'So I'm going to tell you about dust and how we're all doomed," began Jayne Belnap, a research ecologist with the U.S. Geological Survey.
She was among dozens of researchers gathered Tuesday at Northern Arizona University to present their findings on climate change on the Colorado Plateau.
Think back, Belnap said, to those massive sandstorms that sometimes make headlines in Beijing and Phoenix -- a photo of a wall of sand engulfing a city -- and you have some idea of what the future might hold.
At the crossroads of growing population in the desert, increased water demand, drought and temperatures expected to increase by 11 degrees by the end of the century, Belnap sees compounding problems for the Colorado Plateau.
"For this localized region, we're probably looking at serious drought ahead," she said.
But drought and any activity that disturbs typically unvisited areas -- from off-road driving to ranching or hiking -- kill the living agents that bind desert soil together, Belnap said.
A number of cities are currently tapping shallower aquifers, threatening to dry up more vegetation, she said.
As vegetation recedes, bare desert land reflects more sunlight and heat, burning away clouds that would otherwise hold in moisture.
"There's this huge negative feedback cycle in terms of precipitation," Belnap said.
Soil on the Colorado Plateau is eroding 10 to 1,000 times faster than it's being created.
The once-fertile dirt gets blown around, creating lung problems for humans. It also blows onto mountain ranges like the San Juans, creating darker-colored snowcaps that melt, on average, a month earlier in the year than usual due to increased sunlight absorption.
And that, Belnap said cities will get an early water supply but meager inflow when it's often needed the most.
"We've got a lot of dirty snow out there," Belnap said.
The desert isn't inherently dusty -- or it wasn't in the past.
In fact, it was 6.5 times less dusty before cattle ranching began in the 1850s, Belnap said.
Belnap called for more land use planning and education, and a little help from the audience of researchers.
"The moral of the story is, we need like 8 billion dust traps," she joked. "So could you all go buy some and put them out there?"
CARBON DIOXIDE AND FORESTS
Some researchers at the conference predicted grasslands and aspen stands will expand, taking over areas now thickly inhabited by gambel oaks, spruce, firs, mixed conifers, and pinyons.
Others suggested the various models forecasting less rainfall will lead to less vegetation overall, eventually feeding less-destructive forest wildfires.
And yet others expect forests across the western United States will expand as a result of climate change.
One of the unknowns mentioned by several researchers: How will increasing carbon dioxide levels impact plant life?
One group works this question from the opposite end.
Since the Horseshoe and Hochderffer fires burned 25,050 acres northwest of the San Francisco Peaks in 1996, the Horseshoe burn area has been releasing carbon dioxide, said Tom Kolb, forest ecophysiology professor at NAU.
"I think it's going to go on for decades," he said.
And this raises other questions about how the forests will still act as a sink to absorb global warming gases amid increasing prescribed burning and catastrophic wildfires.
Kolb and a team of researchers monitor carbon dioxide and water vapors from three towers above forest canopies in the Coconino National Forest.
The forest's ability to absorb carbon dioxide, Kolb said, is mostly determined by its total leaf area -- a link that could add a whole new dimension to considerations like prescribed burning and forest thinning.
THE DISAPPEARING PINYON
"We're seeing an overall drying out on the Colorado Plateau," said Gregg Garfin, of a research center at the University of Arizona.
Average annual precipitation could decrease by 5 percent to 10 percent by 2050, Garfin said.
But researchers also said climate models showed a lot of variability, with some showing the monsoon system over Arizona strengthening by 2090. If precipitation does decline, it appears likely to happen in May and June, Garfin said -- at the time of year where the southern end of the Colorado Plateau already receives very little moisture and plants are stressed.
Trees along the trail up Humphreys Peak are dying, said researcher Kirsten Ironside, of NAU.
A number of researchers presented data that the pinyons typically found alongside junipers around Flagstaff have already succumbed to drought, including north of the San Francisco Peaks.
"In northern Arizona, probably the most significant impact is on pinyon pine," she said.Arizona Daily Sun
