents that flow like rivers above Earth’s surface, linking continent to continent, dust source to dust sink, that network is beginning to reconfigure in ways that may in turn remake the environments — and economies — of the American West. If we’re lucky, the West of the future will be kind to the civilization we’ve built and to the natural places we love. But if California’s current extreme drought is any indication, the changes in store may be of the more apocalyptic variety.

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