Stirring Up Dust in the Desert
Billions of tons of dust blow off of arid lands every year -- and blow around the world. These dust storms make people sick, they kill coral reefs and they melt mountain snow packs.
In the Southwestern United States, dust storms are largely the result of tires and hooves, which are destroying natural biological barriers that once kept dust on the ground. But there are people studying, and trying to protect, the layer that can protect the planet from dust storms.
Jayne Belnap is one of those people. She's an ecologist, and you might call her Doctor Dust. She works for the U.S. Geological Survey in Moab, Utah. Recently, she gave Colorado dust researcher Thomas Painter a tour of the red-rock desert she calls home.
They meet in a parking lot off Interstate 70. Painter rolls down the window.
"Did we hit this day right, or what?" he proclaims.
"Yeah, this is a perfect day, except it rained, " Belnap says. "Which is why the soil is only sort of dusty."
She then whips out a photo of the local highway during a real dust storm.
"You really can't see anything. And the only thing they did was put 'Warning: dust storm' signs on the highway," Belnap says. "What exactly does that mean? What am I supposed to do when I hit this wall of black, knowing full well that if you slow down you're going to get rear-ended, and if you speed up, you're going to die!"
Belnap is a natural optimist facing a pretty grim situation. She says blowing dust actually leads to deaths on the local highway -- and it creates havoc around the world.
"That havoc can cause the death of coral reefs in the Caribbean. That havoc can be people in Beijing dying of respiratory diseases," Belnap says. "There’s a lot of things in dust that are not great things to have floating around in the air."
And dust also settles on the snow. In fact, that's what Painter studies, and what has drawn him out of the Rockies to meet Belnap.
"This year we had a major dust deposition event across Colorado and into Wyoming, that created snow melt at a time that snow melt doesn't occur," Painter explains.
Dust makes the snow melt faster, and that affects how fast the water pours out of the mountains and feeds the rivers and reservoirs of the West. Belnap says dust is the desert's little gift to the mountains.
"Isn't it nice of us to share?" she jokes.
Belnap takes Painter down the road to look at the geological formation known as Manco shale. It was a sea bed in the time of the dinosaurs. It's loaded with naturally occurring mercury and arsenic, and other nasties that blow when the wind picks it up.
Heading toward Moab, a one-time uranium mining center that is now a tourist town, there's a lot of dust in the air.
"We just had a jeep safari this weekend, which is when 10,000 jeeps show up here, and ATVs, and they run all over the place," Belnap said. "When we have activities like that, and it doesn't rain for a while, we get huge dust production off the area."
Jeeps are still streaming out of town as Belnap drives down the road. When they're off road, Jeeps break up a living barrier in the soil, a biological crust, that normally keeps dust from blowing. Cattle break up that crust, too. So do deer, which are much more abundant these days because cattlemen have made water available everywhere. And a prolonged drought in the area has made a bad problem even worse.
Belnap pulls off the highway and drives to a place that's a natural experiment in restoring these lands. It's a buffer zone around an airport, so it's been fenced off from cattle and jeeps for the past 20 years.
"This area is actually pretty stable," Belnap said. "You can see the physical crust on the surface. It looks like a mudflat, but it's not blowing away."
But the surface is still missing something important. It was disturbed many decades ago, but before then, it was crusted with lichens and mosses and held together by a kind of soil bacteria called cyanobacteria. Belnap has a nickname for these life forms.
"Let's go see crusties. They're the cutest things ever," Belnap says.
It's not as dramatic as the natural arches nearby, but the red and green striped rock is still a classic scene of the American West. This rocky hillside has somehow managed to escape the onslaught of cattle and jeeps.
Taking care not to disturb the soil, Belnap scrambles up the rocks and picks up a sample.
"So here's a nicely developed soil crust. All those different colors are different lichens," Belnap says. "We have mosses in here as well, we have cyanobacteria in here as well, and this is absolutely stable from both wind and water erosion."
The cyanobacteria themselves are microscopic, but they create strong threads. Belnap holds up a clump of dirt. Another clump dangles from a tiny thread. These threads do an amazing job of holding the soil together, she says.
The cyanobacteria grow quickly, but the mosses and lichens do not. Belnap says it has taken hundreds of years for them to grow here. And in the Mojave Desert, it took more like a thousand years.
That has huge implications for what Belnap really cares about: restoring the biological crust on these disturbed lands. She wants to stop the blowing dust.
"I hate giving up all my friends, and I'm giving up a lot of them by saying this, but if we're going to use these lands, we're going to have to find some happy medium," Belnap said.
That happy medium would be to let the fast-growing cyanobacteria return to the soil and spread their threads to hold it in place, but not to expect the return of mosses and lichens. Even reaching that happy medium could be difficult.
The situation in the West has gotten much worse in the past five years, since drought set in. And climatologists say there are signs this is just the start of a 30-year pattern known as a megadrought. The research on crusties was based on their life during wetter years.
"We don't have any idea of how what we now know applies to the future, if it's going to be a lot drier," Belnap says.
But, she adds, if we are going to do something about dust, the biological crust here really does need a break from hooves and tires.
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