UNM study reveals Southwest deserts produce more dust in warm periods, bucking global trends

A new study led by The University of New Mexico researchers has uncovered a surprising pattern in how deserts of the southwestern United States produce dust over long climate cycles. Unlike most of the world-where dust emissions peak during cold, glacial periods-the region's deserts become dustier during warm, interglacial climates, according to findings published in Nature Communications.

The research was led by Spencer Staley, a former UNM Ph.D. student and now assistant research professor at the Desert Research Institute, with co-authors UNM Professor Peter Fawcett, R. Scott Anderson (Northern Arizona University), and Matthew Kirby (California State University, Fullerton).

Globally, ice ages tend to be associated with sweeping, dusty landscapes. But in the deserts of Arizona, California, and Nevada, Staley and his colleagues found the opposite pattern. By analyzing a 230,000-year record of dust preserved in sediments at Stoneman Lake, Arizona, the team discovered dust emissions surged during warm, dry interglacial periods-times when global dust typically declines.

"Deserts in southwestern North America respond very differently to longer-term climate changes compared to other major global dust sources," Staley said. "Even though this region produces less dust than Northern Africa, the Middle East, and Central Asia, it is important to know how this region fits into the global picture. Our ability to predict and prepare for downwind impacts depends on it."

The study is the first to continuously trace dust blown out of southwestern North America across multiple glacial-interglacial cycles.

Although dust is often viewed as a sign of increasing aridity, the team's findings show the story is more complex. Dust emissions in the Southwest spike right after major wet-to-dry climate transitions, when ecosystems and landscapes are shifting rapidly.

"Once we realized what an incredible record of atmospheric dust deposition the Stoneman Lake core was, I expected that this record would look a lot like dust records in other parts of the world especially those from ocean sediments and polar ice cores. But the answer turned out to be much more interesting than that," explained Fawcett.

As the climate warms and dries, natural disturbances such as vegetation shifts, more frequent wildfires, and intense rainfall events can erode previously stable hillslope soils. Those sediments then wash downslope and accumulate in dust-prone environments such as alluvial fans, playa lakebeds, and river floodplains.

"In the long term, it doesn't matter how dry it gets if there isn't any fine sediment left to blow away," explained Staley. "While aridity certainly plays a role in dust emissions, the more fundamental connection is to landscape disturbance."

The team's insights come from an unusual source: a sediment core drilled from Stoneman Lake, a small sinkhole lake on the southwestern edge of the Colorado Plateau. Formed roughly 1.3 million years ago, the lake has quietly accumulated fine material, including dust blowing in from hundreds of miles upwind, for hundreds of thousands of years.

Stoneman Lake is one of the few places in the region capable of preserving an unbroken record of sediment deposition across multiple climate cycles. Using laser particle size analysis and end-member modeling, the researchers identified distinct populations of airborne dust within the lake sediments and reconstructed how dust fluxes changed over time.

"We were able to obtain a deep sediment core from Stoneman Lake because of the prolonged drought in the Southwest in the 2010's," said Fawcett. "It would have been impossible to drill down 80 meters from a small boat, but with the lake drying out completely, we were able to drive a drill rig out to the middle of the basin."

"Stoneman Lake is really quite special. Contributions of locally eroded sediment to the lake are quite small and distinct from dust, allowing us more easily quantify airborne inputs," said Staley.

The study highlights how sediment moves through interconnected desert landscapes. Hillslopes generate fine-grained material through weathering and dust accumulation. Floodplains, rivers, playas, and alluvial fans then store and emit this sediment into the atmosphere, sometimes for thousands of years.

Dust, in turn, influences cloud formation, atmospheric reflectivity, and nutrient delivery to ecosystems. Understanding how dust loads have changed in the past helps researchers improve climate models for the future.

Today, human activities including agriculture, off-road vehicle use, construction, and land-clearing play an outsized role in disturbing sediment supplies. Combined with ongoing climate change, the researchers warn that modern landscapes may be pushed into even greater states of instability.

"We found that increased dust emissions can persist for thousands of years when the landscape is disturbed," Staley said. "With continued warming and drying, we risk displacing the vegetation that protects remaining stores of hillslope sediment from erosion-potentially increasing dust loads across the region."

The full study, "Higher interglacial dust fluxes relative to glacial periods in southwestern North American deserts," is available in Nature Communications.

Staley and Fawcett conclude by stating that this research is relevant right here in New Mexico, explaining that the research discovered can have a similar relationship between dust, vegetation and climate.

"The findings at Stoneman Lake has renewed our interest in studying another long lake sediment record from the Valles Caldera in northern New Mexico that goes back further in time than the Stoneman Lake study," said Fawcett.

A current undergraduate student in the EPS department, Elias Draven, is working with Fawcett on a similar grain size study across glacial-interglacial climates to see if the opposite dust pattern holds here as well.

"Dust-prone features like those contributing to our record are found all across New Mexico. Therefore, we can expect similar relationships between dust emissions and landscape change here. Even so, our team is undertaking further research to study the behavior of dust sources across the state," concluded Staley.